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Foam vs Cellulose Insulation

03-01-2010, 04:07 PM
Post: #1
Foam vs Cellulose Insulation
Should you use foam (either rigid board or spray-in) to insulate a green building? In my 20+ years in the green design/build field I have used plenty of foam to insulate the foundations of buildings. I have also used quite a lot of spray foam to insulate above grade walls and ceilings. But I have always felt uneasy about the high-embodied-energy, petro-chemical ingredients, off-gassing, and general nastiness of foam in all its forms.

I still believe that we need to use rigid foam board (and lots of it) to properly insulate our buildings below grade. There just isn't any other way and the potential energy wasted due to heat loss to the ground is worse than the potential environmental hazards of the foam itself.

So I've come to accept the necessity of foam for below grade installations. However I'm less and less accepting of the need for foam above grade. For every situation where an argument can be made for using foam (such as in a cathedral ceiling, or as a continuous exterior insulation layer to bridge thermal breaks) I believe there is a better argument to be made for designing structures that don't need foam.

Passive House advocates have developed excellent methods of creating very high R-value wall assemblies without using foam. I think there's a really good lesson here. Sure we may need to build thicker walls and roofs to get the same R-value, but cellulose is SO much better for the environment than foam I think it's worth it.

I expect I'll continue to use foam (especially below grade or in existing buildings where the design options are limited) but I'm going to try to reduce the need for it at every opportunity.
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03-01-2010, 05:04 PM
Post: #2
RE: Foam vs Cellulose Insulation
Andy,

Have you ever seen research testing the VOC levels in a home after the insulation of foam?
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03-02-2010, 08:01 AM
Post: #3
RE: Foam vs Cellulose Insulation
Great question, and I haven't tested VOC levels after insulating with spray foam.

To be honest I have no idea what's involved in testing VOC levels. Wouldn't you need to test for the specific chemicals that might be offgassed by the foam?
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04-14-2010, 03:23 PM
Post: #4
RE: Foam vs Cellulose Insulation
(03-01-2010 04:07 PM)andylemann Wrote:  Should you use foam (either rigid board or spray-in) to insulate a green building? In my 20+ years in the green design/build field I have used plenty of foam to insulate the foundations of buildings. I have also used quite a lot of spray foam to insulate above grade walls and ceilings. But I have always felt uneasy about the high-embodied-energy, petro-chemical ingredients, off-gassing, and general nastiness of foam in all its forms.

I still believe that we need to use rigid foam board (and lots of it) to properly insulate our buildings below grade. There just isn't any other way and the potential energy wasted due to heat loss to the ground is worse than the potential environmental hazards of the foam itself.

So I've come to accept the necessity of foam for below grade installations. However I'm less and less accepting of the need for foam above grade. For every situation where an argument can be made for using foam (such as in a cathedral ceiling, or as a continuous exterior insulation layer to bridge thermal breaks) I believe there is a better argument to be made for designing structures that don't need foam.

Passive House advocates have developed excellent methods of creating very high R-value wall assemblies without using foam. I think there's a really good lesson here. Sure we may need to build thicker walls and roofs to get the same R-value, but cellulose is SO much better for the environment than foam I think it's worth it.

I expect I'll continue to use foam (especially below grade or in existing buildings where the design options are limited) but I'm going to try to reduce the need for it at every opportunity.


I still haven't seen a better product for insulating cathedral ceilings or rim-joists than a good closed-cell 2 part spray foam. The only other way to insulate a cathedral ceiling is to install baffles from the eaves to ridge to maintain appropriate ventilation. This isn't necessary with spray foam because the foam acts as an air barrier as well, and there are no longer exposed sections of roof decking on which condensation can form.

I guess that you need to compare the embedded energy and petro-chemical use to the fuel that will likely be saved over the lifetime of the building.

As for VOC's....well, that's a different story, but a high-quality UV catalytic filter on the furnace should be a significant help with that issue.
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07-30-2010, 02:23 AM
Post: #5
RE: Foam vs Cellulose Insulation
Well I have just read this all information and I can say stuff. But I have just heard that Fiberglass-based blow-in insulation is a popular choice for attics and hard to reach areas. Properly applied, blown-in fiberglass insulates well.

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09-08-2010, 12:51 AM
Post: #6
RE: Foam vs Cellulose Insulation
well i am new in this forum and its good to see the cellulose insulation because we should clean our atmosphere and environment by solving waste disposal problems also controlling air pollution by using this kind of materials.

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10-24-2010, 03:52 AM
Post: #7
RE: Foam vs Cellulose Insulation
Yes I agree with you and did you know that cellulose insulation is sprayed it ensures that there is no sagging or drooping like that in fiberglass batts. Complete coverage will mean that heat and air are not flowing from room to room. This will also be a precaution from any potential fires in the house.

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