subfloor/sleeper assembly over slab
I have a new addition in western Washington, built over the slab that we poured, rather than digging a crawl space. The exterior walls are on a short perimeter foundation, and the slab is isolated from the walls by 2″ foam. The slab has a continuous vapor barrier below, and drainage is provided outside the perimeter foundation.
So far the slab is staying perfectly dry and warm through our wet and cold winter. But I want to install a wood subfloor for comfort. Initially I thought I would put down 2×2 sleepers directly down on the slab, with foam insulation between them. Now I’m reconsidering, trying to come up with an assembly that would offer more “cush” as well as sound insulation.
Does anyone have any recommendations for a good assembly? The subfloor will remain exposed for some time, while we save up for floor finishing, so I’ve ruled out homosote over the subfloor, but was toying with installing it below 1″ sleepers. But I’m nervous about it being in contact with the slab, even though it is currently dry. Any experience or inspiration?
Replies
I would opt for 2X4 sleepers rather than 2X2. Less likely to split out when attaching to the concrete slab. I think with the set-up you just described..sleepers, foam insulation, plywood subfloor on top...you will have plenty of cushion and sound dampening underfoot.
I would use either kiln dried, PT 2x4s (my first choice)...or I'd use regular 2x4s and place a strip of 30# felt underneath each one. I'd mechanically fasten each sleeper, either with tapcons or PAT fasteners.
I did a floor overtop a concrete poured slab on a second story industrial building. We used regular 2X4s ( dampness not an issue here) and shot them down with PAT's. We insulated with foam in between, and laid down a 3/4 subfloor..glued and screwed. Later we installed 1/4 luan over top and installed vinyl floor tile. That was approx 12 years ago. Floor is as good today as when first installed.
Davo