I’m about to have a mess of additional insulation added to my attic area. There is already some old fiberglass that I intend to leave there. I believe that cellulose is the material of choice but after the recent talk involving Bibs (which is fiberglass, I believe) I’m wondering if fg would be the better choice.
I’m in the PNW, the attic is well ventilated, the roof is composition and brand new. I hope to dog that once this insulation is added that I don’t ever have to go up there again. I’ve seen enough of that space for a lifetime.
I’ll be contracting this work out to an insulation company. Any recommendations for my area: an island near Seattle?
Replies
Sap
Find David Meiland by doing a search in the MEMBER area-the button for it is up on the left in the box with your name on it.
He's from right there (somewhere).
Blodgett is from south of you.
Fiberglass has better self-promotion.
IIRC
you're on Bainbridge?
A good insulator is Coast Insulation, from Bellingham. Dunno how far they travel, but maybe call 'em.
Yep, I'm on Bainbridge.
What about the pros/cons of cellulose vs. bibs? Is bibs always fiberglass? Does one material perform better than the other here in our climate? Sorry, I got lots of questions. Ask something about cabinets, furniture, or concrete countertops and I can pay you back.
I'll contact Coast. Thanks.
Sapwood,
Regarding the pros and cons of cellulose vs. BIBS, I probably have the same questions, but I am still working on the pros and cons of BIBS.
I would only suggest you alk to your states Department of Energy as well as your local building departent for advice. There are reasons I say that since our code down in Oregon would restrict the install. of blown-in insulation..dependent on your attice space & roof pitch.
I Oregon we have the Department of Energy to speak with.
I have been wrestling with the same dilemma, I have 3 inches of wood chips and 5 1/2 of unfaced batt fiberglass in my 1000 sq/ft attic in Winnipeg Canada (thats abour R19 or so)...code here is R50.
I want to blow in another R40 and the more I looked at it and discussed it the more I realized cellulous is the answer to my insualtion problem.
Here, where it is -40 every winter the blown in fiberglass allows convection currents that effectively reduce the R vaue (because its loose with lots of airspaces...the greater the difference in temp between the heated space and the atmospher the greater the convection so the worce fiberglass performs.
fwiw the advice over on greenbuildingtalk seems very well thought out; like it does here :)
I can buy and blow R40 cellulous for about $1100 for my 1000 sq/ft roof. That will bring me up to R60..... in my case I have to add sheilds between about 1/4 of the roof trussess between the soffit and above thte insualtion to ensure ventilation is maintained.
I had a 1900 sq/ft home with R40 blown in fiberglass about 15 years ago and would never go that route again.
Fiberglass Convection Claims
Kenora,
I am not exactly sure I understand your experience with using fiberglass. There is nothing about fiberglass that causes it to perform less than promised. R-40 of fiberglass is a true R-40. I have heard others say that fiberglass does not prevent convection within the blanket. This sounds to me like a lot of other claims that are being thrown around on an absolute basis. An example of such an absolute claim is the claim that because fiberglass allows air movement, it fails 100% as insulation.
While fiberglass does allow some air movement, it certainly does impede air movement to a large extent. It would not work it if did not. And while fiberglass permits more air movement than closed cell foam, the R-values of the two types of insulation reflect the difference in impeding air movement. However, the air movement in fiberglass does not reduce its R-value below its R-value rating.
There are pros and cons to each type of insulation. For instance, both fiberglass and cellulose, when blown in, can be installed at unintended densities, and both can settle in a way that can either increase density or leave areas un-insulated. The biggest problem with fiberglass batts and is that takes great care to install it properly. The biggest advantage of fiberglass batts over blown fiberglass or cellulose is that the batts are manufactured at an accurately controlled density, and they do not settle after installation.
One thing that you should consider is that if you add cellulose on top of your R-20 fiberglass, it may compress the fiberglass. This may or may not be a disadvantage, depending on the amount of compression.
The point is that unfaced fiberglass can exchange a lot of air with an open area such as an attic (while in an enclosed stud cavity this does not occur). I've never seen actual numbers on the effect, but then about 80% of insulation "knowledge" is not backed up with any sort of rigorous testing, and in this case "common sense" seems applicable.
Insulation Knowledge
I would not necessarily conclude that existing insulation knowledge is not backed up by rigorous testing. It is just that the amount of insulation knowledge is staggering, and it contains errors either intentionally or otherwise. There is a lot of smoke being blown by the various competing insulation interests.
I am currently researching fiberglass batt, loose blown, and compressed board insulation, and it is not easy getting clear answers, even from the manufacturers. It is not rocket science, but it sure can get confusing.
As I understand it, the fact that the fiberglass is not walled in on one side should not change its effectiveness unless you are striking it with air currents that pentrate the blanket. If the open insulation is facing calm air, it should not exchange any more air with the adjoining space than would occur within the blanket by natural convection. It does not need to be covered up in order to slow the internal convection from transferring heat to the outside of the blanket.
Fiberglass does permit some small degree of internal convection that ultimately carries heat through it, but even though air can move through it, the air is somewhat encapsulated by the tiny air spaces between the glass fibers. So the rate of internal convection is much lower than it would be if no fiberglass existed in the cavity. So the fiberglass R-value accurately reflects the insulation performance as it stands with that small amount of internal convection.
Closed cell foam, for instance, more tightly encapsulates the air or gas in bubbles, thus preventing convection. So, compared to fiberglass, closed cell foam has a higher R-value which reflects its superior performance. But this better R-value comes at a higher price per inch compared to fiberglass. So other tradeoffs would have to be wieghed to deciced which to use.
KD
If you don't think there's convection in wall cavities (sealed both sides) or open to the top attic style, then you have not opened walls up or really come across "used" insulatioin. The black you see in the batts is not merely discoloration but filtered out dirt and grime. This dark stuff just didn't fall there-it passed through and was picked up by the fibers.
It is
widely understood that fiberglass performance is degraded in open installations. You seem like you want to talk yourself (and us) out of this, but don't bother... it is well established. How much degradation? Don't know if that has been quantified, but energy experts all agree on the phenomenon, and mostly recommend cellulose for attics.
Some thoughts:
I said that Fiberglass does permit some small degree of internal convection that ultimately carries heat through it. All insulation types permit the transfer of heat to some extent. However, if you listen to some people in the spray foam or cellulose blowing business, they would have you believe that fiberglass does absolutly nothing to impede air flow, and its use amounts to having no insulation at all. And if that weren’t enough, they will tell you that fiberglass always grows mold and is the only cause of all mold problems.
Regarding experts all agreeing that cellulose is preferable to fiberglass in attics, I can’t confirm or deny that experts agree on that. But I do question all claims. Experts seem to all agree that it is impossible to properly install fiberglass batts and rolls, so they rate fiberglass less effective because they know that it cannot be properly insstalled even by the most skillfull installer. Experts also agree that the insulation performance of fiberglass decresses when it is compressed, even though that simple conclusion is too simple, and obsures the truth about compressing fiberglass.
Regarding the issue of fiberglass performance being degraded due to being uncovered: You say that experts agree on this, but they cannot quantify the amound of degredation. How is it possible to confirm degredation, but not be able to measure it? What certainly would be degraded by a lack of covering fiberglass on one side is the R-value of the whole wall or ceiling structure because the covering itself provides some of that total insulation value. Even the air film on each side of the covering has some insulation value. So, if you omitt the covering on one side, you will have less R-value for the whole wall or ceiling section. But that would be the case with any tupe of insulation, including cellulose or foam.
The insulation itself only perfoms within its thickness. So if a lack of covering degrades that performance within the insulation, there must be air currents striking the insulation that would not be able to strike it if it were covered. If open fiberglass faces calm air, there should be no affect on its internal performance. But air currents striking open fiberglass will penetrate it and degrade its performance. I can see two ways that air currents could originate and strike open fiberglass. One would be ventilation air coming through the sofits, especilly if pushed by wind. Another would be air falling on it from the natural convection loop in the attic.
Regarding dirt and “crud” building up in fiberglass. Air currents striking fiberglass will degrade its performance, and also carry dust into the fiberblass and deposit it there. Without air currents striking fiberglass, the limited natural convection will also bring dust into open fiberglass. Gravity alone will also settle dust into open fiberglass. A defective vapor barrier or lack of a vapor barrier will let vapor condense in fiberglass, and wet it. Wetted fiberglass will grow mildew. I would suspect that black discoloration within fiberglass is mildew.
If I were using fiberglass to insulate an attic floor, I would cover it to keep the dirt out and to positively prevent air currents from striking it. Even if open fiberglass were protected from air currents coming in through the sofit vents, there will be some air falling on it from the natural convection loop in the attic. Covering the fiberglass is the only way to prevent that falling convective air from striking it. If I were using fiberglass in a vaulted ceiling, I would cover it with air chutes for the cold-side ventilation path.
If open fiberglass faces calm air, there should be no affect on its internal performance. But air currents striking open fiberglass will penetrate it and degrade its performance.
You're ignoring the effects of convection. In a heating environment warm air will rise up out of the insulation and draw in cold air from above, creating an air current even if none would exist otherwise.
Dan,
I am not ignoring the effects of convection. But I am focusing on how what is going on outside of the insulation layer might affect what is going on inside of it. This to address the contention that the internal convection of fiberglass is speeded up and therefore transfers more heat through the insulation if the insulation layer is not walled in on both sides. I agree that will happen if air currents strike the exposed insulation.
But the internal convection that you are talking about will go on no matter whether the insulation is covered or not. If it is not covered, the rising warm air will flow out and cooler air will drop down to replace it. If the insulation is covered, warm air will rise to the cover where it will conduct its heat out through the cover. Then once the air loses its heat by conducting to the cover, it will fall back down through the insulation layer. The same thing will happen if the fiberglass is in a wall and covered on both sides.
So in the absence of air currents that would strike the insulation if it were exposed, the only thing a cover does is add its own R-value depending on what it is made out of. Lacking any air currents, the cover does not add to the R-value of the insulation, and the lack of a cover does not subtract from the R-value of the insulation.
But the internal convection that you are talking about will go on no matter whether the insulation is covered or not.
Not at the same rate.
The rate will be the same if no air currents are striking the exposed fiberglass.
Whatever you say.
KD
whatever you install yourself, with your meticulous attitude, will be superior to the average installation
we've been installing our own since 1973...always using best practises
6 mil vapor retarder/air barrier ...carefully fitting edges, etc
until about 1985 we used FG exclusively...so that gave us a 10-11 year track record of going back and observing long term effects
long about '85 we started having cells blown in by subs...very impressed with cells
then about '95 or so, the state changed the Workmens Comp laws...and my sub told me he wasn't going to comply and would only work for homeowners
so...we bought our own blowing machine and started blowing our own...serendipity...
we do a much better job than the average sub...and we've continually tried to improve our insulation / air seal levels
there is no way bibs or FG batts can compete with dens-pak cells
there is no way loose blow FG attics can compete with loose-blown cells attics...the cells job is always superior to anything we could possibly do with FG
there is also another point that you haven't discussed....vermin
the best cellulose is made with borax...which will not support vermin
FG will support vermin...open any wall and you can see the evidence
there is no support association of any effective size to trumpet the benefits of cellulose....compared to the marketing done by FG mfrs..with national media advertising
cellulose is promoted by experienced energy conservation firms and individuals...they are not out there promoting FG...its always the ugly cousin never invited to the party
the big competiion is always between spray foam and cells
but to me, the presence of vermin in foam ( except for PerformGuard )...means that i will not be using it until they show me they have an anti-fungal /anti-vermin additive like PerformGuard uses
anyways...that's my two cents worth
Comparing insulation
Thanks for that input Mike. I am not necessarily opposed to cellulose, but insulation preference is not something that I intend to base on general application where all possible conditions will apply. My application will only be for new superinsulated house construction where I do the work, and as a recommendation to others who want to do what I have done. I can understand the advantages of blown cellulose in filling around obstacles, not supporting vermin, filling irregular cavities, and being easier to control installation quality than fiberglass batts.
But for my application, the vermin won’t get in, there will be no obstacles to fill around, no irregular cavities, and I will do a good enough installation job. If I were insulating in production, for new and retrofit, I would have a whole different set of issues.
For my application, I have not ruled out blown cellulose or blown fiberglass. For batts, I have to take some special measures to avoid irregular cavities. Blowing the insulation would eliminate that work if the end result were the same.
Right now, I am heavily researching this insulation topic. I have experience with fiberglass, but not with blown insulation or spray foam. But I am looking into all three methods, including deeper research on fiberglass batts and rolls. I have ruled out spray foam for my application. But I have been told that there is absolutely no way that anything can compete with spray foam. That may be true for some applications, but not for mine.
But let me ask you this: Other than the issue of vermin, what are the pros and cons of blown cellulose compared to BIBS?
BIBS
is an attempt by fg to emulate dens-pak cells..
http://www.bibs.com/
two things occur to me....first they can't compress the fg to the same density as cells...so air can move thru bibs more than it can move thru dp cells
second....fg is inert...but it has no additive like borax to kill vermin
a 3d thing..
fg is a glass fiber...the fibers will not absorb water...but they are a perfect condensing surface...so if moist air gets into the insulation...it is a given the the outer surface will be colder than the dew point...condensation will occur...the condensate will collect on the fibers, coagulate and drip by gravity to the sill
cells are hygroscopic...they will absorb and hold and disspate moisture until either until it becomes saturated....or drying starts to occur...in other words it can be forgiving....fg cannot
to put it another way...
fg sucks
BIBS
double post edit
i would say...
if fg were my only choice...i would use bibs over batts....every time
Some questions:
I see three designations for cellulose:
1) Dense pack
2) Wet spray
3) Loose fill
When you blow cellulose in, is that always dense pack? Or are there options to blow it in at different densities?
Is loose fill blown in or just dumped into cavities?
What are the R-values for dense pack, wet spray, and loose fill?
Which of these three types of cellulose installation is used for open cavities like an attic floor?
How is it installed in an open attic floor?
is commonly above 3 lb/cf
settled long term density is about 1.6 lb/cf....so you can see that dens-pak cannot settle
typically you just over blow in an attic....you use just enough air mix to blow the cells thru the hose...so if you are trying to get say 24" of settled density...you might blow 26"
to get dens-pak you need an adjustable air mix...lots of air....very little cells...you have to have either an insulmesh fiber to allow the air out while trapping the cells....same as bibs... or you have to have relief holes in the restricted area you are trying to compact
wet spray requires a special setup that mixes a glue/water mix with the cells....not much water...requires a drying time before it can be covered...experience teaches how to get the best mix of water to cells
if you google Mooney wall ....you'll see a lot of pictorials on blowing cells
Wet Spray I believe is used for vertical spaces like stud bays before they are covered. It's kind of like spraying foam, in that it sticks to the surface it's sprayed on. It also needs to dry well before it's sealed up.
Do a search in this forum for "Mooney Wall", and you will see the method Mike uses for Dense Pack, which is a way to insulate closed spaces. This is what you would do if you were filling the rafter bays of a catherdral ceiling.
Loose Fill is what you use in an attic. This is just a loose application over the floor of the attic. You also have to blow a little extra to account for settling over time. There are paper measuering tapes that you can attach to varios points in your attic that you use as the fill line.
Don't know if there are any R value differences.
Thank you
Thanks Mike and Paul for those answers. I will check out Mooney Wall. Regarding R-value, I have one book reference that says the R-value of cellulose does not change with density.
Mooney Wall question
I have looked at the information on the Mooney wall. Is blowing cellulose into a wall with open mesh on the interior considered to be dense pack cellulose, or is this considered to be loose fill cellulose?
Mike
Be prepared to back up your instructions with scientific data.
It relies too much on the individual (doing the installing) and there's no evidence to suggest that you can get that 3 lbs per every time. KD has constantly defended the absolute need for a lab backed testing system and constant repetition of those numbers in the field.
Is there a meter at the wand that can tell you real time how much cellulose goes by the nozzle? I think that is all that would pass muster for an install in his wall.
Can you fill a wall to the dense pack density in the case of the Mooney wall where the interior is not soldily backed by sheet rock, but only backed by the mesh?
Other than the fact the fiberglass doesn't deter rodents, it doesn't deter roaches and other bugs, it doesn't do the job it was intended to do very well, it can't be install correctly AND ITS LISTED AS A POSSIBLE CARCINOGEN, its a great product. I would never even think of blowing loose fiberglass in a home I was going to live in and my concern would double if HVAC ducts were in the area and covered by it given the likelyhood some flaw in the ducts would result in fibers being sucked in and blown about the house.
I am not worried about the possible carcinogen issue. Either it is or it isn’t. What is the difference between a non-carcinogen and a possible carcinogen? I would wear a respirator when installing fiberglass. Dust can cause health problems besides cancer. Most types of dust, including grain, coal, and sawdust can cause lung diseases. There are references that say cellulose dust is dangerous to health and that the fire retardant chemicals could be carcinogenic. There are other references that say there are absolutely no adverse health effects from cellulose. I would also wear a mask when installing cellulose.
In any case, I would seal the insulation cavities, so no fiberglass or cellulose gets into the living space. I would apply a vapor barrier with either type of insulation, so the cavity would be sealed. There are people who tell me I can’t make an infallible vapor barrier. They can believe what they want. I will make an infallible vapor barrier. I will also install fiberglass batts properly even though people say batts cannot be installed properly.
I would also seal out rodents and other vermin so I do not need to rely on the insulation repelling these pests. There are those who claim that fiberglass loses R-value as the temperature difference rises. Whatever is claimed, there are others who say otherwise. The fact is that people are making up claims and counterclaims about the competing insulations to promote their own interests. For my application, I have ruled out spay foam, lean toward fiberglass batts, but am considering blown cellulose and blown fiberglass.
What I haven't figured out is why you're asking questions here. You seem to have all the answers already, and don't seem at all interested in the advice and opinions of others (other than to criticize them).
A long time ago.......
I worked on a small crew, mall work-store building and outfitting. There were 4 of us. As the number of stores increased and opening day approached, it wasn't odd that we were split up and sent to different places in the mall after morning show up. Didn't see each other till lunch.
There was one (new to the crew) guy that cracked me up. He'd ask over prestart coffee how we'd go about doing something. We'd answer in some detail only to hear from him when we finished,
"well this is how I'm going to do it".
It got to the point where we would each look at each other wondering who was going to attempt to offer up an answer.
Well, one morning he was sent out with a boatload of slatwall (the grooved display panels) to a store to do the install. The start, finish and base ht. were all mapped out on the walls from previous layout. These panels aren't light (nor were they 25 yrs ago) and having finished our job, we decided to go give him a hand. We expected he'd probably had most of the first row down and could use the help lifting and mounting the second.
What a surprise to round the corner and look in the window and see what he had done.................
Most of the panels were mounted.
Downside, they were all run vertical. The grooves running up/down. Now there are vertical panels available, but not these.
Hard to hang the racks, brackets and displays.
When we mentioned to him that this was wrong-
"that's the way I always do it".
Spent the rest of the day unscrewing and rehanging.
The Reason For My Questions
I do appreciate all of the answers to my questions, and I am trying to consider them with an open mind. As I mentioned before, I am researching this topic because I am interested in it, and eventually intend to advance some ideas about energy efficient housing. However, I am not poised here with hammer in hand wanting somebody to explain what I should do next. I am asking questions here because I want to learn what everybody believes about this topic, and people here have beliefs about it. I am also asking manufacturers, suppliers, building code officials, and other builders what they believe about this topic. I am reading books and other references on the topic.
The reason I want to know what people believe about this topic is that, so far, I have found that there are lots conflicting views on it. Google any question about insulation, heat transfer, vapor barriers, and cold-side ventilation and you will get at least twenty conflicting answers. I am interested in hearing different views on this topic even if they do conflict with each other because if I discover why people hold the views they do, I can better judge which views make the most sense.
I may build one or more houses according to my ideas on this topic. I have already built one. Suppose I were to build a house, and wanted to learn how to insulate it. If I inquired about the various insulation options, I would not be able to insulate the house because every insulator would assure me that everyone else’s method would not work. When I see conflicting opinions about how something works, I want to find out which one is right before I believe it.
I have come to my own conclusions about some of this, but not all of it. So when someone addresses my questions with confident assertions about what I have not yet concluded, I may or may not be convinced. If I am not convinced, I want to challenge those assertions to see if they hold up. That’s all I’m doing.
kd
have you looked at passifhouse...or net-zero ?
i've seen a lot of net-zero...using sips... a lot of super-insulated houses bult with sips, spray foam.....dens-pak cells
i can't think or find any being built with FG
what kind of climate do you have where you live or intend to build ?
Mike,
I need to look deeper into net zero. I had kind of forgotten about that lately. But from what I gathered in looking to the brief extent that I did was that it was primarily intended to zero out the carbon footprint. And while superinsulation was a part of it, it also incorporated solar panels, and perhaps passive solar for heat.
I would build in Minnesota or upper Michigan copper country where it snows like crazy. The superinsulated house I built and live in now is in Minnesota, west of Minneapolis. My general approach would be to go thicker walls than what you get with 2 X 6 studs to get up to about R-40 to R-50 walls. And I would use parallel chord scissors trusses in a vaulted ceiling with 7:12 pitch. That would be R-75 to R-90. I am starting with everything I did with this house and continuing with the best parts and a clean sheet of paper. Generally, I would develop these ideas for wintertime heating climates and not for hot climates like southern U.S. Right now I am building all of these ideas in 3D Solidworks cad.
One of the biggest challenges with the thick walls is to come up with the most rational framing for the walls, corners, and the window and door tunnels. I have that perfected in Solidworks right down to the individual pieces, so I would not have to figure it out during the framing construction. I could produce a cut list and cut all of the pieces first without thinking about how they go together.
Mike,
Is the house in the separate photo where you did the teardown? It would be interesting to see more photos of your project. I am not up to speed in understanding Energy Star 3.0. I thought I would end up exceeding everything, but have to investigate lots of code issues just to be sure.
For air supply, I will use an air-to-air heat exchanger power ventilator. I have one of those in this house with fairly simple ducting. This one is made by Vanee, which I believe is now Venmar. For heat, I have hot water with a small gas boiler. I would use that again.
With superinsulation, the distribution of the heat can be simplified somewhat since the heat spreads out fairly effectively because the loss so small. On top of that, the hot water heat distributes heat relatively evenly in the first place. This house only about 1350 S.F. divided between two floors with mostly open space. What I am considering for the next one is 1112 S.F. on one floor with a full basement that size.
The truss maker designed parallel chord scissors trusses with 7:12 for both ceiling and roof. Outside of the upper and lower chords, perpendicular to them is about 40”. That allows 30” for insulation and a generous air space on the cold side. My existing house has scissors trusses that are 7:12 on the ceiling and 8:12 on the roof. I don’t think I want another two-story house. It makes everything so much more work, not only for building it, but also maintaining it.
I will look at that thread on the other forum. The scissors trusses do create exterior wall space above the windows. But I don't think it matters much aesthetically. All the window and door tops are at the same elevation. In the new design layout, I have a 7:12 roof with 36" roof overhang at the eaves, measured horizontally. From the tops of the actual windows to the bottom of the eave fascia is 25" vertical. From the top of the actual windows to the underside of the roof where it meets the wall is 45". So with some kind of window trim, I suppose there is about 38-42" of wall above the windows. I have a wide roof overhang on this house, and I am sold on that feature for the next house.
I don't know how this is going to be sized, but here goes. This was a heavy remodel that would have been a lot better off starting from scratch. For a while this was known as "the house within a house." But ultimately most of the original house went away. I worked off of the old roof to insulate the trusses and put up a pine ceiling, and then tore out the old roof and gables and tossed it all out the window into a big pile. What is left is the basement and first story walls, which are masonry tile. The original house had been moved to this site in the 1950s and a new basement was built for it there. What I retained was the basement and tile walls.
Before this project, I did a ton of work on the interior, moving partitions and rooms, re-framing and re-decking the first floor, putting in plank finish floor, replacing the entire ceiling with a timber frame ceiling decked with 2 X 6 Southern Yellow Pine T&G, re-wiring, and re-plumbing. Then after getting that deep into it, a couple years later, I had to go further to better make the first phase pay off.
good size
got any more ?
like eave views, or finished pics "