Rigid foam sandwiched in wood subfloor?
![](https://secure.gravatar.com/avatar/dec3d8e9592704a7790c99b1b20001f9?s=52&d=https%3A%2F%2Fimages.greenbuildingadvisor.com%2Fapp%2Favatars%2F200x200%2Fs.png&r=g)
Hi,
I’m re-doing my living room floor.
When I strip it down to the T&G subfloor, I will have about 1″ to make up, since it will be lower than the kitchen floor it butts up against.
Below is an unfinished. basement.
Originally I was going to do OSB as a base with a layer of thinner plywood to get up to the proper height. But I have seen a lot of people doing rigid foam in their basement floors – Foam, then ply or OSB, with flooring on top.
Can I do this here, to get a little extra insulation between my living room and the basement? I was thinking 3/8 or 1/2 rigid foam, followed by 5/8 or 1/2 plywood.
Is this acceptable? Is there a reason foam would be OK over a slab, but not over a T&G subfloor?
Thanks for any help! And let me know if you need to know more
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
![](https://www.greenbuildingadvisor.com/app/themes/greenbuildingadvisor/dist/img/modules/detail-library/thumb1.png)
![](https://www.greenbuildingadvisor.com/app/themes/greenbuildingadvisor/dist/img/modules/detail-library/thumb2.png)
Replies
Sean,
Yes, you can do that.
It's even possible to leave the 1-inch height difference between rooms, and to simply make a custom tapered threshold at the doorway. Of course, some homeowners hate that idea; others don't mind. Such tapered thresholds are common in older homes, where flooring is replaced in one room at a time, on different schedules.