I have some friends that are building a house and they have the option to do spray foam insulation in for an additional $3,000 (~2,000 sf house). Is it worth it at that price for that size of house?

I just realized that I don't know if this is attic only or everywhere, I will have to find out.

We're building new and decided to do foam. I don't think you can do it only in attic...I understood it had to be all or nothing.

Not an expert but my current research suggests foam is a good option in new construction BUT, it has to be done right. Also better for places with lower humidity.

I'm trying to improve an older house and decided to go with blown in cellulose.
There are also two kinds of foam-open cell or closed cell (I think) can't remember when which one is better.

I would say yes.

Another thing to consider is that foam should block air movement and small critters. That will increase R value of insulation.

~egon

Also, the R-value for foam is 3X that of regular insulation so it's great for walls, etc...Twice the insulation!!!

Quote:

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The R-value of spray foam insulation is approximately 6 per inch so those using spray foam as their insulator will need about 6.3 inches of thickness to reach R-38. The R-value of fiberglass insulation is approximately 2.2 per inch so much thicker fiberglass insulation is required to achieve the same R-value of 38.

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Closed cell is better than open cell foam...

Quote:

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Open-cell spray foam has an R-value of about R-3.7 per inch, while closed-cell spray foam has an R-value that may be as high as R-6.5 per inch.

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When I renovated our current home, I had gutted all the exterior walls to the studs and used closed cell spray foam from Foam-It-Green and couldn't be happier. Great stuff and I can really tell the difference.

I even used it on the attic floor over the main living area and the master bedroom. There;s a significant difference in those rooms versus the other rooms that only have cellulose insulation in the attic areas.

And no drafts around the windows and wall outlets like before! Stuff also add structural integrity to the walls and ceilings...I know as I had to remove about a 4 sq ft of it from the attic ceiling as I decided to revise my room layout a little bit and that stuff was a b'tch to remove!

Foam. It's not really a question if it's an option between the two.

The real questions start on building a proper envelope, proper application and diminishing returns.

Gary79Ag..... the comment that closed cell is better than open cell is not necessarily true as a blanket statement. They have their different uses based on structures.

Foam attic, spider walls.

We've looked at it for a house we are renovating and while it does perform better when it comes to R-value, it's not nearly as good at sound deadening/insulation.

Also, make sure the HVAC system is updated to account for spray foam. I've read a number of stories where folks use sprayfoam but size their AC based on regular fiberglass. The house cools down a lot quicker because the AC is bigger than it needs to be. This leads to less reduction of humidity in the house and eventually mold. It's an easy problem to solve, but often overlooked.

Rather than start a new thread, I figured I could add-on a question here.

I have a 1949 craftsman home that has a blend of possibly loose-fill recycle (like GreenFiber) + white cotton/fiber glass loose blown: NO rolls of fiberglass. The white stuff doesn't itch or scratch at all which I find confusing, and it feels more like cotton than a fiberglass.

Anyway, I was going to add additional loose insulation.

Curious if anyone knew the difference between GreenFiber 541LD and 765LD. Also, having added some 541LD before by hand, I can already argue the "low-dust" is a bit of a joke...

https://www.homedepot.com/p/Greenfiber-Low-Dust-Cellulose-Blown-In-Insulation-19-lbs-INS541LD/100318635
https://www.homedepot.com/p/Greenfiber-All-Borate-Cellulose-Blown-in-Insulation-30-lbs-INS765LD-E/300583399