blown in fiberglass or cellulose
surujunah
| Posted in Energy, Heating & Insulation on
we have an attic insulation replacement situation due to a rodent infestation. going to blow in either fiberglass or cellulose, to the equivalent depth of r38. air quality inside the home is a big concern for the client. of course, install will be done carefully to limit dust. but for long-term presence in the home, does anyone have info as to which option is cleaner and greener?thanks
Replies
Greener? Obviously cellulose.
You might want to go to building science web site to determine and recieve the latest!
The industry is beginning to move away from fibreglass.
"industry is beginning to move away from fibreglass."Huh????Around here more and more are moving TOO FG and away from cellulose
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I can't understand that. Obviously they are not aware of how much lack of insulation fibreglass is compared to cellulose or foam.
within 2% of same as cellulose. Doesn't attract humidity from the air in this climate
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Both are reasonably clean and "green". Cellulose, of course, is generally made from recycled materials. (Maybe FG is made from recycled glass -- dunno about that.) Both are somewhat nasty to go "swimming" in, if you have to crawl into the attic, but FG is worse.
Probably cellulose is a bit more likely to sift/track out of the attic after someone goes up there for whatever reason. But cellulose is easy to clean up while FG can be a pain to clean up and get off of clothes.
In a typical retrofit situation in a pre 1985 or so structure, cellulose has the advantage of helping reduce infiltration more, increasing the effectiveness of the insulation. And there are good reasons to believe that the R value of blown FG in an attic is over-estimated, since it does a much poorer job of controlling infiltration in the insulation itself.
I don't believe you get much infiltration in an attic. That is something that is an issue at soles, sills, and fenestration points of windows and doors, etc..
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Depends on the era of construction, and how much sealing has been done since then. Leakage can be extensive in some cases, and sealing all the problem areas is not always easy in a low-pitch attic.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
still, you might have some exfiltration in an attic, but no infiltration
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Same difference. If air's going out at one point it's coming in at another.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
If the existing insulation is being removed, then perform air sealing before new insulation is blown in.
Definitely go for cellulose. And go higher than R38. Both heating and cooling bills will be reduced.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
Of course, we have no idea where this house is. Could be in San Juan where they don't bother with heating OR cooling. Or even windows you can close, for that matter.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
the house is in seattle. i think i would opt for cellulose personally- from what i've read, but the insulation contractor insists that it compresses over time much more than fiberglass. and also that the fire retardant chemicals in it make it more toxic than fg. ultimately, he will install what i want, but i would love to come at it with good information. thanks for the responses.
Make sure to blow in more than required, so you get your R38 after it settles. I'm having an issue with that now. I'm thinking of going with unfaced batts because the insulation blower is going to be expensive. With the batts, I can just buy several rolls at a time, and do it at my convinience. I second the air sealing suggestion. That was one of the first things I did when I bought this house (might be why my insulation has oversettled,too). I didn't live here long enough before sealing to see a difference on my utility bill, but it knocks the "dank" right out of the air as well as limits the chance for mildew in the attic.
Both will settle, and the cellulose will settle a bit more. Which is why you always blow in more thickness than the final amount you want.If the guy you're talking to doesn't want to do it, he probably doesn't know how to do it right, and you should find a different installer.The fire/insect retardant in cellulose is generally a borate compound, which is about as innocuous a chemical as you can come up with. It doesn't off-gas, it's not a contact hazard, it's not (unless maybe they take to eating massive amounts of the stuff) a hazard to pets.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Depending on where you live, you can get cellulose at a Lowes or Home Depot. If you buy a certain number of bags, they rent you the blower for free. For installing in an attic even a caveman can do it. If you can vacuum up stuff with a shop vac, then you too can blow cells into an attic.Heck, you could just bust open the cellulose bags and rake the stuff around, breaking up the clumps as you go.Don't even bother with fiberglass in any form.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
You install the compressed R-value depth which is part of the manufacturer's specs. You install e.g. 15" to get a settled depth of e.g. 13".
I dunno about the 'toxicity' of the chemicals in cellulose. Used to work in a place that made it. We shoveled in the chemicals ... no special protection was used (this was in the 70s).
I'd go cellulose. As one poster said ... the fiberglass R-value is rated w/out the affect of air leakage/movement, so may be a bit overrated. In a hot box test, it will have NO affect of air movement through it ... the 'perfect' construction installation ... which in an attic simply doesn't happen. Cellulose is a bit more dense and tends to limit air movement, naturally.
Cellulose recycles what would otherwise be thrown away ... newspapers. Relatively speaking, I'd bet the cellulose is much greener than the FG.
Your insulation contractor doesn't want to do cells. Maybe he doesn't know how, maybe he doesn't have the equipment, but he's definitely full of sheet.
Cells are installed to a depth that yields the chosen R after they settle.
Doesn't matter how much they settle if there is enough there.
Same with blown in FG, same principal.
ultimately, he will install what i want, but i would love to come at it with good information. thanks for the responses.
I'd say look for someone else, if this guy does cells because that's your choice he's probably not going to do it right.
Joe H
Cels is sold by the SETTLED thickness. And you are suppose to verify the amount by counting bags, not measuring thickness. Read it on any bag. That is an FTC rule.And the borate is used in laundry products..
William the Geezer, the sequel to Billy the Kid - Shoe
so it is seeming like cellulose wins the popularity vote. one factor to mention about this house, in particular, is that there are no intake vents in the eaves. there actually are no eaves, as the gutter sits directly against the brick. there are plenty ridge vents on the roof, however. would this contribute to the general moisture in the attic from living space below? and would that influence the insulation decision?
thanks
Ridge venting only creates a negative pressure in the atic that sucks warm moist air up from the house into the attic thru any possible penetration. Lights, access panels, plates with driled holes for wireing......
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Ridge venting only creates a negative pressure in the atic that sucks warm moist air up from the house into the attic thru any possible penetration. Lights, access panels, plates with driled holes for wireing......
If all those "interior" penetrations are air-sealed first, then you will not be losing conditioned air ($$$) out the ridge vent. Then adding proper soffit vents will satisfy the local venting police.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
Neat quote box you have there.I don't know that you could ever do an adequate job of sealing all those on an existing house
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On an existing house it wouldn't be a "perfect" air tight seal. But it certainly can be more than adequate, especially with proper soffit and ridge vent openings. Then there would not be any major "suckage" on tiny penetrations from the top plates and/or interior ceiling plane. The flow would be easiest from the soffit up to the ridge vent.If you'd like the html code for the quote box, I can post it again. It's easy to do.Most web forums have built-in quote box capability, but not this one. I think a quote box helps to visually address who/what you are replying to in your own post.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
I'm fine with just using the keyboard to "...***..."Yes on what you said. I just thnk of the soffit venting to be first on the list though.
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>>Could be in San Juan where they don't bother with heating OR cooling. Or even windows you can close, for that matter.
Lost me with that one. My house appears to have windows, heat, etc. Looked over the fence and neighbor has same.
You live in Puerto Rico?
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
geographically challenged, are ya?
there's a San Juan on the west coast too.
There's a Saint John's River in Florida and in Maine too, but that has nothing to do with the context of the original example in the use of the phrase.
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The chopped FG is definitely cleaner!
You can get arguments both ways on what is greener.
in an attic situation - loose fill - the cellulose is slightly better performance.
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i've been around both fg and cellulose for many years. Blown in both. Used to prefer cellulose for friendliness factor. But always had some respiratory issues. (borates??) Have seen cellulose get very packed down after time, and especially after getting damp. Leads me to lean a little more towards fg now. Just seems more dependable in the long run, seeing how frequently moisture becomes an issue, at least here in great white north.
My son and I just finished blowing celulose in the attic and walls (mooney wall) in a small house. Having never done it before it was easy to do after a few visits to this forum. Be prepaired with a wrench and a shop vac to unplug the blower.
I calculated 45 bags for the attic for r38 and we ended up using 46. One day rental for every 20 bags. One problem at the orange box is they won't rent the blower without buying insulation. Seems that is the only tool in the rent store that you have to buy something to rent.
I think the total cost was about equal to the cost of bats and not sure about blown in FG.
I calculated 45 bags for the attic for r38
I am curious, why did you stop at just R38? Adding more cells to say R50 would have been cheap since you were already doing the job and had the blower. Minimum code of R38 is just that... a minimum. You could (should) go higher.
Being in North Texas you would get energy savings benefit both for heating in Winter and air conditioning in hot season.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
Actually in this city R30 is the minimum so we went for r40 12-13in. It's a small house with a 4/12 pitch roof and we were running out of space. From the drywall to the top of the ridge is only about 40 in. We had to leave sheets of drywall out just to poke the hose in the attic. We filled it to the top of the foam eve vents. Also had 1x3 strapping to cut the heat transfer to a minimum.
Finished getting the drywall up yesterday and we can cool the house with a 10,000 btu window AC unit on a 95 deg day.