Sub Floor question

[SteveC]

I am putting a basement apartment in my house. Putting down a subfloor, 2x3 strapping with 1" styrofoam covered with 5/8 T&G Plywood, strapping on 16" Centers.

What would be the best to fasten the strapping to the concrete? Was thinking first a bead of PL400 adesive glue and then renting a hilti powder Actuated gun to put a couple of concrete nails in each 8 foot length.

Is this overkill?

I have a air powered framing nailer, would that drive the nails into the concrete?

Any insight would be appreciated.

Thanks, Steve

[Robert Allison]

The PL400 is the perfect tool for the job. You might buy some tapcons and shims in case you have a low spot or need to mechanically fasten the sleepers (the correct term for what you are calling strapping). I once saw a detail for this method that described laying the sleepers "in a river" of PL400. I like that term. It describes how I do it. Get the larger tubes and a large caulk gun.

[gfretwell]

I agree with Robert on the PL400, just be sure your code does not require PT lumber for that. In Florida all lumber in contact with concrete must be PT. I am not sure what other areas require but it does make good sense to do it.

[SteveC]

Not required here in Newfoundland. Thanks.

[SteveC]

"Robert Allison" wrote

Thanks for the tips. I'm gonna go with PL 400, then concrete nails if needed . Thanks.

[EXT]

I have done the exact same thing in my basement about 20 years ago. Used cedar sleepers and ram-setted a few nails into the glued down sleepers. You will need a variety of materials, shims for low spots, a planer to lower high spots as concrete floors are anything but level and flat, use glue to bond the sleepers but be sure to use Tapcon or power nailing to keep the ends of the wood from lifting and/or warping.

It is important to keep a couple of inches clear from the walls to allow any moisture a place to go, then leave a few channels, to the drains or sump, clear of wood and foam so that any moisture that gets through the walls or floor can drain away and not be trapped under the floor.

[S. Barker]

I don't see a need to fasten it at all unless it's just to keep it in line before the plywood goes on.

s

[S. Barker]

that's the rule everywhere. It's in the IRC.

s

[EXT]

Be sure to fasten it, your 2x4s can warp and curl uncontrolled when in contact with the concrete and house air. Pound them down and lock them in place or your floor will be a bumpy mess.