yes! batt insulation is one of the worst modern ways to insulate your walls and roof. even if installed perfectly correct (hardly ever is) it does not slow air infiltration much. Spray foam is a very dense closed or open cell foam that allows extreme minimal air and moisture to pass through. by first spray, they effectively sealed all holes, cracks, and possible ways for air infiltration due to its expanding qualities. by adding additional cellulose mass, which is a very good insulating product, creates a higher thermal barrier. Cellulose can stop air movement if thick enough, however it sounds like he did it correctly.

For sure! We spray foamed our basement and it is so warm and not drafty! It's for sure the way to go.

Spray foam roofing offers the highest R-value of any traditional roofing insulation, leading to decreased energy consumption.� Spray foam roofing is a rigid, closed-cell plastic created by a combination of two liquid components, which react in seconds and can be walked on in a matter of minutes. This roof system insulates and creates a lightweight, seamless, waterproof blanket over the substrate.

Here is a link that might be useful: spray foam insulation

oh, my yes! best thing goin', tho' certainly not cheap. that and lining/sealing the crawl space of our house has made a huge difference.

Not that I mean to be a fearmonger - that's not my way - but I'm still cautious about this.

I remember all too well the stories of homeowners installing urea formaldehyde foam insulation 35-40 years ago. It was billed as the perfect insulation, and then the other shoe fell. A few years later, these same folks were facing huge bills to have their foam insulation removed, when it turned out that its formaldehyde emissions were making them sick.

Going even further back, we now know the asbestos hazards associated with vermiculite insulation. I shudder when I remember shoving that stuff around in attic floor joists with my bare hands many, many years ago. I wasn't wearing any kind of dust mask, because who knew? Not I. But when it was installed, that stuff was the latest miracle product too.

I would hate to install this latest miracle in my house, and learn 10 years from now that some incurable illness I'd developed had been caused by it. Already I'm reading that, like many other modern synthetic homebuilding materials, some kinds of urethane foam insulation can release poisonous gas (in this case, hydrogen cyanide) in home fires.

Maybe in another decade, I'll adopt foam. For the present I'm sticking with what I know - good old fiberglass batts.

A lot of folks on this board slam it, but fiberglass has a long track record of safety (as long as you're careful when installing it), and decent effectiveness when applied correctly. True, you can't use fiberglass to close off air infiltration, but IMO that's not what insulation is for. The proper material for that purpose is caulking compound.

Got to completely agree with Davidr. Spray foam just doesn't have the track record, fiber glass and caulk do. Seems to be a certain amount of variability in final composition of foam due to site mixing that can be problematic. Cellulose insulation still doesn't have a long enough track record either.