What fasteners should I use?
My project is remodeling a garage into conditioned space. Part of the project is installing a 2×4 sleeper system over the existing slab and 6 mil plastic, installing 1 1/2″ rigid foam insulation between the sleepers and then covered by 3/4″ OSB. What fasteners should I be using to secure the OSB to the treated sleepers? What type of rigid foam will work best?
I'd use stainless ring shank 8# nails or if time is not a factor you could screw it down. I'd want something tougher than plastic though. I would think that a self-adhering membrane that would seal around nails would be more desirable but I know almost nothing about basements. I did find this, and several more, doing a quick search.
I've never used it but I think it would be time well spent to find out more.
To be clear, the 6 mil plastic goes down first, then the sleepers and rigid foam. I'll do the research you suggest.
You might consider a full layer of foam, topped by two layers of floor decking with staggered joints.
and links from there will inform you on the alternative.
I used this idea for my basement, with a few modifications: Dorkin Delta-FL under the foam to allow any vapor coming up from the slab to dry and slowly diffuse into the interior air. High compressive strength XPS foam and only 1 layer of OSB, attached with tapcons to the slab.
The setup is super strong. We have a full gym in the basement and I haven't detected any issues with spongy floors, squeaking, or denting due to point loads of my treadmill.
I agree with above: SS Ring Shank Nails. Use a coil gun if possible.
Is a coil gun preferable to a framing gun shooting 2" nails? 2" is the minimum my framing nailer can handle, which overlaps with longer roofing/siding nails