I was in an attic yesterday that had the spray foam insulation and I was amazed how cool the attic was considering it was 4pm in Houston.

My question is, would it be worth having it done on my 1 story house, built in 2001, single pane windows, blown in insulation, brand new roof with tons of ridge vents.

This is just an idea at this point, as I don't even know what it costs to have done

A big plus is the fact that it seals better than traditional insulation. That allows your vents and soffets to operate properly and keep your AC'd air where it's supposed to be. Not sure if it's worth it for your situation, but that stuff is crazy good.

That was the impression I got yesterday.

Our house is 2500sqft, detached garage, would love to do it too but feel like that might really jack up the price

It is good if you are building the house, putting it in is worth it.

Retrofitting it can be hard and not really work as well. Cost might not be worth it.

I had it on my old house (as it was a new build) and was awesome. The hottest my attic got in the summer was about 95F.

~egon

I am always a little hesitant about retrofitting with foam. House built that way are amazing in the attic.

It has a pretty big effect on the HVAC design. I have inspected houses that ended up having way way oversized AC units because they changed to foam. That leads to humidity issues, short cycling, etc.

Also not sure about the ROI time, since it obviously isn't cheap.

I put spray foam in the attic in my new home build in 2013. The walls are 2x6 with blown-in blanket. My roof is tile. We have no significant shade in our yard and live on the top of the tallest hill in town.

It wasn't an inexpensive upgrade and I have no idea what my ROI is.

What I do know is that my winter electric bill is around $75 and the highest my summer bill has been is $200. I have 3000 sqft with two heat pumps (one for the upstairs game room) all electric. My attic space never gets above about 80 degrees. We run an Ecobee and keep the downstairs at 74 and upstairs at 80 (unless we're up there...which is not often).

I also know that I'll have spray foam and/or BIB in any house I own in the future.

Im a big fan if it is a new build and designed with the foam in mind.

JonMan

We did it as a retrofit and i would say after 4 years we got our money back. Hell, after the first week we had it down it made our temperature difference between 1st and 2nd floor only 2-3 degrees. Before it was 7-8 degrees so I'm happy with it.

Was busy today but talked to a friend who's family is involved in different aspect of home building

He talked to their insulation contractor and he said 100% worth doing on new build. Retrofitting can be trouble some because as other have said, the home wasn't designed for it and nothing is supposed to exhaust through it so things might have to be reworked.

I didn't ask if that meant just the obvious like hot water heater or included even a bathroom exhaust.

Sounds like the cost might not be worth it