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Discussion Starter · #1 ·
Hi all,

I'm working on rebuilding a bathroom that was unfinished when we moved into our new house back in September. It previously had a disconnected clawfoot tub sitting on a subfloor. We're installing an alcove tub and shower, and tiling the back and side walls, as well as a bench (space filler) on the right side of the tub. The new plumbing and tub installation is being done professionally, and I'm doing the finishing work.

My question today is regarding proper insulation of the back exterior wall (photo below). As it is now, the exterior wall is covered in foil-faced board, unsure of the thickness, with spray foam filling any gaps. The lower ~17.5" will be covered by the bathtub, and the rest will be covered in backer board, waterproofed, and tiled. *There will also be a new vinyl window installed.

Before the tub is installed, I want to make sure I add any additional necessary insulation along the exterior wall, since I'll lose access to the lower tub area. From what I've been reading, I need to create an air barrier, and it also seems like fiberglass insulation is not recommended in the bathroom environment.

I was considering adding second layer of rigid foam insulation overtop of the preexisting foil-faced board, and then sealing gaps with more spray foam. I have about 1.5" thickness to work with. Would this be an acceptable approach? Is added insulation beyond what's already in place necessary at all?

Also worth noting that I'm in northern New Hampshire, so the winters are good and cold.

Many thanks for your input!


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