spray foam 10x the cost, why do it.
love the idea of the spray foam but I wonder if my money isn’t better spent elsewhere. 2 1/2 inches would be about R-17.5, 3 1/2 inch fiberglass is R-13. 600 sq ft of spray is around 1000 dollars, same area with fiberglass is 150 bucks. I’d still have to put plastic on fiberglass to get vapor barrier but significant difference for 4.5 more insulating value. I could double the fiberglass, 7 inches thick and have R-26. This is for floor over crawl space. Obviously the fiberglass is my cost, no labor as DIY project.
Kevin
Replies
I am looking at the exact same decision as you. I decided on Icynene spray foam for a few reasons.
1. Air movement through fiberglass significantly diminishes your R value leading to air infiltration into your house (through fiberglass). Ultimately this results in a higher heating cost.
2. As gas prices continue to increase the additional investment will be paid off sooner.
3. Fiberglass is a PITA to install.
I would look into an open cell foam (Icynene) as the cost is significantly less than closed cell. Your R-Value is not as great on paper but once again you eliminated air infiltration. As far as I know, an additional vapor barrier is not needed.
To save costs I am going to have my walls foamed (About double the installed fiberglass cost) and blow the attic with cellulose myself.
I'm in a very humid location, so the closed cell appealed to me because of it's vapor barrier. I'm wondering if, since I've lifted the house and added 20 yards of sand under it (about 2 feets higher than it used to be), will moisture be as much of a problem as in the past. There is blown in fiberglass insulation in the walls, this has settled and I'll be replacing it once the interior beadboard comes down. At this point in the project I'd rather spend the money on other things, like a masonry fireplace, copper roof, etc. The crawl space insulation can be done later if I do go with spray foam.
There are lots of variables that affect the actual insulating value ... and insulation isn't the only thing you ask of the material!
Fiberglass is cheap, versatile, easy to install .... and a whole revolutionary advance over earlier attempts using sawdust, etc. Yet, it loses a lot of its' value over time, when it gets wet or disturbed, and details of vapor sealing are critical. It's also nesting heaven for critters.
Foam has a way of getting into every nook and cranny, and is pretty much waterproof once cured. It does a great job of blocking air infiltration, soundproofing, and can make a wall noticeably stiffer. Its' one big drawback is that it burns like rocket fuel - and you really need to keep that from happening.
Another, less often mentioned, drawback to foam is that it is nearly impossible to change the wall later on. You can forget adding a receptacle or phone line that you forgot.
Given the funds, I'd choose foam every time ... even with the drawbacks. Fiberglass seems to be squarely in the domain of those who are doing a job for someone else, and doing it as cheaply as possible!
"Its' one big drawback is that it burns like rocket fuel - and you really need to keep that from happening." Are you saying it's a danger while it's still liquid or is this a concern forever once the stuff has dried?"Another, less often mentioned, drawback to foam is that it is nearly impossible to change the wall later on. You can forget adding a receptacle or phone line that you forgot." My floors are on 6" joists, the guy was saying 2 1/2 inches for floor and roof, so this still leaves plenty of room for retrofitting. The walls are 4 inches and he said 2 inches there, again room for wires, etc.
The cured foam does present a very real fire hazard; that's why the manufacturers ALL want the stuff place behind drywall, or a similar fire protective layer. There's no getting around this; foams have been described as 'solid gasoline' more than once by those who test them.
so how do you cover it with a firebreak if it's the underside of a floor in a crawlspace? or is it not required in that situation.
A horizontal application, such as under a floor or ceiling, is the absolute worst place for foam, as far as a fire is concerned. Here, in particular, you simply MUST close it in with drywall on the underside. I'm not so worried about the top face. Why? Because, at the slightest exposure to heat, the foam will fall free, drop to the floor, and burn there with great vigor. While one might argue that a crawl space is but dirt and gravel, with no source for a fire ... I ask that you reconsider.
Many crawl spaces have quite a bit of construction trash in them. There are almost always numerous wires, etc, passing through. Animals have been known to chew on such things.
Over time, various trades tend to leave even more junk down there. Often there is a furnace or water heater present. Repair work may, itself, provide a start to a fire. Far fetched? It was exactly such maintenance operations that started a fire that nearly destroyed the Browns' Ferry nuclear plant back in the 70's. A plumber, checking for leaks with a candle, ignited some spray foam. It's that easy to do. Likewise, I just finished the replacement of a historic community center that was leveled by the fire that started when the plumber repaired a leak in the crawl space. (I don't mean to single out the plumbers here - it's just two examples I have handy.) To be fair, there was no foam present; the old, dry wood was flammable enough by itself!
You are likely correct in your concerns about Doc's possible foam insulation in the floor. The b!tch of it is, that's a perfect place for foam and a terrible place for FG. With a plank subfloor and plank wood flooring over it, you have a major source of air infiltration. A typical FG install under a floor like that will be worthless, while a foam install will actually work.
Hey Dave,More confused than ever, I'll probably start by asking the building department what's required with different materials, does spray foam have to be covered, etc. I did see an underlayment at HD which would go over the 4x8 plywood subfloor, under hardwood flooring that is supposed to be a vapor barrier. Kevin
http://forums.taunton.com/tp-breaktime/messages?msg=95315.7 wonder if this would work in my situation, the second part about the rigid foam.
You would have to find out if the inspector will allow foam of any kind. Rigid with a foil face may be OK, depends on the brand and the inspector. You should go in and talk to him, see what he says.
That's what I was saying. All this discussion may be a waste of time if BI won't allow it. What did you do under your house? If I rmember correctly, you were waterfront, or very close at least.
Some polyio is rated for exposure in non-habital areas. Attics and crawlspaces..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Foam is fire rated...that is to say it will not sustain fire once the flame is removed.
We've been over this topic many, many times. I care not what claims the manufacturer may make, nor what test results one may get from simply holding a match to a small piece .... the fact is, EVERY foam available burns quite vigorously when tested under realistic, industry standard fire tests. Period.
That's why foam simply MUST be protected by drywall, or a similar protective material. IMO ... and it's only an opinion, since there is simply no way to objectively measure my perceptions .... all the various 'fire resisting' additives do is make the smoke generated even nastier than it already is. Foam burns - and with great vigor. It gives of about double the heat of an equal amount of wood, and more smoke than a burning tire. You can either chose to ignore these facts ... or follow the manufacturers' instructions -that's right, the same folks who so carefully word their 'fire retardant' claims- and place it behind a barrier. The recent hotel fire in Las Vegas is a case in point. All that burned was the stucco covered foam trim at the top of the building. Yet, that hotel is STILL closed. Viewing the video will show just how nicely even 'treated' foam can burn.
Well this foam wont burn:http://bauerspecialty.com/insulation/air-krete/
Thank you for the link. I had seen a similar material used, in block form, overseas. I was not aware that it was available here, nor that it was installed 'on site.'
I've got an unfinished attic/upstairs area that is in need of insulation in order to finish it off. I'd love to spray foam the entire rafter cavity but cost, as you well know, is high.
I'm going to have 1" sprayed to seal it and then strap the rafters(this needs done because they are all over the map in, or should I say out of plane) and do like Mike Smith shows on his houses, use a mesh over the strapping and spray cellulose in the cavity.
The foam guy that I will use charges $1 per sq so I'll have $1500 just in the foam! Dont know what the celoulose will cost?
Doug
so your more interested in the vapor barrier aspect, I'm guessing your not venting the attic and the foam allows this. The cellulose wouldn't work for me, with the moisture on the island, it would be like I was trying to have a mold farm.
so your more interested in the vapor barrier aspect, I'm guessing your not venting the attic
Right, also a combination vapor barrier and sealing a 150 year old roof, something I dont think I can accomplish with just the cellulose.
How is it that Mike Smith can get away with using the cellulose, he's in RI, thats close to the water?
I dont know how it works near the ocean so its totally greek to me.
Doug
not sure of Mikes situation, I saw the thread you spoke of and thought if I did do it his way I'd use blown in fiberglass instead of cellulose. My house is on an island,a big sand bank really, with the water table about 2 feet below grade, If I were on an island made of rock it might be different.
fiberglass will not absorb, then release moisture
cellulose will
the two types of insualtion are not interchangeableMike Smith Rhode Island : Design / Build / Repair / Restore
i live and build on two islands
"Adverse Conditions" is on Green End Pond, 3/4 mile from 1st Beach in Newport
"RFH Ranch" is on Jamestown.... both are not waterfront... but both are definitely ocean atmosphere
"Quarterdeck" is waterfront
cellulose is the MOST forgiving , in terms of handling moisture, of the three types of insulation being discussedMike Smith Rhode Island : Design / Build / Repair / Restore
aren't you afraid of the potential mold problem with cellulose? I mean, it's what mold eats right? The point of paperless drywall and all that.http://www.ncbi.nlm.nih.gov/pubmed/16499151when I googled it there were just as many saying it did NOT contribute to mold, just to be fair.
Edited 2/23/2008 9:43 pm ET by dockelly
no... cellulose is treated with borates
cellulose can absorb moisture, then release it
the cellulose is not a condensing surface
fiberglass ( the fibers ) is a condensing surface......moisture will go thru until it reaches the dew point, then it will condense , coagulate, form drops... collect and soak other materials to feed mold
for cellulose to do that you need a source of liquid water... a plumbing leak, high water, roof leak, etc
in other words the source of the mold is not the cellulose, it's the water leakMike Smith Rhode Island : Design / Build / Repair / Restore
I get that it's treated, but won't that treatment leach out over time. Not sure you know the answer, just trying to educate myself before I commit one way or another. BTW, I was on Jamestown when Hurricane BOB hit, watched this professional sailor whose boat was named Duracell pull anchor and try to sail into open sea. The waves actually drove him into shore, but the way he was ducking and weaving to avoid the other boats was amazing.
yes..... he was lost at sea about a year later... if i remember... Duracell dropped her keel, capsized and sank
Mike Plant drowned...his girlfriend claimed his estate
here's a lead up to the race
http://query.nytimes.com/gst/fullpage.html?res=9C0CE3DA153FF933A0575BC0A966958260
and here's the results
http://www.sevenoceans.com/SoloAroundTheWorld/ShipMail/Plant.htm
....borates won't leach out
heres the deal.... fiberglass sucks
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/23/2008 11:12 pm ET by MikeSmith
yeah, knew he died. heard they never found his boat. I'm going to have to rethink this whole insulation thing. I have two young kids and really don't want them to get sick because of the wrong choice. signing off, no need for a reply.Thanks
Kevin
OK I Lied, didn't see your second link, so they did find the boat.
Mike
While we have many disagrements I am in complete agreement with that statement.. Fiberglas sux's as an insulator..
the cellulose is not a condensing surface
Why is that? Something to do with the surface?
I've had a lot of fun with rodents and snakes in the fiberglass in my shop.
PAHS Designer/Builder- Bury it!
the cellulose will simply absorb moisture until it reaches it's saturation point
firberglass cannot absorb any moisture, but the fibers are great condensing surfaces
ever notice how a wall will have various surfaces on it..... maybe some is bare wood, some is painted, perhaps there are some metal sheets affixed to it
in the right temperature and humidity levels, water will condense on the paint, or the metal sheets, but not on the bare wood
the bare wood is absorbing the moisture, the paint and metal are acting as condensing surfaces
same thing can be observed in an attic, given high humidity and low temperatures,
the moisture will condense on the roofing nails protruding thru the plywood, but the plywood will appear dry
so the bare wood is a good absorber, cellulose is an even better absorberMike Smith Rhode Island : Design / Build / Repair / Restore
Mike, thanks for the explanation.
I'm a little skewed here, no condensation except glass after a long hot shower. Which is what you were talking about.
The hickory mirror frame doesn't condense, the plastic laminate cabinets get slightly damp. Both about the same temp as the glass.
Not a small point you're making. Hope everybody else got it.
And with luck this time, this will post. %*#$#?! ISP.PAHS Designer/Builder- Bury it!
the bare wood is absorbing the moisture, the paint and metal are acting as condensing surfaces
Glass and metal are better conductors than wood or drywall.Even if all materials are at the same temperature....The better conductors will carry the heat energy away faster.There will be less heat available to evaporate condensation on the glass or metal.Condensation is happening all the time. It is the accumulation of condensation that we notice when evaporation can not keep up.
Here is a video that demostrates the dewpoint temperature:http://www.youtube.com/watch?v=ZBlTzkpMIoQHere is a video that speaks of the conductance:http://www.youtube.com/watch?v=HiX7DKUlAOM&feature=related
Edited 2/24/2008 7:37 pm by homedesign
home ... what i was trying to demonstrate is that the fibers in fiberglass insulation are great condensing surfaces
inside a wall
my illustration was to give someone a visual that they can relate toMike Smith Rhode Island : Design / Build / Repair / Restore
Mike,
I was just adding some references that I found recently that were sort of on topic. This is a very fascinating subject to me. Thanks for your thoughts.
John B
Mike,
I agree with most of your post, except your assertion that condensation occurs on fiberglass fibers. This is an old myth from the 1970s that William Rose and Anton TenWolde (among many other researchers) have been trying to correct.
From a review of Rose's book, Water in Buildings, in the July 2005 issue of Energy Design Update:
"When builders talk about “condensation” in walls, they usually imagine a process similar to the formation of sweat on the outside of a bottle of beer. In fact, such condensation almost never occurs in a wall; what actually happens is sorption. Rose writes, “Condensation — the phenomenological formation of water droplets — does not occur on the surfaces of porous and hygroscopic materials.” He elaborates, “The conversion of water from vapor to sorbed water is not condensation. Sorption is a better term, covering adsorption and absorption. Where the accumulation of water on a mirror or a highball glass occurs rarely and only at a discrete set of surface temperature and air humidity conditions, sorption (i.e., adsorption or absorption, meaning the takeup of water) occurs just about half the time. The other half of the time materials are desorbing, giving off moisture. … Nonsorptive materials may require a coaster; sorptive materials often are coasters.”
From a report on a speech by Anton TenWolde (Energy Design Update, December 2002):
"Many of you are familiar with a chart like this [shows a slide]: you project the temperature profile through the wall to calculate saturation vapor pressures ... Then you calculate vapor pressures based on the permeance of the materials, and you come up with a profile like this. I have seen hundreds of these profiles, and many seem to show condensation occurring in the insulation. This has encouraged a lot of research into the performance of wet insulation. But the picture is wrong, because the vapor pressure has to be below the saturation pressure. You need to make a correction, and if you do that, if you redraw it, the condensation does not occur in the insulation. We thought there would be a problem with condensation in the insulation, but all the action happens on the sheathing and the interior vapor barrier. We’ve confirmed this by opening up walls. The action is never in the insulation."
Edited 2/25/2008 8:52 am ET by MartinHolladay
martin.... the first paragraph is gobbledy gook... he's even inventing terms and talking about coasters
the second one is more interesting because he says he has opened walls and not found a problem
<<<<But the picture is wrong, because the vapor pressure has to be below the saturation pressure. You need to make a correction, and if you do that, if you redraw it, the condensation does not occur in the insulation. We thought there would be a problem with condensation in the insulation, but all the action happens on the sheathing and the interior vapor barrier. We’ve confirmed this by opening up walls. The action is never in the insulation.">>>>
but , consider this:
if i direct a stream of air at the correct speed ( not too fast, not too slow )
and i bisect that stream with a filament of fiberglass insulation
and the temperature is at the dew point , as is the filament, then the filament will become a condensing surface
now , perhaps he's saying that the same stream of air will then also act as an evaporative ..
but in the wall structure, the filament is not alone, it is crammed in with millions of other filaments
if there is air moving thru the wall, and the outside temperature is low
at some point on it's journey , the air stream will fall in temperature to it's dew point and condensation will commence, water droplets will coagulate and water will start to flow
if he opened the wall and found that the only surface acting as a condenser was theplywood sheathing, then i contend that the dew point temperature had simply not moved far enough into the insualtion
now, i'm not a heating engineer..... so take my theorizing for what it's worth
my lack of understanding probably has to do with this part :
<<<<the picture is wrong, because the vapor pressure has to be below the saturation pressure>>>
but hey, whadda i no ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/25/2008 9:04 am ET by MikeSmith
Mike,
William Rose is a building scientist and researcher at the University of Illinois in Champaign. Although he is not using the vocabulary familiar to most builders, I can assure you that it is not gobbledy-gook, and he is not making up words. Sorption is the accurate word to describe the process by which certain materials, like plywood sheathing, take on water.
Believe it or not, the paragraph quoting Rose basically backs you up, Mike -- confirms what you posted. TenWolde, however, disagrees with you concerning condensation on fiberglass fibers. As I understand it, the gist (in layman's terms) is that in a typical wood-framed wall insulated with fiberglass batts, conditions will not occur leading to condensation on or in the fiberglass. The condensing surfaces are elsewhere: in winter, the interior surface of the wall sheathing, and in summer, the exterior surface of the polyethylene (if there is poly).
Edited 2/25/2008 9:41 am ET by MartinHolladay
thanks martin... another day, another learning process
as to this
<<<<TenWolde, however, disagrees with you concerning condensation on fiberglass fibers. As I understand it, the gist (in layman's terms) is that in a typical wood-framed wall insulated with fiberglass batts, conditions will not occur leading to condensation on or in the fiberglass. The condensing surfaces are elsewhere: in winter, the interior surface of the wall sheathing, and in summer, the exterior surface of the polyethylene (if there is poly).>>>>>
i wonder if this is a case of the sheathing being a more efficient coagulating surface
as opposed to the filaments
and of course, if the air is not MOVING thru the fiberglass, then the only movement will be from vapor pressure
my understanding is that most of the movement takes place around things like electrical devices and plumbing penetrations
so the Air Tite Drywall defense will certainly make a difference
i still prefer my cellulose which effectively removes all condensing surfaces within the cavity
Mike Smith Rhode Island : Design / Build / Repair / Restore
Martin,
Thanks for jumping in here. I really think that William Rose knows what he is talking about. I am currently reading his book "Water in Buildings" and I am slowly,slowly starting to understand.
John B
Edited 2/25/2008 9:35 am by homedesign
"But the picture is wrong, because the vapor pressure has to be below the saturation pressure."
You're going to have to post something that makes more sense than this to convince me that condensation can't occur within a fiberlass batt.
Does he mean that there can't be condensation because the vapor pressure within the fiberglass can never reach saturation (100% RH or dew point)?
Is he trying to suggest that the relative impermeance of the wall materials won't allow sufficient water vapor into the insulation cavity to ever reach saturation?
This may be the case with diffused water vapor, but we know that most in-wall condensation occurs from moisture-laden air transport and we know that air moves freely through fiberglass batts.
There will be a temperature and humidity gradient though a fiberglass batt, and when the temperature of the moisture-laden air reaches the dew point, there will be condensation on any surface but "the surfaces of porous and hygroscopic materials".
The surface of a fiber of glass is no different than the surface of a pane of glass. They are both condensing (i.e. non-sorptive) surfaces.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I'd like to add a few thoughts to the argument as to whether or not moisture will/can condense on fiberglass fibers within a wall (heating situation). I think I have adjusted my reasoning over the last year. Previously I would have argued that condensation within the cavity ought to be easily predicted.I suppose we do have to distinguish between movement of moisture by convective air movement (ie. leaks of air into the wall cavity) vs. pure diffusion through the wall.First, consider a tight wall assembly where heat is moving purely by conduction and water vapor purely by diffusion. Assume that the sheetrock is painted so that the permeability of the inside wall is reasonably low. Further assume that the sheathing is typical plywood or OSB, both having fairly low permeability.Within the cavity, there will be a temperature gradient, getting progressively colder moving toward the outside, due to the R value of the FG insulation. If the cavity consisted of a three-layer sandwich of insulation-metal plate-insulation, then there would be essentially no temperature drop across the metal plate, due to its high conductivity.As far as water vapor movement within the FG insulation in the cavity goes, there ought to be almost no concentration gradient at all. This is due to the exceedingly high permeability of the FG insulation. The situation is much like the absence of temperature gradient in a metal plate within the insulation. No real resistance to flow of heat or diffusion of water vapor results in essentially no gradient in temperature or water vapor concentration. As the molecules of water diffuse through the sheetrock and into the cavity, they spread out much more rapidly through the very porous FG.If we start with a cavity that is fairly dry, and then begin to introduce water vapor into the cavity by slow diffusion through the sheetrock, the concentration in the cavity will increase, fairly uniform everywhere, until it reaches saturation at some point. That point will be the coldest surface, at the sheathing. Condensation and immediate absorption into the wood will occur.Offsetting the buildup of water vapor concentration within the cavity will be the ability of the sheathing to pass water on through to the outside world. As its water content increases, so does its permeability, or so I've read. If the permeability of the inside wall is sufficiently low, then of course the air within the cavity will never reach saturation anywhere.If saturation is reached at the sheathing, the removal of moisture by condensation/absorption will keep up easily with the rate of diffusion of water into the cavity from inside the house. Remember, in this case we're talking about a leak-sealed wall.The cold sheathing becomes a dehumidifier for the whole cavity, and the concentration of water vapor within the cavity should never increase to the point of condensation at any place warmer than the sheathing.Therefore, for the case of tight wall construction, we can't use the relative humidity within the house to determine where condensation may occur within the cavity or at the sheathing. The air within the cavity will simply be at a much lower absolute humidity than within the house.Now, lets take a stab at the second case, with a typical non-tight wall, and warm and more moist air leaking into the cavity. Besides introducing far more water vapor into the cavity than by simple diffusion through painted sheetrock, convective air flow also introduces heat faster than by simple conduction.One can argue that convective air flow will raise the temperature of whatever piece of FG insulation it passes through. Certainly the flow of air will disperse away from the point of entry. But any moisture introduced by leakage also will diffuse rapidly through the very porous batt.I supppose the severity and localization of air leakage will determine whether condensation will or can condense other than at the sheathing. At some level of intrusion, the rate of introduction of water vapor would overwhelm the ability of the wall structure to absorb it. Then there are major problems.It also can be argued that since air can't leak into a cavity unless air also is leaking back out somewhere, then the air within the house must necessarily be fairly dry unless deliberately humidified.Please let me know if my reasoning is sound for the case of the tight wall cavity. As far as the leaky wall goes, I guess it's a matter of degree. The closer it approaches tightness, the less likely condensation within the insulation should be. This should be a solid argument for the air tight drywall approach.
i don't see any flaws in your reasoning....
as remodelers , we're always taking walls apart, truth be told:
here's what i observe
most fiberglass insulation jobs are just terrible , it's the nature of the kraft paper and the installation techniques... almost like they are designed to be edge leakers
i also see lot's of evidence of vermin and rodents living in the insulation
most of the water damage i see is due to exterior leaks
and the balance are due to plumbing leaks
the fiberglass insualtion makes these leaks worse ( same would be true of cellulose, of course ), since it slows down the drying process if the insulation is saturated
many leaks in old houses with no insulation , have never resulted in rot, because the wood could dry before rot would commence, there would be water stains, but no rot
anyways, your 2d scenario ( large air movement with warm humid interior air ) i think would result in condensation within the cavity, and at times , faster that then ability of the sheathing to bleed it off
i have seen this phenomenom in attics where warm moist air is condensing on the roof sheathing and running down the rafters to the wall plate
and i have seen this in crawl spaces with super saturated floor framing
so.. bottom line.. the key appears to be control of moisture
and a lot of the installed fiberglass insulation is just really terrible, both in walls and in attics..... i mean really terrible
now , given a choice between the same average installer, installing cellulose or installing fiberglass
if nothing else was different ( absorption, vermin resistance, r-values )
the installed cellulose will be a better installation than the installed fiberglassMike Smith Rhode Island : Design / Build / Repair / Restore
the fiberglass insualtion makes these leaks worse ( same would be true of cellulose, of course ), since it slows down the drying process if the insulation is saturated
I don't believe the same would be true of cellulose unless it reached full saturation (about 20% of its weight in water). Because cellulose is highly hygroscopic (more so than solid wood) it tends to draw water away from wood framing and diffuse it through the cellulose, both protecting the wood from reaching saturation and allowing gradual diffusive release.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I think your reasoning is sound, with the possible exception of this statement:
"The air within the cavity will simply be at a much lower absolute humidity than within the house."
The permeability of dry CDX is 0.75 (a vapor barrier), though it will increase to 14-20 when fully saturated. The perm of drywall is 40 and latex paint is 3.5-6.
So, until the sheathing reaches full saturation, the inside skin could be five times as permeable as the outside, causing a rising RH within the cavity (and the FG insulation). At some level of saturation, the plywood would start to dehydrate the cavity, but there could very well be condensation within the insulation before that occurs.
I agree that this analysis is an argument for the Air-Tight Drywall Approach, and it's also used to justify sprayed foam since an air barrier on either side of the wall will stop air flow (as long as horizontal framing joints and vertical utility penetrations are also sealed). But it also seems to be used to justify spraying 1" of foam and filling the rest of the cavity with FG. This will not likely prevent the temperature gradient from causing a dew point within the FG/stud bay and it will make the outer skin impermeable to both water vapor and liquid water, trapping all diffused moisture within the cavity.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
"So, until the sheathing reaches full saturation, the inside skin could be five times as permeable as the outside, causing a rising RH within the cavity (and the FG insulation). At some level of saturation, the plywood would start to dehydrate the cavity, but there could very well be condensation within the insulation before that occurs."My point in the case of the tight wall assembly is that, given the relatively low permeability of painted drywall and the far greater permeability of a FG batt (mostly just air), as soon as water vapor passes through the drywall (slow rate) it will diffuse rapidly throughout the cavity. There just isn't much resistance to this diffusion within the batt. There ought to be almost no water concentration gradient within the cavity.What would you expect the perm value of a FG batt to be? It ought to be fairly close that of just dead air.The concentration within the cavity won't be able to rise to anything much greater than what is dictated at the temperature of the sheathing, the coldest spot. As I said, the sheathing will be the dehumidifier for the cavity.Now, with an open-cell foam, this might be different. OC foam has a perm value of 6-10 for a 3" thickness, so that is a substantial resistance to water diffusion. There would be a concentration gradient through that insulation. But then the perm of the whole wall would be so low that there ought not to be any problem. The absolute rates of water flow would be exceedingly low.
OK guys, what are your thoughts on this wall system we have been using recently. 2x6 wall w/ 2' oc. studs, exterior sheathing consisting of 7/16 osb structural sheathing covered with 3/4" foil faced polyiso sheathing. Interior side insulation is 4" min. spray foam open cell foam, drywall interior finish. My thinking with the exterior sheathing was to cover all stud and plate locations with a continuous layer of R-5 insulation as a thermal break and the open cell foam was a compromise in cost to a full closed cell foam system. From an energy usage view this is working extremely well. From my research and in talking to foam installers this seems to be relatively safe from moisture problems. I first used this on my own home about ten years ago, and when opened up for an addition, I saw no signs of any moisture.
You may not have moisture problems, but you don't have a well-insulated wall either.
If you're using 4" of Icynene (R-3.6/in), you might have an average wall-section R-value of 18.7.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Bish
Stick building while it has a long tradition is simply not as energy efficent as some other building methods..
It doesn't matter if the walls are 2x4's or 2x6's there is a thermal bridge at each stud..
ICF's and SIP's offer real alternatives to mention just a couple..
Look at yourself.. If you are a younger person capable of accepting new ideas and quickly adapting to them, you should embrace those technologies.. It's far better to be at the leading edge of something gaining wide acceptance than to be at the trailing edge of old tecnologies trying to hang on with a smaller and smaller market share.
Old dogs like myself who can't adapt or change aren't in for a smooth future..
Hi Frenchy,I don't know if you remember, but I asked you along time back to post some pictures of your timberframe. This led to a discussion on resizing and uploading pictures. Did you ever get to post pictures? If yes do you have a link, or even time frame when you posted so I can narrow down my search?Thanks
Kevin
dockelly
go to 85891.1 and 94041.1 plus 86920.13. there are a few pictures.
Stick building while it has a long tradition is simply not as energy efficent as some other building methods..
New technologies might offer improvements (though they almost always come with significant environmental liabilities as well), but there is at least a 30-year "tradition" of super-insulated wood frame buildings.
I've built a number of double stud wall houses and my modifed Larsen Truss framing system is among the most energy AND resource efficient building systems out there.
R-40+ walls and R-60+ ceilings with virutally no thermal bridging. Annual heat requirement in an 8,000 DD climate of less than a cord of wood per year.
HERS rating of 46. Effective system heat load of less than 1.5 BTU/SF-DD.
Show me any other buiding system which even comes close.
I'm not suggesting it's the best option for every application, but your statement is simply unsupportable.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Riversong,
There is effectively no real cost differance between a SIP with an R30 ratiing and one with an R50 rating. My R30 walls were just under $3.00 a sq.ft. and the R50 ceiling panels were just under $3.50 a sq.ft.
Since most energy lost with those extremly efficent walls is thru doors and wndows there is a point of deminishing returns.
In your case of stick building are you telling me there wasn't a thermal bridge between the roof deck and the ceiling of some sort?
Same with ICF's although the need for added concrete in the deeper form may be mute..
To gain real energy efficency you can easily supliment the foam and massively exceed any wall systems requirement. Right up to the point of deminishing returns..
I understand your concept of embedded energy which is why foam attracts me.
Yes it's an oil based product but it's extremely lite in weight and compact untill locally fabricated. Once fabricated it does become awkward untill in place but due to it's light weight it is something that can be handled with simple muscle power if that is a priority.
Frankly given the choice of using a few gallons of oil as an insulation media or using Fiberglas With all it's eviornmental costs I'll take foam..
Frankly given the choice of using a few gallons of oil as an insulation media or using Fiberglas With all it's eviornmental costs I'll take foam..
No disagreement there. Fiberglass should be outlawed. I tell my students that, if an engineer set out to design the worst insulation possible, it would be fiberglass.
In your case of stick building are you telling me there wasn't a thermal bridge between the roof deck and the ceiling of some sort?
Minimal. The sill and (sometimes) ceiling joists are the only framing bridges, but they bridge 12". The 1x4 or plywood gussets and the plywood window boxes also bridge from inside to out. But the overall percentage of bridging is less than any other wood frame system that I'm aware of. And I use no more wood for my 12" walls than what's used in a code-minimum 2x6 house.
The gussets degrade the overall wall section R-value by only 1.4%, and my entire wall assembly (including inside and outside sheathings) offers R-45.
Here is a link to my system:
http://www.builditsolar.com/Projects/SolarHomes/LarsenTruss/LarsenTruss.htm
To each his/her own, but I simply won't build someone a plastic box and call it a home. I call that the hermetic house (as in hermetically sealed). I teach that a house (our third skin), like our first skin and our second skin (clothing), must breathe in order to maintain a healthy and comfortable living space.
And a house should be made of materials that don't develop a static charge and attract the negative ions out of the interior space.
Also, bottom line for me in terms of sustainability (not just of houses but of our enture society) is that materials and methods should be as local as possible - not only to minimize embodied energy and other environmental costs, but to support a small-scale and local economy.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/26/2008 2:04 pm ET by Riversong
Riversong,
I hope you understand that I stand 4 square with you on the subject of sustainability.. which is why I'm such an advocate of ICF's and SIP's
Foam placed in a landfill can be expected to be there for thousands of years.. which is why I see a need for recyclable foam. SIP's should they ever need to be removed can be relatively simply recycled.. However that very durability of foam is what makes it such an excellant material to build with.. ICF's are more problematic but their durability is so much greater than the durability of stick built homes.
Fire is a near impossibility with ICF's not so with Stick built..
Insect damage and rot are also likely destroyers of stick built homes but would be virtually non-existant as a means to destroy a ICF home..
Finally wind.. Tornados are a real menance here in the midwest as are straight line winds.. ICF's are rated for 200 MPH wind speed. Reality is that little more is required to increase that to level 5 sustainablity.
Your attack on the nature of "Plastic" isn't worthy of you..
The plastic in foam is a hidden media we can't and don't interact with it, instead it is covered and protected many differant ways all of which adds to the comfort and enjoyability of the home..
Finally as for letting a house breathe.. absolutely! But in a controlled way.. A thermus is a good retainer of heat not because it can breathe but because it can be sealed up untill the heat used.. that should be the function of HRV's
Todays HRV's are really crude and poorly done.. 80% efficency is the best that can be achieved.. But the future is extremely bright.
The future will see improvements my mind can only dream about. recycling of moisture,, 99% heat recovery, time of day useage, capture of solar gain, etc..
So you're saying it would be fine to live in a thermos bottle as long as it had a good mechanical ventilation system?
I call that a house on CPR. Supports life as long as you keep pumping.
As far as future technologies, there's never been a technology invented which didn't have unintended consequences. But the simpler the technology, the less impact.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Riversong,
Well several points wrong with that annalogy. Todays HRV (which i've said how little I respect) all have fans/motors etc.
Absolutely no need for that.. Use basic physics instead. Hot air rises, cold air settles..
Time of day, sunlite conditions, etc. should determine when air exhanges are made.
Windows can and do still open so pleasant days that is your homes HRV system..
Thoughtful design and placement of overhangs and windows will allow breezes to flow thru the house even on rainy days..
My own home should be an example.
On days when the temp is as high as the low 90's there is no desire for me to turn on A/C it tends to be in the low 70's if there is a slight breeze..
Conversely Even though my neighbor shades me badly to the south I can have the house comfortable without furnace down into the 50's and even sometimes into the 40's comfortable as in near 70 degrees..
I suspect those principles meet your requirements for simplicity..
So how do you guarantee a minimum of 0.25 ACH in the winter?
Opening a window in the heating season isn't a HRV - it's a Heat Loss System.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Riversong
Right now that is what I have.. heat loss system.. same as a stick built house without a HRV.
However I will have a HRV if I have to design/build it myself once I seal this place up completely..
Todays temps in the 20's and my small undersized furnace hasn't run in several hours.. thermostat says 67 degrees.
So you're saying it would be fine to live in a thermos bottle as long as it had a good mechanical ventilation system?
I call that a house on CPR. Supports life as long as you keep pumping.
Riversong,
Isn't that what what you are doing with the bath fan/ range hood and Airlet 100 intake system- mechanical cpr? It seems to me like Frenchy is just being stubborn and filling his house with outside air instead of mechanically cycling it through.
I think your being a little too scientific questioning Frenchy on if he getting .25 ach/hr- what your doing seems pretty informal to me.
during the early '90's we used 1" foil faced iso on the exterior, and R-15 fiberglass in the 2x4 stud bays, our sheathing was 1/2 " cdx ply on the outside so we'd have a nailbase
as far as insulation goes, it worked great
i stopped using it for two reasons
second... we had to install lots of 1" blocking as a solid nailbase for windows, doors, corner boards, trim.....
and.. to get our racking resistance we were installing metal T-brace from sill to plate,
our BI pointed out that the literature from the mfr didn't cover us for the bracing we needed for RI code.... IE: it was not as good as a 4x8 sheet of ply in each corner
and the first reason we stopped is:
i went back on a couple of the jobs to do things like add a window... in EVERY case i found the iso completely infested with vermin..... carpenter ants, millipedes, and various unidentifed larvae
sine then the ONLY foam we use is EPS treated with borates
foam is a highway for insects.. it completely protects them and encourages nesting.. wether it's on the outside of foundations, or in the sheathing area...
i've also taken walls apart with Foamular & Styro SM... same thing ... full of vermin
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/26/2008 12:44 pm ET by MikeSmith
our sheathing was 1/2 " cdx ply on the outside so we'd have a nailbase
and.. to get our racking resistance we were installing metal T-brace from sill to plate
Why did you need T-bracing if you sheathed with CDX?
the ONLY foam we use is RPS treated with borates
I assume you mean XPS? What brand do you use that's borate-treated?
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Edited 2/26/2008 12:38 pm ET by Riversong
because the 1/2" sheathing is 1" away from contact with the stud so you lose your racking resistance unless you block ALL edges
blocking ALL edges would be counter productive
hah...i too wonder what RPS is ?????
nah, i meant EPS... ( beadboard )..... we use PerformGuard.. which we get from Branch River Foam in Smithfield
PerformGuard is a brand name of R-Control.. which has nationwide licensees... some jurisdictions , especially in the south, will only allow ground contact foam if it is treated...
you can get some brands of ICF's with Perform Guard
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/26/2008 12:48 pm ET by MikeSmith
Mike,
First, to clarify, we are using the iso foam on the outside of structural sheathing directly under siding, so the wood sheathing is attached direct to framing members. Windows and doors are anchored thru side jambs as well as nail fins and with the high density of the foam sheathing, this works fine.
Second, your comment on insect infestation is interesting. To this date I haven't seen that in our area and we have used quite a bit of the product over the years. I covered a house on a re-side project about 25 years ago, under aluminum siding, and have done work there recently, and seen nothing like that. I'll check into it more with our suppliers and see what manufacturers have to say. Is it possible some brands formula's may vary somewhat? Maybe my bugs have a different appetite than those RhodeIsland bugs.
i've seen bugs in all foam except the borate onesMike Smith Rhode Island : Design / Build / Repair / Restore
How about ICF's? We are currently using Nudura units, and I don't believe they are borate treated.
bish,
I do know reward forms ICF's are borate treated.
MR. Mike is FURR your northeasterners strapping ??webbing over ( under ) joists then FURRing perpendicular ( furring applied after webbing?
thanks John
yes.. i always debate with myself wether it's firring or furring.. i think the former
anyways... from the top"
joists
insul web ( aka : insulmesh )
firring ( usually 1x3 ) @ 16" oc
pull the insul web real tite and keep it running straight with no sags
the firring will keep it from bulging downMike Smith Rhode Island : Design / Build / Repair / Restore
thanks Mike
after I burn the last of our oil I'll be replacing a steam engine size boiler with a little gas unit & a huge impact for us is how it heats up our 1500 sq ft basement just being there
don't imagine the new unit will give off much heat at all so thinking how I'll insulate floor - this thread is right up my alley
Who was buying your Outback dinners after this superbowl?
cheers, John
jay was bsking in the reflected glory of the gintsMike Smith Rhode Island : Design / Build / Repair / Restore
yes.. i always debate with myself wether it's firring or furring.. i think the former
Furring: Strips of wood or metal applied to a wall or other surface to even it and normally to serve as a fastening base for finish material.http://www.nachi.org/glossary/f.htm
Unless you use fir for furring.
naturally..... whichever one i think it was.... its always the other one
i ever tell you about my theory of "A & B" ?????Mike Smith Rhode Island : Design / Build / Repair / Restore
frenchy, Thanks for the info. Does someone in your area stock them or do you have them shipped in? You're up in Northern NY if I remember right.
Bish
I'm in Minnesota and I bought them from my local concrete suplier Cemstone..
Mike, What brands of foam sheathing are borate treated. I'd like to check this out further. Thanks
the only ones i know of are PerformGuard by R-Control
http://www.r-control.com/performguard.asp
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/26/2008 9:16 pm ET by MikeSmith
Hey Mike,Can you help me find that thread of yours showing the cellulose in the crawlspace on webbing? I can't find it after several searches. Thanks Kevin
kevin... i don't think i've ever done cells on webbing in a crawl
the way we usually do crawls is to use EPS ( 2"), with drywall bonded to it
we stand it up around the inside, it goes from the footing to the bottom of the
subfloor
we notch around the joists, the void that remains on top of the wall, we drill thru the foam and blow with cells
you have to have a dry crawl to do this
if you decide to insulate the floor instead, then i'd install insulweb across teh bottom of the joists, and FURR the joists to provide more support... then blow the bays with denspak cellsMike Smith Rhode Island : Design / Build / Repair / Restore
"if you decide to insulate the floor instead, then i'd install insulweb across teh bottom of the joists, and FURR the joists to provide more support... then blow the bays with denspak cells"
That's what I'm talking about. I thought you posted a picture showing that, maybe I have you confused with somone else.
Hey Mike,I think I will do the dense pak cell for the walls, do you have a link for who you use? I've looked at the HD stuff, pretty cheap, but the coverage is based on loose fill in the attic. If it's dense packed it the cost per sq ft will increase. ThanksKevin
i buy all ours from InsulMart in Seekonk, Mathey get it from National Fiber in Billrica (?)....25 # bales.... about $8Mike Smith Rhode Island : Design / Build / Repair / Restore
thanks
I started to post about what dense pak actually means, and googled it instead. At 4 lbs per sq ft, you only get 5-6 ft of coverage per bag. With the install price you charge, how does it compare to the closed cell price of 1.85 sq ft at I believe 1 1/2" thickness?
don't know... we blow denspak at about 3 + lb/cfi don't know anyone who blows at 4Mike Smith Rhode Island : Design / Build / Repair / Restore
OK, which do you want answered?;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Don't understand your question? I was asking Mike for a brand name for the cellulose, and he gave me an answer. Are you responding to my initial question starting this thread?
Dazed and confused in Jersey,
Kevin
Hey, great discussion thread, all 99 posts. This is a topic I have been seeking input on for my next build and I have learned a ton. A few questions. Our code is R25 in the walls (mandatory minimum 2x6 walls for seismic) and R-38 in the lid. I know I can meet the wall code with dense packed FG batts or blown in dense packed FG. What is the R value of densely packed blown in cellulose and could this work? In general, how does the cost of blown in cellulose compare with blown in FG?Has anyone got a photo or graphic of Mooneywall construction? Sounds like a great way to deal with thermal bridging, but wouldn't it be cheaper to just install 1/4" foam tape (of the kind used between foundation and rim) between the framing and sheathing and/or framing and sheetrock? Anyone tried this?Thanks.
look for the thread "Mooney Wall"Mike Smith Rhode Island : Design / Build / Repair / Restore
timothyo,
This is a discussion filled with opinions. Some of those opinions are backed up by data however the source of that data is always questionable.
I've gone to some really official looking websites and read all sorts of information only to find out later that the website was a plant..
If you ask opinions of those here you will get some real bias.. (yes even from me) because we all have an investment to justify.. Some because it's their way of making a living and some because they've purchased one method over another and hate to be proven wrong.
The only real answer is a test you yourself do. You should be able to make a small (say 2'x2'x2') room with a variety of insulation and techniques. Put a small light bulb in as a heat source and set it inside a freezer with a thermometer in it over night.
Whatever has a warmer temp in the morning is the superior insulation..
Hey! Maybe that's an idea for an article in Fine Home Building.?.
Yes, the title QSort of a confusing bait and switch edit - I just now see this isn't a new thread
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Edited 5/2/2008 6:28 am ET by Piffin
so, given that it's an old question, and your interested in the topic, do you have an opinion? Come to think of it, didn't you chime in earlier in this thread, when it was current? I'll have to look back, if not, fire away.
The concentration within the cavity won't be able to rise to anything much greater than what is dictated at the temperature of the sheathing, the coldest spot. As I said, the sheathing will be the dehumidifier for the cavity.
Perhaps.
It depends on whether the rate of absorption & diffusion through the plywood is greater than the rate of diffusion through the drywall. If the outdoor RH is high, diffusion outward may be very slow. And if the indoor RH is high, diffusion into the wall cavity may be high.
I can imagine the humidity concentration increasing in the cavity until a dew point within the insulation was reached.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
"It depends on whether the rate of absorption & diffusion through the plywood is greater than the rate of diffusion through the drywall. If the outdoor RH is high, diffusion outward may be very slow. And if the indoor RH is high, diffusion into the wall cavity may be high.I can imagine the humidity concentration increasing in the cavity until a dew point within the insulation was reached."If the outward diffusion of water through the sheathing is slower than the rate of diffusion of water through the sheetrock into the cavity, then of course water must accumulate there. But with no real resistance to diffusion by the FG batt, the accumulation will be in the form of liquid water condensed onto and initially absorbed by the cold sheathing.I just can't see humidity in the cavity increasing much above what the cold sheathing will support, given the openness of the FG to diffusion.
I've read your posts, as well as others on this board, and wonder what your recommendations would be in my case. Saw by your profile you have been a member since January, so I'll assume your not familar with my project. I am restoring an 1880 beach house 1 block from the beach, on an island. The lot flooded twice since I bought the place in May 2005, and once more after the foundation was done, see picture, and the lowest point was directly under the house. I've lifted the house, put a full poured concrete foundation underneath with a dirt crawlspace. Foundation is 32" tall. I added 20 yards of sand under the house and 20 more as backfill. This now is the highest point on the lot so moisture from flooding would be in extereme circumstances, like a hurricane instead of a heavy rainfall. The first floor will be removed, plywood subfloor put down, underlayment and hardwood floor. The exterior is board and batten, blown in insulation, and beadboard as the interior surface. I plan on removing the interior surface beadboard, insulating and sheetrocking with mold tough sheetrock by USG. This will be painted or beadboard reapplied. The roof is not vented, I can see the 12" 3/4 thick boards which are the sheathing. We currently have cedar roofing which will be replaced with standing seam copper clad stainless roofing.So, how would you insulate this? *This whole project started with me starting a thread about the paint peeling off the house down to bare wood, and I was told moisture in the wood is driving the paint off the exterior walls. I've added some pictures, let me know if the last one is to large and I'll resize it.Thanks
Kevin
So, how would you insulate this?
Sounds like you're planning to leave the exterior skin intact, and I'll assume it's framed with 2x4s.
I would cross-hatch the walls with ripped 2x2s or flat 2x3s (what people on BT call the Mooney wall, but has been around before Mooney), insulmesh and dense-pack cellulose, no vapor barrier (humid environment, allow walls to breath in both directions).
Assuming flat ceiling, vent the roof with continuous soffit and ridge vents and add loose fill cellulose with air baffling at eaves.
Question: why didn't you raise the house on piers as they're doing in the Gulf coast, and let flood waters pass harmlessly underneath?
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
let me answer your question first: My house is the oldest in town, every lot and the road in front have been developed over time. My lot floods as a result of the neighbors and street runoff, low grade, and very high water table. Flood waters would not flow but rather accumulate and percolate down through the soil directly under my house. I had intended to improve the grade and do piers as you suggested, but the mason bailed on me. The poured continuous foundation was done for two reasons, the guy lifting the house thought it would make for a safer foundation and the guy forming the walls was more familiar with this technique. See attached picture of flooded lot. Note how water is around house.Now my questions:"crosshatch the walls" I assume like furring strips on existing 2x4's, a lattice of sorts. what spacing would I use?I'd like to leave the cathedral, exposed rafters upstairs. I could probably fill in between the trusses, bringing the ceiling of say, barn boards, down to allow insulation and a airspace above them underneath sheathing, vent at ridge and eave. Another choice would be spray foam. Spray foam guy said there would not be a need to vent roof if using there product, closed cell. Finally, would you use cellulose under first floor in crawl space as MikeSmith does?Thanks
Kevin
Is what I'm proposing to do(spray 1" of foam) and then strap, add mesh, and fill with cellulose OK?
Or; would I be better (economically speaking) to just add the strapping, mesh and fill with cellulose? Of course I'd have to add the styro baffles this way.
Doug
your wall section will have a higher r-value than mine
but yours will cost more.... you have to decide if it's worth it or notMike Smith Rhode Island : Design / Build / Repair / Restore
Ok, so there's probably a reason why this wouldn't be sensible, but I've got to ask.
What about squirting a thinnish layer of foam on studs and sheathing, and then infilling the stud bays with FG? Seems to me that the foam would stop moisture from migrating to the sheathing, thereby mitigating the need for a vapor barrier, and the FG would be a less expensive way of getting R value.
The only question in my mind is whether the foam layer would provide a condensible surface.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
someone posted something similar to your plan, believe it was DougU, read through the earlier posts. Thanks
There's more than one kind of foam... you might want to look into an open celled kind... Demilec is one.
" Its' one big drawback is that it burns like rocket fuel - and you really need to keep that from happening.
Another, less often mentioned, drawback to foam is that it is nearly impossible to change the wall later on. You can forget adding a receptacle or phone line that you forgot."
If the resident fire marshall hadn't added that second statement, I might take the first one half seriously.
If fire was an issue above other normal building materials, I can't see the stuff being allowed on sealed crawlspace walls, and under roof decks... attics in particular.
And, while remodeling may be tough, it's nowhere close to being impossible.
Upfront cost for foam is significant, but so are the energy savings and comfort upgrade.
I spent a lot of summertime at the Jersey shore of Stone Harbor and Ocean City, back when the only air conditioning was in movie theaters... put in the foam, you'll be glad you did... because as an added benefit, you'll hardly hear the next hurricane<G>
Winterlude by the telephone wire,
Winterlude, it's makin' me lazy,
Come on, sit by the logs in the fire.
The moonlight reflects from the window
Where the snowflakes, they cover the sand.
Come out tonight, ev'rything will be tight,
Winterlude, this dude thinks you're grand.
damm right I won't hear it, I'll be long gone. :)
Thanks for your imput.
Hey were doing a job now and everything was sprayed. How do you know the difference between closed cell and open cell foam? They sprayed all the cavaties chock full then cut it all back with a 3' sawzall blade. Does it scarfice some of its value cutting it back and exposing its "pores"? Any info anyone has would be great thanks.
Pretty sure the stuff that expands that much and needs to be cut back is the open cell, from what I've read and seen, closed cell expands minimally. Someone here will know for sure.
dockelly
I just reread your post from start to fiinsih, not once did I see a single attack.. There were some lively discussion and debates but no attacks..
remarkable on a subject filled with the potential for this much contention..
by attack, I guess you mean between all in the discussion and not me specifically. I did see some heated debate. It would be nice to have one clear choice, and it be the best choice. Life is just not that simple:)
dockelly
Yes heated debate but everybody seemed civil and had valid points to make. I didn't see a single personal attack.
everyone playing well together, who'd have thunk it!
Actually, I am impressed by how well everyone is playing together and how much builders know about arcane and technical(but important) topics in building science. I have a feeling there are a lot of other builders out there with graduate degrees gathering dust on the study wall.Here is my input. Up until recently, I have always gone with FG batts for new construction. You might say it is #### but it meets our code here in Seattle and I have never had any problems with it. Last project I got sold on blown in FG. I had a firm that would use a rapid machine stapler (1 staple per 2 inches of stud) put up a kind of tyvek veil over the studs. They would then punch some holes and fill it top and bottom with blown in fiberglass that would push out the veil about two inches in the middle between the studs. When you put on the sheetrock with screws, it would compress it perfectly. Great solution for a 20% upcharge over regular FG batts. Works really efficiently. Not much air infiltration and insulates well.OK, after the project was over the guy who had bid it for the insulation company called me to tell me he had made a math error on the bid. Instead of an extra 20% he should have charged me an extra 200% (three times normal batt insulation installed). (And yes he did want to be paid the difference-- LOL)Still and all, this amount doesnt really add a lot to the overall cost of a house and should be recoverable within a few years.A friend who is a green spec builder encouraged me to use her method which she claims is the most cost efficient for this climate. Spray in FG insulation (like I had done) but double FG batts in the lid laid at 90 degree angles to each other. She had done the research on the various foams available and said they didn't pencil unless you were living in the house forever.All of you seem to agree that fiberglass sucks and (if not using SIPS and ICFs) then you should use densely packed cellulose. I like the idea of using a recycled product. Also the DOE website shows cellulose superior in r-value. Loose cellulose is at R3.2-3.8 vs. loose FG at R2.2-2.7.What is not to like? Is there any downside here? Have any of you had problems using borate treated cellulose? Has anyone had a problem with mold?
Timothyo
Fiberglas has one fundamental weakness, which is air flows through it easily.. that's why most furnace filters are made with it..
Hot air rises, cold air settles.. so the warm air in the wall cavity will rise while the cold air on the outside will fall. thus you get a scrubbing effect with fiberglas that you wouldn't get with celluliose.. (air doesn't flow through dense pak celluliose very well.) I've not seen any problems with dense pak celluliose with one exception.. if moisture should get into the stud cavity wet celluliose doesn't have any R value..
If it's not possible then dense pak has it's merits.. It's made from recycled newspaper (treated) and should provide decent insulational value..
The weakness of course as you point out is the R value of the studs. depending on your climate that may be a serious issue or it maybe trival..
Thanks for your input Frenchy. So why do builders naturally use FG insulation rather than cellulose? Do you think that it might be because Owens Corning has a huge marketing budget and the guys who shred up newspaper for a living don't?I took down a house last summer that was chock full of 20 year old treated cellulose. No bugs, no rodents, no settling. The stuff was still in great shape although dusty as hell to take out.Anyway, I am going to start making some calls to get cellulose costed out. It is hard to believe that it is more $ for old newspapers and boraxo than for fresh glass fiber.The thermal bridging thing is my next issue. I like the mooney wall idea, but I still think that it would be better/cheaper to deal with it the same way we do between the foundation and the rim joist-- just install 1/4" foam tape. If no-one has tried this, then maybe I'll be the first. The only hassle there is that my framers are bound to complain of the extra step in putting it between the studs and the sheathing. The inside (taping between the studs and the sheetrock) I can do myself.
"It is hard to believe that it is more $ for old newspapers and boraxo than for fresh glass fiber."My installer will do either one I want for within a penny or two of the same price. When the price and the R-value are within 2% of each other, the decision is more one of personal choice and experience.
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timothyo,
It's hard if you've got a lot invested in stick building to break that habit.. I found that when I compared the material cost of stick building and SIP's the SIP's were cheaper.. Now I have several advantages..
First I bought factory direct.. No dealer mark up..
Second I hauled everything myself No frieght costs
Third I ordered them plain, No wire chases, no window cutouts etc.
Because of that I paid low prices for them, well under $3.00 a sq.ft. (2003 prices)
Now if I were building a totally SIP house I probably would have saved the added labor of cutting out the windows etc. On the other hand, I wouldn't have any of the labor expense of putting up a stick frammed house... Simply tip the panel up and the wall is done!
I've seen whole houses ready for roof trusses in a day with SIP's
On the other hand because I combined my SIP's with timbers and there was a considerable learning curve.
If I ever build another house I'd build it with ICF's. While there is a learning curve with them as well good suppliers will sell you forms and video's on how to build with them, then check that everything is really ready before the point of commitment (the pour)
I've watched experianced crews really fly through ICF homes. even when really custom stuff was done (such as a giant bowed front).
One built nearby with just such a feature was sealed to the weather in about 3 weeks. Stick building an 8000 sq.ft. house with that giant Bow would have taken closer to 3 months to weather in..
Now perhaps you don't need the ability to withstand a 200 MPH wind or need a 4 hour fire rating. Maybe termits and carpenter ants aren't an issue where you live.You aren't concerned about the thermal efficency of the walls. But the ease of building, hauling a pound of foam rather than a load of studs and pressing a spray can trigger rather than a pounding a hammer makes building with ICF's attractive when you add the durability of a ICF home which will remain standing far longer than most stick built homes will. ICF's should hold a real attraction!
"The thermal bridging thing is my next issue. I like the mooney wall idea, but I still think that it would be better/cheaper to deal with it the same way we do between the foundation and the rim joist-- just install 1/4" foam tape. If no-one has tried this, then maybe I'll be the first. The only hassle there is that my framers are bound to complain of the extra step in putting it between the studs and the sheathing. The inside (taping between the studs and the sheetrock) I can do myself."Adding an insulating layer over the studs will never ELIMINATE thermal bridging, only reduce it. The 6" of wood gives you a roughly R-7 1.5" wide thermal short-circuit through what otherwise might be an R-20 wall. If you add 1/4" of foam tape between stud and sheathing, you've added perhaps R1 to that R7. Big deal. The stud is still a thermal hole. Oh, sure, every little bit helps, but a 1/4" of foam isn't worth the effort. The Mooney wall concept lets the wall be an additional 1.5" thicker, with 1.5" of insulation (perhaps R-5 to R-6) covering most of each stud, roughly doubling the stud R value.
Edited 5/3/2008 6:43 pm ET by DickRussell
why would anybody waste time adding only 1/4" of foam on sheathing? Most I know of use a min of 1/2" but more often 1" +
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""Fiberglas has one fundamental weakness, which is air flows through it easily.. that's why most furnace filters are made with it....Hot air rises, cold air settles.. so the warm air in the wall cavity will rise while the cold air on the outside will fall. ""Test have shown that this is a myth when it is wall cavities you are talking about. Convection in a stud bay with PROPERLY installed FG batts is virtually non-existent. This does not mean that cellulose or foam may not outperform FG but it is not because of convection in the stud cavity.
They can't get your Goat if you don't tell them where it is hidden.
dovetail,
I wish you'd do a simple test yourself.
Make a simple stud cavity. fill it with fiberglas. seal it with sheetrock. Now hold it over a smoking source.
If smoke comes out the top we have air movement.. The rest of the arguement is based on pure physics.
Better yet You do the test you just described, take photos and post the results here would you .
I will go with the test results from the same people who proved that convective heat loss through FG insulation occurs only in the attic and can be stopped by overlaying the FG with several inches of cellulose. You of all people should know that while a nice sales pitch the furnace filter analogy is nothing but a sound bite. Broadcast by those who have a competitive product to sell.
Edited 5/3/2008 2:03 pm by dovetail97128
dovetail.
OK a simpler test? Grab a handful of fiberglas insulation and an air hose. Blow the air hose at the fiberglas and see if you can feel air flowing through it.. (OK it won't work if there is a vapor barrier <grin>)
Bottom line? Air moves through fiberglas. What fiberglas does is slow the air movement down to the point where heat loss becomes tolerable..
Myth when applied to wall cavities that are properly insulated.
They can't get your Goat if you don't tell them where it is hidden.
Dovetail.
I understand that air won't flow though foam (well, ok it will poorly through loose fill but not solid foam) I also understand that it doesn't flow well through celluliose but I have no trouble with air moving through fiberglas. Now if I were inside a wall and held my hand on the inside sheetrock I would expect it to be warm around 70 degrees or so depending on a lot of factors.. Conversely If I held my hand on the outside wall I would expect that to be around outside temps. let's say 0 degrees If we have typical 2x4 walls the temp differance between 70 inside and 0 outside wall would occur in that 3 1/2 inches of wall cavity..
OK Can I breathe? or will I sufficate? Can air get into fiberglas?
Frenchy, I am simply going to rotate my answers by alternating between my previous posts so unless you want to spend the rest of your life here reading the same response I would suggest you give up. Your choice of course. ""Test have shown that this is a myth when it is wall cavities you are talking about.Convection in a stud bay with PROPERLY installed FG batts is virtually non-existent.""
They can't get your Goat if you don't tell them where it is hidden.
dovetail
I accept that I cannot convince you. Provided of course that you accept you cannot convince me..
As gentlemen we shall agree to disagree!
I'm a fan of cellulose, but am always interested in new information.Do you have any links to the studies you mention? I would be very interested to read them.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Not the specific study you are looking for but something to chew on.http://www.buildingscience.com/documents/digests/bsd-011-thermal-control-in-buildings/?topic=/systemsapproach/buildingenclosure/wallassembly/insulation/main_topichttp://www.customhomeonline.com/industry-news.asp?sectionID=209&articleID=506597
Edited 5/3/2008 7:58 pm ET by reinvent
Right this moment no. I can tell you how I found it though.
I was discussing the convective loop in FG in attics with riversong and stumbled on the information that the same testing people that found that that convective loop could be shorted by use of applying the cellulose overlay tested the wall for convection and found what amounted to zero . I found the links to the test by following links off of a site for foam insulation that was proclaiming the link backed up their claim about the convective loop failures of FG. I will search for it , it may take a bit though. The thread was in the Energy folder here maybe 1 1/2 -2 months ago. I posted all the links in the thread.
They can't get your Goat if you don't tell them where it is hidden.
The installation you describe is called Bibbs - blown in blanket system. It is a dense pak type installation similar to densepak cellulose. The installers should have also used a roller to compress it in the stud cavity immediately rather than leave the bulge for your SR guys to compress.The R-value you cite in comparison to cells is referring to LOOSE blown rather than compressed. When dens packed, the difference is even less, a negligible amount. The price for installing either of these similar systems here is within a penny or two.I lean towards the chopped FG BIBs for a number of reasons.
One is that I have had to deal with a lot of cellulose in remodel situations and personally hate the cloud of filthy dust that it creates. Chopped FG clumps more like cotton balls and there is less fibre in the air.
There is also a perception that the FG is less likely to harbour and feed mold spores if the insulation ever gets damp for any reason. That may be unimportant in well done new construction where all systems are thorough and intact, but more important in retrofit work where the products are blown into older existing structures.Finally, I have three times seen cellulose burn. I don't know if this was because the cellulose from the seventies was not as well treated as the current generation or if the fire preventive treatment breaks down over time. I don't feel confident in the fire resistance claims in certain circumstances.Mike Smith is a frequent contributor here who favours the cells of the FG.Best of all is sprayed in polyurethene foam, but as the title here indicates, it is an expensive choice, tho I have not found it as expensive as the title indicates. I assume that is a comparison between installed foam and FG batts bought at HD and not installed.
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Now you've gone and done it! The oracle prefers BIB FG, the reasons you don't like cell are all situations I have, old structure, damp location, etc. The house had blown in FG from the exterior 20 years ago. We broke some of the beadboard trying to get a 16' joist in, I forgot to cut 2" off it's length. What I discovered was the inside of the exterior sheathing was covered with some heavy paper type product, probably to reduce drafts. This had come loose and fallen inside wall cavities, and FG was obstructed from filling properly. That's when I decided to remove the beadboard and re-insulate.As to the cost of foam, you are correct in assuming the difference is because of DIY FG vs installed foam. Apples to oranges, installed for both would be closer in price.On a side note, my local BI said spray foam for the underside of the roof was fine, no venting required, but I have to cover it with drywall.All this beefed up insulation may be a waste of time since I plan on leaving the old windows. I'll be asking for draft prevention techniques in old windows in my next thread:)Kevin
Without reading all (anny) of the responces...
"spray foam 10x the cost, why do it. " Exactly....
Matt
because it's not an apples to apples comparison. For example in my case I was able to buy SIP's for slightly less than the price of a whole stick built wall with Fiberglas insulation.. .
SIP's are massively more thermal efficient than stick built is, plus 200% stronger and infinitely faster to build with..
Now those numbers are closer to apples to apples..
You see the OP was assuming he'd install the fiberglas himself compared to having foam professionaly installed.. eliminate the differance between do-it-yourself and professional plus apparently he was having difficulty finding competitive quotes.
If you skew the numbers enough you can make anything look bad..
I spent $2180 to have 1460 sq ft of Icynene sprayed in about three years ago. Average utility bill was roughly $100 a month before that, now it is about $60. So I have been saving about $40 a month since then... let me see... 36 months times $40 is... $1440. So in another year or two my investment in spray foam will have paid for itself. And energy costs are only going to go up. The foam was professionally installed. I had fiberglass before that I put in myself (about $400 worth) that I tore out for the foam guys because it was still cold and drafty in here. Now it is nice and still and warm in here. So in my case the cost was about five times the cost of DIY. But really, I am comparing apples to oranges here the performance and installation differences between fiberglass and Icynene are worlds apart. I will never, ever, go back to fiberglass again (unless it is for use as a bass trap in a home theater, where it is left in the bundle and placed in built in corners covered with sound fabric to absorb some of the extra bass energy from a subwoofer. It clears up the sound).Edit for mispelling
Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK
Edited 5/4/2008 6:47 am by Pebble
One other comment. 10x the cost doesn't sound right. My insulator does Icine (spelling?) for about 2x the cost...
I started this post awhile back, I have to check current prices and get cost per sq ft comparison. But the number will always be alot less since FG is DIY friendly, foam is a professional job, the DIY stuff, like tigerfoam, is not much cheaper.
I know I'm jumping in late on this but consider using this system we have been utilizing the last few years with great success so far. Conventional 2x6 framed wall with Bio-Base open cell spray foam in cavity, 3/4" polyiso sheathing over structural sheathing in place of Tyvek for thermal break. The Bio-Base foam is installed in our area for about $1.85 per sq.ft., the labor to install foam sheathing is about a wash with tyvek labor, sheathing material costs are more than Tyvek but not unreasonable, and bridge all framing joints {such as between plates, headers,rims,etc.}. I feel this a tighter, superior system than our old standard of fiberglass batts, that has a pretty fast payback time.
Bish,
Have you looked seriously at alternatives other than stick building? Skip the labor to build walls and simply tip up SIP's or simply set in place ICF's
I paid retail for my ICF's and still managed to save over $10,000 over the lowest bid for foundation work.. IN retrospect I wish I'd gone all the way to the roof line.
Both systems massively decrease the time spent building.. both are superior to any stick built house when it comes to energy efficency.
The money saved can be spent doing nice touches to make the house better..
"I paid retail for my ICF's"WTF!?!?!?!?Just a few posts back, you stated that you had bought them directly from the factory and cut out the middleman profit to save money. Now you say you paid the factory full retail price but saved ten grand anyways?!Something stinks in this story.
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Piffin
Sorry, I should have been more clear. I went to the factory and explained what I intended to do. I asked their prices and I paid them.. I assume that was retail and not at a wholesale volume discount level.
So yes I paid factory direct prices and no I didn't go through a middleman who marked up the panels..
Now on to your claim that the freight cost you nothing.does your truck never wear out? Does it run on water or do you need to buy fuel and oil for it? Does your time have value, or is it without value and worthless?
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Piffin,
Well I would stop at the factory on my return home, load up with panels they'd make and continue home..
I suppose that I could have calculated the differance in coming home to the added wind resistance that those panels cost me. But since only a few miles were at higher speeds and most of it was driving around the lake getting to my home I'm really not sure exactly how much to add? 30 cents? 40 cents? a trip? The factory was about 35 miles away and about 8 miles of it was at speeds in excess of 30MPH. The panels stuck up past the cab by about 18 inches, and yeh they weighed something..
Be fair and I'll accept whatever number you assign.
OK?
As to my time? Well I was doing something I enjoyed. Not my usual work.. I've never calculated hobby time labor rates. So how much do you ask yourself if you want to hunt, fish, or play golf or whatever you do? What's fair?
We keep having this same go-round because you keep making outrageous claims that work ONLY for you. When somebody else is asking for advice and trying to measure costs, to make valid comparisons, they need accurate information.Same on the other side with the title of the thread. Spray foam only costs ten times asmuch as FG batts when the labor to install the batts is free and the faom is professionally applied to an R-value greater than can be attained with FG batts.
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Piffin
First if they are so outrageous why has nobody stopped by to see my copies of them? Several have been here and I'm more than willing to share my receipts with anybody.. I've got them right here next to the desk and older ones are even sorted into groups depending on who the vender is..
I do mention why I I paid the price I did.. I can't be the only person in America who lives near a SIP plant.. last I looked they were pretty well spread out around the country. I know I'm not the only do-it-yourselfer in America..
Your argument about outrageous comparison between professional installation and DIY I've agreed with you repeatedly.. I've said as much repeatedly.. one is done as a hobby/interest while the other needs to make a living first and then build and create.
I have no quarrel with those who choose to have a pro do it.. I offer my advice to those seeking to find a way to achieve what they cannot have done professionally..
Why do you constantly attack me for that.. I suspect we've had this same basic discussion 50 or 100 times over the years..
I've always been up front about my experiance, in anything other than sales I've never claimed to be a professional. (exception I did earn my living as a teacher /mechanic decades ago, if you go back to my youth I made money working on a farm, delivering newspapers etc.. )
I'll admit that I am astonished that I am able to achieve what I've achieved with no prior experiance, but considering my background that should merely make other DIY's more willing to attempt things themselves..
Frankly Piffin I think you're a bigot!
That's right, I think you resent or even hate those who do it for themselves.. Your whole tone is that we amatures can't do it as well as professionals can. Well that may be true sometimes.. (may not be true also, depends on too many variables to list here)
But DIY doesn't have to be a dirty word.. Next time I suggest someone visit a sawmill or look at SIP's or ICF's feel free to mention I'm a DIY if I fail to.. But don't attack me simply because I have a differant take on things than you do..
"That's right, I think you resent or even hate those who do it for themselves.."No - half my life has been spent helping DIYs accomplish their goals and as I revamp my business now, it is to focus on them more than others.The whole thing is to keep things in context for readers here. Without the constant reminders from me an others that you make outrageous claims that are so far from reality for anyone other than yourself, you would be freely making even more outrageous claims. I'm just keeping you honest so you don't forget all those things you tend to not include when you make your claims, so that readers can make valid estimates from their POV.
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Piffin
I just reread the whole series of posts, and I listed what I paid in general terms twice and put my disclaimer in once (post 148) In none of them was it an offer to sell or a bid price..
Now you are saying that I'm misleading people?
I don't see you make any disclaimers.. admitting that you're in it for the profit. Or how much profit you make so others can judge your value.
Your statement that I'm making outrageous claims is totally unfounded.. I keep calling you on it and you keep repeating it. It's time you knock it off!
I've spoken about this before.. How simple answers can get so wordy because of all the disclaimer people like you insist on.. If I generalize or gloss over something you're sure to attack me for failure to include it..
"Your statement that I'm making outrageous claims is totally unfounded."Sure thing! That is why any search for posts by frenchy here at bt can bring up hundreds of replies calling you out for false or exaggerated information.
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Piffin
Because I don't play the post a link game! My infomation isn't false! It's as accurite as possible. You simply refuse to believe that there are any facts other than your own world. Your own experiance in that corner of the country you live in is all you believe is possible..
You've never acknowledged that many of the posters on this site aren't doing it as a buisiness so we don't have to think as you do..
At least I acknowledge that there are other perspectives..
"Same on the other side with the title of the thread. Spray foam only costs ten times asmuch as FG batts when the labor to install the batts is free and the faom is professionally applied to an R-value greater than can be attained with FG batts."Not sure if I just got insulted with that comment, but I will say you and others on this board have been a huge help to me. I like hearing from frenchy, think he has some good ideas, but I think he's dead wrong when stating you don't like DIY guys (gals), I think you help pros and amateurs alike. I'm actually amazed by the patience you show, the mark of a good teacher.Kevin
no intent to insult either you or frenchy. just putting those statements in opposition to each other to maintain context and balance each other for perspective. Thanks for the comments.
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ok
I think we can all agree that there is a difference in cost between people who do it themselves and those that sub it out.I am building this house for myself, but I try to sub out as much as possible. I still wear a tool belt, but the best tool in it is my telephone. On any good size project, there is enough follow-up work and in-between-trade work to keep me plenty busy.You guys have all been helpful. I am going to do some research on SIPs with pre-made chases. Mainly I want to see if there are any framing companies in the area (with solid references please) that can frame up with SIPs. If I can find the right subs, I will give it a whirl.Short of that, I like the combination of things I can do with my existing base of subs. To whit:-ICFs for the Basement
-2x6+2x2 Mooney Wall for the Main & 2nd Floors with Denspak BIBB Cellulose
-Double Insulate the lid with R-38 batts at 90 angles (it is lighter than cellulose)I am not sure what the final R-value would be, but well in excess of code.Thoughts? Opinions?
Tim,
Let me make a suggestion when you post. Address it to all, not to me. It's as if your asking me what my opinion on your proposed building plan is, and I haven't got a clue as to what's best. That's why I ask so many questions here:) I'm pretty sure you intend the pro's here to respond, not me.
Kevin
timothyo,
Well First fiberglas isn't a great product according to virtually everyone here!
second Compare Mooney walls to SIP walls or ICF walls in price. All three will be relatively new to most builders.. you will be paying a premium for that.
Remember in the end.. the most durable wall is the ICF wall. I would ask my local cement companies who they use for work to get competitive bids..
Have them bid it floor at a time.. Don't expect them to pour all the floors at once simply to save you the $500 pumping fee..
The main reason for the FG is that it is lighter. If you are using trusses at 24 on center and half inch sheetrock, I am told it is cellulose is too heavy.I will cost all of this out and post the results online once the bids come in so we can compare.
timothyo,
So you're willing to accept an insulation that according to this magazine is as much as 1/2 as effective when it gets really cold. I'm a strong advocate for foam but if foam isn't possible please select a better alternative than fiberglas!
Plus if your ceiling is that flimsey that a pound or two differance will affect it perhaps you need to reconsider your structure. For example at a nominal cost you could intersect the 24 inch on center rafters with 16 inch on center studs.it wouldn't even have to be studs.. you could use those 1x3's for example. So the ceiling is 3/4 of an inch lower? If that's a problem I have solutions for that!
Moisture, any sort of moisture will add a lot of weight to either fiberglas or celluliose. My ceiling was 16 inches on center and still it sagged when the insulation got damp..
I'll assume your roof doesn't leak (mine didn't) but moisture gets into insulation in other ways.. for example those eve vents allow the dampness in the air (humidity) to get into the insulation and once wet either celluliose or fibergals insulational value is nil, Nothing, bupkiss! in the cold damp doesn't dry out easily.
That's the main reason my heating bills were as high as $500.00 a month during the peak winter months. Seven years ago before the recent increase in energy! in a house 1/2 the size with 1/3 the number of windows.. Today that same furnace heats a house twice as large with 3 times the windows for around a peak of $200 a month.. in spite of the energy price increases of late.
Thank you for hearing out my arguements.. I understand that in the end it is your house and you are the person who will live there. Do what you feel is correct in your application..
You know, I think you are probably right on this. I could order a few more trusses and put them closer together to get 16 on center and then do 5/8 rock up in the attic space. Not a lot of extra cost there.Still and all, I really hate the idea of loose fill cellulose up in the attic. I have done too many remodels where I ended up taking that stuff out with a coal shovel and I sneeze just thinking of it.Anyway,this is still all pretty preliminary. I still need to do the costing and that will determine the final outcome. On this job, I have determined that I want an outcome that is:
1) actually (not just theoretically) doable by subcontractors in this area in a work-flow pattern that makes sense
2) cost effective for this area, given weather and payoff costs here
3) as green and non-polluting as possibleYou notice the emphasis on what makes sense here. If I were building this structure in Fargo, Yellow Knife or Minneapolis, I might face really different choice-sets from Seattle. We are more worried about mold than cold here. We may be damned far north but we have only had two big snows in the last century (1917 and 1991) and both paralyzed the city for 1-2 weeks. The rest of the time we complain when it occasionally gets below 30 F. I met a guy who works in Nome recently and he was more than willing to give me information on ICFs, SIPs, sprayed in insulation and HRVs. Those are really the only technologies that make sense there and I would imagine they are worked into the code. Seattle (and the rest of us) will get there, but it may take a bit longer. Not too much longer the way energy costs are rising!One way or another, as costs come in I will post them and let you know how it looks so we can compare.
timothyo
Sad to say but I suspect given what you've given me I think you're stuck with regard optional building techniques.. If they are indeed as rare as you indicate you will be paying a premium. Not because there is a real cost differance but because contractors see them as a way to command a premium in an otherwise extremely tight market..
I did this research a couple of years ago and that is the way it was then. I haven't done the research yet, but I think it is still pretty much the same. I would sure be glad to be wrong.With this recession, it could be that people are hungry and so there are new options. That might be the silver lining on this particularly nasty cloud.On the other hand, I called for bids today from my two normal insulation subs and found the same person answering the phone at both. The two biggest insulation contractors in the area (Gale and Washington Insulation) merged last year. Between them they probably do 80% of the builder business in the area. Not a good sign at all
In the ongoing debate about about insulation efficiency and value, occasionally it is helpful to have updated pricing (which, I am told has dropped substantially in the last few months) to set in place some data points.This is in Seattle. Prices are bound to be different around the country. There may be better deals around here for all I know, but this seems like pretty competitive pricing to me. I got this from Burnham Insulation (425.881.2666). The young guy I spoke with, Jason Stephenson was really knowledgeable and used the 2" of UCCF + 3.5" of CL BIBS on his own house and thinks that is the best combination of price and performance. The foam seals the cavity adds a lot of structural strength to the structure while the CL is affordable and great for soundproofing.FG= fiberglass
CL= cellulose
BIBS= blown in blanket system
UCCF= urethane closed cell foamWall SystemR21 FG HD Batt 5.5 inch .47/sfR21 FG BIBS 5.5 inch .97 /sfR21 CL BIBS 5.5 inch .75 /sfR21 UCCF 3.5 inch 2.19/sfR23 UCCF 2.0 inch 1.82/sf
+3.5 R11 FG Batt R26 UCCF 2.0 inch 2.08/sf
+3.5 CL BIBSR27 UCCF 2.0 inch 2.07/sf
+3.5 R15 FGHD BattR30 UCCF 5.0 inch 3.21/sfR26 7" CL BIBs .97/sf
(for 6+2 Mooney Wall Attic SystemR38 FG attic Batt .84/sfR49 13" blown CL attic .55/sfR60 18" blown CL attic .66/sf
interesting....veddy interesting...
made up your mind yet ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Timare you saying the combination of the two insulating products is how the R value is achieved, and the per sq ft price if for the both?R23 UCCF 2.0 inch 1.82/sf
+3.5 R11 FG Batt
All of the information I have I got came from the insulation sales guy. He seemed to really know his topic not just because he sells it, but because he recently had to make some informed choices about how to spend his own money for his own house build. That counts for a lot with me.Have I decided? Not yet. More bids coming in later this week. But 7 inches of cellulose in a Mooney Wall System is looking good -- and pretty cheap. However, this is the Northwest and we do worry about our earthquakes here. About 5 years ago I lost my chimney during the Nisqually Quake. It fell into my side yard-- good thing we weren't out having a barbecue. For seismic, 2 inches of closed cell polyurethane foam and 5 inches of BIB cellulose would be pretty nice. Pricier though.What are your thoughts? Anybody want to chime in?
if you're giving the foam a seismic plus,
i think you have to get some seismic value from the 2x2 Mooney on the interiorMike Smith Rhode Island : Design / Build / Repair / Restore
Mike. I am not an engineer so I would have to check on the seismic stuff. With a Mooney Wall, it could be that the whole structure is actually weaker because you do not pick up the shear value of the sheetrock screwed to the 2x6's on the inside. I will have to ask my building inspector if this kind of thing is allowed given our seismic code.I do know that an offset (staggered) 2x4 wall on a 2x8 plate will meet code here. I know somebody here who built his house that way to cut down on thermal bridging.
All of the R-values are made up by combining what they are given by the manufacturers. These are nominal R-values.In this case, it is a combination of 2 inches of sprayed in Urethane Closed Cell Foam backed by a 3.5 inch R-11 FG batt for a combination R23 at a cost of $1.82/sf.The salesman had not read any of the stuff in these posts but basically feels R-values are not a very good indicator of insulating efficiency.For what it is worth, he sides with those who feel FG is inferior to CL. He is of the opinion that a combination of 2 inches of UCCF and 3.5 inches (or more) of CL densepak BIBB is the way to go. He has that in his house and loves it for 1) seismic peace of mind 2) wind/air blocking 3) sound deadening and 4) general insulating efficiency. He has a 2700 sf house and it is heated with electricity (no gas in that area of the county I guess) and he said he never pays more than $100 bucks for heat in any given month.
when I got a price 2 months ago, the closed cell foam for the interior walls was 1.85 for 2 inches, no FG, just foam. I'll have to call around, see what others are charging.
You are supposed to use 5/8" Sr when layout of framing is 24"oc anyways. Just the weight of the SR will cause sagging over time.
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I used to do 5/8 on the lid but now they have a special type of half inch SR for this application. No sagging yet!
Ney Bish
This is retrofit insulation, house is 120+ years old. I'll be removing the interior beadboard and will insulate prior to drywall. In a couple of years I plan on doing a freestanding addition and will look into current building methods at that time. I really like the SIP and ICF approach, as Frenchy has used.
Even though your's is a retrofit situation, you may want to check if there is an installer of Bio-Base spray foam in your area. Their prices were very competitive here, much lower than other spray foams. Even though the R value is lower per inch than closed cell foam you still benefit from the air sealing of the stud cavities and wall penetrations.
dockelly,
Foam can be a DIY job for amatures like me.. The only trouble is you need to start thinking outside the box.. forget studs and framming.. either build with ICF's or build with SIP's I did both and in retrospect extremely glad I did..
My heating bills were as high as $500 per month Using the same furnace in a house twice as large with 3x the windows They are now a max of $200 per month. IN retrospect it was cheaper to build with SIP's and ICF's (for me) than build stick frammed.. So I won/ won
your "foam" was done at the factory. I'm referring to the spray in place stuff, a retrofit insulation to existing home. I love the SIP's, next project, when I start a new building, I'll be taking a closer look at them.
Dockelly
I'm sorry I forgot the original was a retro fit.. but I still suspect your 10 times number Because my brother in law did such a thing and found a 15% premium over other insulation even done by the same contractor..
He choose this contractor because of his reputation and paid a premium for him only to find he no longer worked in the field but had sold the business..
He had bids that were lower. Hind site is 20/20 and he would have been better off using one of them.
However his energy bills were dramatically lower using the same boiler with a far larger house and massive increase in windows.
That was all well and good, what he constantly comments about though is how solid and quiet the house is now compared to when it was fiberglas insulated..
This was a complete remodel which in retrospect would have been cheaper to simply tear down and start new.
Frenchy,
I agree that SIPS and ICF's are great alternatives. I haven't used SIPS other than on cathedral ceilings, but we use ICF's extensively. I do find that it is more expensive in our area than the wood frame system I have outlined, and sometimes we use a combination of both systems in the same house. For instance, our most recent ICF home was ICF block to the roof trusses on the east, west, and north walls, and woodframe/foam on the south wall. This home was designed for passive solar with more window openings than wall area on south side. I've found ICF's to be a bit of a pain in areas with windows grouped close together. I may experiment more with sips wall systems in the future. I don't think any one system is the perfect answer for every job and location.
Bish well said,
My experiance is differant on costs but I've admitted why.. (nearby factory direct pricing and no frieght charges plus no extras such as window cut outs or wire chases)
I can understand where the first toes touching into the SIP field would probably have a differant experiance.. I think that SIP's are overpriced in part because of relatively little competition and part because it's percieved as a premium product and therefore should command a premium..
I watched my factory build my SIP's and I must say they were really inefficent.. I've seen stick built houses assembeled faster and with less wasted effort.. But these were all done not in the factory but at a nearby truss plant. They batch built them and the workers saw it as a day to goof off because seldom did they have enough demand to spend the whole day making them.
The equipment had to be hauled out and the panels assembeled. Then everything returned for normal business the next day..
I paid under $3.00 a sq.ft. for 6 inch panels and slightly over for 12 inch panels. Working backwards based on what I see, those panels if made efficently should be slightly over $1.30 a sq.ft. for 6 inch panels However to achieve those numbers more than 2% of houses must be made with SIP's.. competition must force the few manufacurers to see profit at that $1.30 number.. IF 50% of all houses were I think we would then start to see that sort of pricing..
It's a chicken and egg issue.. Same with ICF's too few plants making too few forms.. Too much expensive shipping involved. Little reason why every major city doesn't have several ICF plants competeing for the market.
frenchyI like the idea of SIPs, but unless you have your entire building planned and in CAD down to the last tiny detail, this seems problematic. If you use hydronics (with all those tubes) and if you put in a lot of low voltage systems (alarms, home theatre, speakers, intercom, etc.), this seems like a pretty time consuming process unless you build a separate 2x2 wall inside the SIPs for those systems. I understand your enthusiasm for ICFs. They make a world of sense to me. The problem is the learning curve. In my area (Seattle), it is easy to find concrete guys who will put in a first floor using ICFs (usually the basement) but they are not willing to risk going any higher. It is one of those things that falls in between residential and commercial specialties. They just don't feel comfortable bidding it or doing it.If you are using all ICFs for the walls, framers will not take the job if they are only laying floors and roof systems with long breaks in between for the walls to get done. So until we get crews who are experienced in ICFs AND framing, and are willing to bid the whole thing as a finished structure, it is difficult to do on a production basis. If you building everything yourself or have your own crew who you can train to do this, that is a different matter of course.We all tend to emulate those things that are successful and avoid those that are not. I have seen several all SIP or all ICF projects in my area that started out well and then just became an exercise in pain. Start, stop, subs walk out, start with new crew, stop, subs walk out, etc.Definitely a learning curve problem for builder and subs. But part of this problem is also that it is hard to go any faster than your local building department. A lot of our inspectors are really enthusiastic about "new" building technologies (they all seem to read FH religiously) but if they have not been specifically trained in a technology, you either have to wait for the inspector who has been trained or hire a private inspector to write them a report at $300 a pop. Talk about frustrating.You are right that it is a bit of a chicken and egg problem, but we are making progress.
timothyo
Well your problems are solved..
First with regard wiring. Nothing is simpler! Take a self feeding ships auger and run wires to your hearts content. You haven't lived untill you drill thru 6 inches of foam! I mean even weak wristed me (don't you dare call me limp wristed <grin>) can do it easily! If you have to go the length of the panel buy some of Milwaukee's extensions.
Aside from that if you're not crude simply order wire chases anyplace you want them. It's really too easy! I daisey chained wires in my panels putting light fixtures in and at most I had six minutes per panel. When finished grab a can of spray foam and fill the holes! No need to sit there and grind thru a stud with a dull drill bit..
Second there is no need for getting approval.. they are already approved and meet code etc.. At least reward system are. Your closest distrubutor is Wilsonville Oregon
ICCES UBC NBC SBC IBC IRC CCMC AIA/CES ASTM plus Maimi Dade, Florida, City of New York, Los angeles, Wisconsin, etc. etc. etc.. (those were as of 2006 I'm sure there are far more currantly)
go to http://www.rewardwalls.com for full details..
Frankly I'd talk to the form distributor to find contractors who are experianced and know how to do them. It's best if the form distributor and the concrete supplier are the same one.. then they have a interest in getting you the right stuff with the right people!
Finally with regard to panels, I ordered plain ones because it was so simple to field modify them to my needs.. It would be even better if I actaully had plans for my house.. but it's so simple to field modify panels I didn't worry about it.. Sure cad designed panels would be nice if you can plan that far in advance. So much faster to install windows etc..
FrenchyI am a bit of a fanatic about having really, really well worked out plans. In a previous life, I ran a manufacturing company and all our parts were worked out in CAD to the ten thousandth of an inch. No kidding. I drive my architects crazy because of the level of detail I want on my plans and I seldom change anything once I start building. So I should be a perfect candidate for plannned and engineered SIPs. I will call around and see what the state of the art is. Believe it or not, a friend of mine built a house out of SIPs in 1975. He is still living in it-- and may eventually finish it. His first year in the house the problem was not heating it, but too much heat (12 inch walls and 15 or 18 inch lid). Whenever they had a party, they would turn off the heating before the guests arrived and then open windows. Cooking, lights and body heat would drive the temperature into the 80's in the house.Thanks for your input.
"nearby factory direct pricing"And now in a third post, you are back to factory direct pricing after just claiming full retail paid.
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>> But the number will always be alot less since FG is DIY friendly, foam is a professional job, the DIY stuff, like tigerfoam, is not much cheaper. <<
Maybe - I've found that the insulation company can sell me the FG installed for pennies more than I can buy it for... If that has any bearing on things....
Another cost factor is health- I've never felt healthy after a day installing fiberglass. Then there's all the fiberglass dust that settled on the floors that get kicked up by the finish guns and wind that blows through the site. What is that savings worth?
Couldn't agree more. The post from Piffin describing all the dust associated with cellulose has got me thinking. I lost about 2 months work time at the house this fall due to respiratory problems I'm sure where caused by kicking up the sand dust while working underr the house. Had to go on a steroid inhaler for a month to knock it out. I won't be doing anything without factoring in the potential health problems in the future.
I remember watching a TOH episode about asbestosis years ago and thinking someday they'll tell us glass fibers attach to our lungs like that but they "just didn't realise it at the time"!
An architect from Cape Ann in Massachusetts came to our school to discuss his super insulation- staggered stud technique in '87. At that time he had stopped writing articles saying the foil on OC fiberglass was not a vapor barrior as stated- but we should notice the logo that was on it (American Association of Home Heating Oil Dealers or something like that)- He was threatened by OC that he'd be sued which he did stop. The powers that be surpressing information as usual.