MCHammer

Is there really a noticeable difference?

Just bought a new home and the builder is charging an upgrade to go from R25 to R40 spray insulation in the garage.

It'll be my son's room (above the garage), so i just wanna know if it'll make a noticeable difference.

Thank you.

AtticCare

leave it, your garage shouldn't get to the extreme temperatures, and this is the floor of a bedroom you are talking about right?

kok328

In most cases, the garage WILL see extreme tempatures both in summer and winter however, R25 should be adequate insulation.

kelargo

what kind of foam is getting installed?
the difference in R value would be the thickness of foam applied.
make sure it is closed cell foam. open cell acts like a sponge.
One vendor's foam I've been using claims to be R7 per inch of thickness.

GBR

Kwik Build Panels - Insulation facts and misconceptions article

Gary

Perry525

The operative will spray by hand, he will guess how much foam he is depositing as he goes. If they are trying to make money, he will probably not spray it on to the correct depth, working on the assumption that no one will ever know.
Get a specification in writing, confirming exactly what you are getting for your money, stand there and watch him do it.

Note: spray foam will shrink by 15% over time!
About 15 years, confirm that the specification is for then, or now!
Where it does shrink back, you will have a cold patch/patches, which will be subject to condensation/damp and possibly mold in time.