I am getting ready to have insulation blown in my attic. I would like to use cellulose because it is a recycled product. However, the insulation contractor that I have spoken with warns that it is more likely to have mold issues if it ever gets wet and that it is not as fire safe. Does anyone have any thougts or experience with this? I live in Montana so R factor is important- I wanted to get in the neighborhood of R48. Also, I have a brand new roof. Moisture should not be an issue…
Thanks, MontanaJ
Replies
Do you have any insulation in place now?
If not, I would put in 1" of sprayed closed cell polyurethane foam., followed by 10 " of cellulose.(R-45 result)
A. the foam will give you R-7 and seal the air leaks if a good installer.
B. sealing air leaks is more important than R-value
C. cellulose yields 3.5 R per inch, glass is about 2.5-2.7
D. cellulose is fire code approved, and not as dangerous to the lungs
E. neither fiberglass nor cellulose perform if wet...keep it dry
F. get a second opinion, sounds like you have a glasser only guy
Do you have any ductwork in the attic?
Hope this gives you some ammunition.
Paul
Paul- thanks for the thoughts. I ripped out ALL of the old FG insulation (all 3" of it!)because I had a weird mixture of old wiring that I wanted to totally upgrade. Bottom line is that there are now a ton of unused holes in my top plates that I had starting filling with Great Stuff.
I too was surprised when I called 3 different insulation contractors about blowing cellulose. They all advertised cellulose, but each one tried to talk me out of using it by saying that mold would be an issue. I am a former carpenter here in Montana and have never seen anyone use foam UNDER fiberglass or cellulose. I love how foam seals everything and have used it in my basement for the rim joists and concrete walls. My house is a 1930's cottage/bungalow and sure could sure benefit from being tighter.
I guess my only questions with spraying 1" in the attic would be how to handle penetrations like bathroom exchaust fan and furnace stack? Baffle or just seal away? There are no Jct Boxes up there any more, and all the can lights are IC rated.
Thanks again for your help! MontanaJ
Forgot to ask about ventilatoin. I have exposed rafter tails and an open soffit. Ventilaton has been achieved through the friese boards, a newly installed ridge vent, and 3 gable end vents. Currently I have installed those styrofoam baffles in plannnig to keep the cellulose from cutting off circulatoin. If I end up using foam will I still have a properly vented cold attic?
Thanks, MontanaJ
Yes, so long as you don't block the soffit incoming air flow. The baffles should preserve the gap. Understand, that the foam is blasted/sprayed with some pressure when applied. We had a den/garage wall sprayed prior to sheet rock of the wall ( a timing issue). Stapled kraft paper with the enclosed string scrim, to the studs to provide a backing to foam against.
It held very well, and no problem sheet rocking both sides at a later date.
Sounds like a very well ventilated attic.
If you had not already installed the baffles, I might have suggested spraying the first three feet of under side roof decking along eaves with
1/2" foam to lessen ice dam potential. But with the roof vent and gables, you should have good airflow up and away.
PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home
With ten or twelve inches of cellulose or chopped FG, you shouldn't need any ventilation if you have sealed all those thoer penetrations.
The sealing job is why PH recomends the3 foam first.
My preference is for all foam but he makes a good point that the hybrid he sugfgests is less expensive - if you can find someone to do it that way.
You apparently connected the idea of getting water into the cellulose with roof leaks from the context you put it in, but you ar emore likely to get wet attic cells from interior moisture rising through, so the primary blanket of foam is good.
If the customer cannot afford all foam, I'm not particular whether I use cells or chopped FG. In your extremem climate, FG batts are almost a waste of time.
Either will burn if exposed to hot fire. When I was a volunteer fireman and doing occasional insurance repairs, I saw several fires involving both, buit in every instance, it was more due to careless installation - no shielding at lights, chimneys, fireplaces, or other hot spots, so make sure that he uses shields whether it is cells or FG that he blows..
Excellence is its own reward!
Hi,
I just had it done in my house in NJ. The contractor who does all other types told me it is the best type to have. My brother does marketing for a cellulose company, he said "BE SURE TO GET THE STUFF TREATED WITH BORIC ACID ONLY"!!!! The other types will invite mold.
Just passing it on.
Bill
I'm not aware of any cellulose on the market without Boric Acid/Borates. This is part of the standard insect and fire resistance package.
I have seen insects happily nesting in fiberglass, but the borates in cellulose will kill them.
Regarding mold:
Less moist air moving through cavity = less water condensing in cavity = lower chance of mold. Advantage cellulose!
Regarding fire:
Less air moving through cavities = slower flame spread through stucture. Advantage cellulose!
Cellulose insulation will not burn. Try it yourself! This is a huge misconception in the marketplace.
If you want to read the "spin" from a company pushing fiberglass insulation, look at:
http://www.fortressinsulation.com/faq/faq_difference.htm
Wow! They went all out! Good stuff. Thanks.
Even they admit: "Most kraft and foil facings on fiberglass insulation are themselves combustible."
Try that one yourself too. I have!
No I agree it is great stuff. But I disagree in term of the only ingredient in the cellulose insulation is Boric. I just called two weeks ago, the local guy who installed the stuff did not know what was in the insulation. He gave me the name of the manufacturer and I called them. They told me they do make different kinds with different treatments. I can't recall right now the name of the other ingredients but not all of them just have Boric acid. Promise
Bill
Thanks for the correction.
To be more accurate, I should have said that I have not personally seen any cellulose for sale without the borates.
csnow,
I want to correct or clarify two errors in your statement if you don't mind.
The manner that Borates killl insects is this; when they ingest the element in or on their food, it paralizes and destroys their digestive systems so they starve to death. It is not a chemical poison that kills by contact. By implication then, the insects that do find their way into the cellulose do eat some of it which is why they do not make their homes there. If they chose not to eat the cellulose with it's sweet taste, they could nest as happily as in FG.
Cellulose will indeed burn. I have seen it do so in three separate instances;
One > In insurance repair work, I was called to take care of problems caused by a fire started in cellulose. The installer had blown the attic with no attempt to shield the metal chimney from the wood burning stove. The metal chimney itself was entirely properly installed. The support box kept the first layer of FG the requirted 2" away from contact with the pipe. ( I don't recall whether it was triple wall or solid pack. I thinkj it was metalasbestos) Then the HO contracted an installer to blow an additional six inches of cellulose on top of the FG. He stated that he specifically asked the guy if he would be shielding the chimneys and was assured that this would be a standard part of the job.
But we all know how hacks do their work when nobody is looking over their shoulder. He blew it tight around the pipe too. That is where the fire started. It charred the trusses and the water/smoke damage to the house was greater than all the charring. I removed a five gallon bucket of blackened cells from the immediate area.
Two > I was part of a crew hired to go into the attic of a jail to do some welding. The building was metal welded construction with blown cells in the attic space. Because the mechanicals were located in that volumn, they needed regular maintainance but the janitor didn't care for wading through all that grey stuff.
So to overcome the faulty design, we built a catwalk above the insulation layer.
Laid down some blankets to catch sparks and slag and we kept a water bucket up there to douse hot spots but...
at least thjree times in the middle of the night, the smoke alarms went off and the contractor I worked for was called out of bed. These spots would smolder and smoke without throwing up a flame, but they were burning nonetheless. The worst one was a spot that somehow never caused an alarm to go off. When I went up in the AM, the place was filled with smoke enough to choke you and there was a fire hole the size of my head carred all the way around and a red glow spot the size of a fist still going at it.
I think the greatest danger in something like this is that if there is any debris mixed in,(yes we have all seen that too - discarded candy wrappers or sandwich papers) and a hot spot gets to it, there will be a wick to show flame.
Three > a couple of weeks ago, I demoed an old addition to the place I am working on. I burned the debris, including throwing bags of cells on the hot flames.
If there is a hot fire going, it will incenerate the cells.
I agree that irt will choke the fire pout for lack of convection in most installations.
But one of the great problems in that trade is the installers. They get to do a very hot and nasty job. Human nature takes over and they take shortcuts. sometimes they blow it in lighter than it shpould be and not packed. Sometimes they skip a setup step and fail to shiled heat sources.
Not trying to pick a fight, but a blanket statement that it will not burn is simply not correct.
.
Excellence is its own reward!
"I want to correct or clarify two errors in your statement if you don't mind... "
Piffin,
Good stories.
Thanks for the careful insight.
From your post, a number of things stuck with me.
One is debris. The amount of flammable debris I see in attic spaces is impressive. Never really thought about the fire potential, but it must be a significant factor.
Also, when I said cellulose does not burn, I should have said it will not support flames.
Lastly, anyone else following this thread should take note of the danger of insulation contacting flues or chimneys.
This month's TOH Magazine has a big color picture of FG insulation being stuffed in the gap around a masonry chimney!
http://www.thisoldhouse.com/toh/knowhow/repair/article/0,16417,518080,00.html
View Image
Huh! And I thought the proper way to block that cavity was with galvanized sheet metal! Who knew?
Andy Engel, The Former Accidental Moderator
I'm genuinely worried about the consequences of this article, particularly in TOH, since old houses are much more likely to have marginal chimney situations to begin with.
IRC1001.15 Chimney clearances. Any portion of a masonry chimney located in the interior of the building or within the exterior wall of the building shall have a minimum air space clearance to combustibles of 2 inches (51 mm). The air space shall not be filled, except to provide firestopping in accordance with Section 602.8.
Edited 10/27/2003 1:46:50 PM ET by csnow
That photo is funny except for the faxct that so many DIYs will do it just that way. One fire we responded to on the volunteer fire dept was from just that scenario, and since it was in a low eave space with almost no access, the roof got all torn to crap getting to it to use enough water to quench the heat- and ruining the ceiling and the carpet below.
Cellulose is "resistant to flame spread" to a measureable degree but not firePROOF. That difference is where peolple get off on the wrong track. The resistence combined with the control/limitation of air convection makes it a good choice but it is not as fireproof as masonry or metal as some people treat it.
I think we're on the same page..
Excellence is its own reward!
Hi Piffin,
Not trying to hijack Montana's dicussion, but I would be interested to hear your opinion of blown mineral wool insulation vs. cellulose and fiberglass. Saw a segment on TOH that it was coming back into favor after many years. What really impressed me was the sound control. They dropped a smoke alarm into a 5 gallon bucket filled with mineral wool and then dropped another piece on top of it, couldn't hear the alarm any longer.
Jeffrey
geeze, I've got another chink in my armour.
I don't know a thing about mineral wool beyopnd having removed it from a few remodels dating from the fifties..
Excellence is its own reward!
Ah, yes, mineral wool... Seems very common in old houses in my region.
My pyro tests show my samples of this stuff as completely impervious to fire. Even tried a propane torch.
My understanding is that any number of blended materials were used, including volcanic rock, slag, and ceramic fibers. Obviously, this stuff has already been 'burned' to a greater extent than any house fire can muster. This is reprocessed waste from steel mills and foundries. Some blends have glass fibers mixed in. Some old blends were reported to contain asbestos. Some types have little shards of something perfectly designed for sticking through cotton gloves and into your skin.
When you put it in plastic bags for disposal, the bags tend to fall apart from the millions of little perforations. Instantly clogs any vacuum filter. I have taken to using a 'wet filter' I devised, which is similar to those modified 5 gallon pails marketed for drywall sanding dust. The difference is a larger intake hose. A little water misting can help keep the dust down. Even a little whiff of the stuff will send me into a coughing fit. Respirator is essential.
I have heard rumors that mineral wool is making a 'comeback' play by getting into the 'wet spray' game.
I try to follow this stuff and I haven't seen any articles associating cellulose insulation and mold. Cellulose and mold, yes, but not the heavily processed and chemicalized insulation.
I have been told by several firefighters that they don't like cellulose because it makes their job harder getting everything out after a house fire -NOT that it makes the fires more likely or worse, just that it is harder to finish the firefighting job.
There are a number of siters "debunking" mold concerns, but they are all from interested parties.
See, e.g., http://www.cellulose.org/cellulose_mold.html
_______________________
Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....
As you probably are finding out, there are many differing opinions regarding insulations. Here are a few of my observations:
I find in my experience and investigations, that cellulose blown -in is a very effective air infiltration barrier. It will fill every nook and cranny and blow out the most miniscule of openings. It is not a vapour barrier like a spray on urethane foam, but I am totally against that concept. You want to minimize air infiltration, but not prevent breathability. That with proper ventilation will eliminate most mold growth environments. I have seen more mold problems with fiberglass, both batts and blown-in and foam insulation than with cellulose. But again the more critical aspect is ventilation.
I remember seeing a video clip of identical setups, with cells, fiberglass and foam and a fire starting. The foam and fiberglass insulation soon melted (for lack of a better word) creating a chimney affect in the newly vacant wall cavity and greatly accelerating the fire. The cells retained its effectiveness as a fire barrier well after the other two structures were in flames.
The biggest problem with cells from my observations around the country, is the lack of uniformity of product, especially of proper fire retardant mix. Without it, cells are highly combustible.
I find it admirable that your interest in using cells because it is recycled. But cells in my opinion is the far superior insulation for walls, attics and ceilings.
Dave, I'd bet that properly packed into a cavity, even untreated cellulose (which you can't buy as far as I know) would perform better in a fire than would FG. No air, no combustion. It might smolder, but I doubt that it would provide a path for the fire. Think of throwing a stack of newspapers on a fire. It takes a long, long time to burn.Andy Engel, The Former Accidental Moderator
Andy, you may be right. I have no evidence to support that thought, so avoid giving that impression . Since the cellulose is shreded, even properly packed, there may be more of a fire danger, especially along any exposed edge. This may be more of a problem in an attic rather than a wall as I was talking.walk good
Just a bit of qualified speculation. Another test that's fun to do is to get a good bonfire going. Throw on a shovelful of cellulose and observe. Then throw on a FG batt. Actually, you should do it the other way around, because the cellulose might put the fire out. <G>Andy Engel, The Former Accidental Moderator
I think it was Mongo or Mad Dog that built 3- 8x8 "houses" insulated with fg ,cells ,and some other . Then set them on fire ,with the same amount of excelerant. The cells insulated took the longest by far to be consumed with flames.
everybody talking about fire in the attic. It really doesn;t matter what up there if it catches fire the house is gone. so fire prevention is the right deal not just paper or glass.
Whoa nelly, a fire in the attic certainly doesn't have to be the death of a house. Our experience has shown that the blown insulation, whether it is glass or cellulose, protects the framing systems better than batts. Once again, it's all about air movement around the batts and the fact that the tops of the joists are exposed to the flames.
My question has more to do with spray foam. As an insurance repair contractor, we see a lot of fire restoration jobs, and spray foam really worries me. We have not ( in our 70 years of being in business ) yet done a fire restoration to a home with spray foam. Have any of you attempted to remove several inches of foam from a stud cavity after it has cured ? Once this stuff has gotten smoked, I would bet it would need to be removed. Fiberglass and cellulose are a piece of cake. Foam seems like it would be hellish to remove. Any knowledge of the flammability of the foam ? How about the smoke from burning ?
carpenter in transition
Hello all,
thought I would join in too, posted a similar question earlier, trying to get as much input as possible---not difficult considering the range of views in evidence.
I too am renovating a 90 year old structure, a school house in eastern Ontario. Impractical to remove the planking that covers the studs on the interior---lathe and plaster enough of an issue already---would like to insulate walls and ceiling and also felt that cellulose was the product of choice but concerned about air/vapour movement in this rather airy structure---balloon-frame, brick veneer, 2x4 studs and 1" rainscreen between plank sheathing and brick. Do I potentially cause big problems by insulating with cellulose blown down from the attic into the stud cavities? Can/should I attempt to seal from the interior with a VDR rated paint, caulking and foam gaskets where I can reach?
Also, if cellulose is the route, has anyone installed it themselves? Is it a feasible DIY project?
Sleepless in Perth
Cellulose, I believe, is the optimum material for you to use. But forget about blowing in from the attic plate if you want to achieve a proper job. rather drill 2-3" holes in every stud bay starting about 2' from the floor, then 3' centers up the wall. Usually this means one hole in the middle and the top hole at the ceiling. Start at the bottom and fill each bay up through the holes. When done, the holes can be replastered.
Cellulose will find any openings so be sure you check your floor framing. Ballon framing will usually find your studs starting at the mudplate with the floor joists open. Same with second floor joists.
I find cellulose much better at handling moisture vapour than FG. It may absorb moisture, but by it's nature allows the moisture to wick out and transpire the moisture through the wall, especially after the dew point is reached. With FG you will find water condensing and collecting in your wall plate because FG doesnot absorb water.
If your outside wall is breathable (ie. sheathed with wood boards rather than plywood ,OSB, or other impermeable products), then this moisture can move to the outside. Your wall should be fine having that airspace behind the brick.
The other consideration is to paint your plaster walls with a vapour retarder primer and caulk all outlet, switchboxs and other penetrating points.
You can do it yourself by renting the proper blower unit. But you stand the risk of an inferior job until you get the feel for the machine. If you have a wall section open, you can cover the inside with reinforced poly and strap it and follow the same technique to check your work.walk good
Thanks for the input, can't keep up with most of these conversations when I only check messages once a week if that...project going well so far, hoping to get away with insulating from the top after finishing because need to time for energy inspection for Federal Govt program without measures taken...trying to fit all into the two months left for completion