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susan cosentini Posted: Jun 21, 2011 02:11 PM	deep energy retrofits what is 1# foam? is there such a thing? what is the R value? can it be injected into stud cavities of existing homes without removing siding? thanks
mason Posted: Jun 21, 2011 02:54 PM	l lb density foam does exist. At least 3 companies manufacture it. It has a compressive strength around 10 psi and an R value that is around 4-5 per inch depending on the formula. the problem with any polyurethane foam cavity fill insulation is that the foam expands, creates pressure and can blow out the drywall. This can happen even with a low density product unless it is specially designed for that purpose. You can fill an empty cavity by using a froth injection foam. In this situation, there is an additional blowing agent stream added to the B side using a small proportioner that is attached to the main proportioner. The 3rd stream, pre-expands the foam and reduces the temperature pressure so that it does not blow out the walls. I used this type of equipment and foam in the 70s and 80s, but don't know if anyone is making it now or what the blowing agent is that they would use. Back then we used CFC 22 as the 2nd blowing agent in the 3rd stream. You might contact some of the major foam manufacturers for help. Another problem in existing walls is what to do with the fiberglass already in it. The foam would need to have enough pressure developed to move the fiberglass over without busting the drywall out. We were never successful in accomplishing this with the foam we injected in the 70s and 80s. I am skeptical the newer foams can accomplish it, although I have seen advertisements to the contrary. As always, I am open to consider any qualified evidence that the injection foams can completely fill a fiberglass filled wall cavity. Photos, before and after, infra-red camera evidence etc. would suffice.

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Comments

susan cosentini

Posted: Jun 21, 2011 02:11 PM

deep energy retrofits

what is 1# foam? is there such a thing? what is the R value? can it be injected into stud cavities of existing homes without removing siding? thanks

mason

Posted: Jun 21, 2011 02:54 PM

l lb density foam does exist. At least 3 companies manufacture it. It has a compressive strength around 10 psi and an R value that is around 4-5 per inch depending on the formula.

the problem with any polyurethane foam cavity fill insulation is that the foam expands, creates pressure and can blow out the drywall. This can happen even with a low density product unless it is specially designed for that purpose.

You can fill an empty cavity by using a froth injection foam. In this situation, there is an additional blowing agent stream added to the B side using a small proportioner that is attached to the main proportioner. The 3rd stream, pre-expands the foam and reduces the temperature pressure so that it does not blow out the walls.

I used this type of equipment and foam in the 70s and 80s, but don't know if anyone is making it now or what the blowing agent is that they would use. Back then we used CFC 22 as the 2nd blowing agent in the 3rd stream.

You might contact some of the major foam manufacturers for help.

Another problem in existing walls is what to do with the fiberglass already in it. The foam would need to have enough pressure developed to move the fiberglass over without busting the drywall out. We were never successful in accomplishing this with the foam we injected in the 70s and 80s. I am skeptical the newer foams can accomplish it, although I have seen advertisements to the contrary.

As always, I am open to consider any qualified evidence that the injection foams can completely fill a fiberglass filled wall cavity. Photos, before and after, infra-red camera evidence etc. would suffice.

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