We're building the house ourselves so this is a multi-year project. Early in our build we had 3 installers over once framing was up (before mechanicals were in) to get estimates on the spray foam insulation (we were not ready to install but needed to know for budgeting). Two installers quoted poly and one installer quoted soy. The soy installer said he also used poly but the pricing on the soy insulation at the time was better so he was using that more often.

About a year later we called back the installers to review the job and update the quotes. The installer that originally quoted soy came to quote and told us he was quoting poly and no long installing soy. He told us he had a major problem with shrinkage at a customer's home. A customer had called about 6 months after installation and said he had a problem and wanted to meet with him. The installer met with the homeowners and could immediately see the damage to the ceiling. The soy insulation sucked in the drywall on the ceiling so that you could see the wavyness of where the joists were and where the drywall had been sucked in. The drywall sheets sucked in so much that the drywall had actually seperated at the seams. He did a check of the attic and insulation and agreed with the owner that the problem was the soy. He contacted the soy company to have them investigate. The soy company refused to admit the product was defective and refuse to pay to fix it (remove insulation, remove drywall, re-drywall, re-paint, re-insulate). The installer ended up paying to fix the damages himself. Though he installed soy insulation for many customers he only had one customer complaint but he stopped selling the soy because the soy company did not stand behind their product.

When he told me this I too looked online for information on soy insulation shrinkage problems but couldn't find anything. We had three installers bid the final job (all bid poly) and his (originally the soy installer) pricing was the best. I have nothing written to refer you to just passing along what I was told.

I am never an "early-adopter" of anything. Especially not anything this critical to the performance of your house. $500. is small potatoes in the overall scheme of things. We're sticking with Icynene because it has been around for so long and is well proven, the bugs are out (assuming it's installed correctly), and the manufacturer has deep pockets, in case anything goes wrong.

soy, poly? What re you comparing; it's all low-density polyurethane foam isn't it?

Good point mightyanvil! All our quotes and our installation was for high-density spray foam.

Actually, I mispoke (typed). It is the icynene and you are right, the $500 dollar diff. is not a lot considering the total cost of the insulation anyway. I was getting the cases of "well, that is only ___ extra" and we're barely getting dried in.

I am worried about the shrikage issue and I have a very cut up roof with lots of valleys and gables so lots of places for initial leaks. Thanks for the helpful information. The only stuff I found were the "studies" done by the Icynene company.