SPRAY FOAM INSULATION

We gave a lot of thought to the insulation we should use in this house and in the end, decided on a hybrid system.  The roof has 1 1/2" of rigid foam above the plywood roof deck, then about 1 1/2" of spray foam just below deck and finally R30 fiberglass batts.  Each component has it's own role to play.  The rigid foam keeps the plywood somewhat warm, to prevent condensation, the spray foam air-seals the house and the fiberglass batts are still the most cost-effective way to build up R-value.  All together, along with the roof system, it should give us about R50.

The walls are arund R20-25, with 1 1/2" of spray foam and R15 fiberglass.  Except for where they're clear, of course!  Each layer of polycarbonate is about R1.6, so even with two layers and a dead air space in between, we'll be lucky to get R5.  Still, that's better than any window I've ever specified.  

Here, the spray foam guys look like they're being very neat, and they were for the first two days.

Then, the end of the week crept up on them and suddenly they had a lot to accomplish on Friday.  No one likes to stay late on Friday.  I'm not sure exactly what they did - maybe opened the sprayer up a little more - but they sprayed more foam on Friday afternoon than they had in two previous days combined.

Until the gun blew up.  It's hard to really hear a scream through a respirator, over the job-site radio and the other power tools.  Luckily, no one was injured, and the mess was surprisingly contained.  Most of it wound up on that sheet of plastic.  

All in all, I'm glad we did the foam.  I believe it adds rigidity to the structure, provides a fantastic air seal and a lot of R-value per inch.  The sales pitch was grossly exaggerated, but they always are.  You're basically paying for material on the wall, so get a bid and a good measuring stick to check their work.

And, right after the spray foam, we did fiberglass batts, a much more tidy process, I might add.

The Knauf Ecobat, formaldehyde-free, yadayadayada

See how neat these guys are?  They even cleaned up after themselves.  Not like some other spray-foam contractors I know.