Shop Remodel Question of the week #4 - Insulating Concrete Floor

[Joe Cowan]

I am starting my floor project next week. I posted the same question a couple of months ago and am tentatively planning on doing it this way. Vapor barrier, 2x4 dry PT 2x4's on 16" centers, but the 2x4's will be cut no longer than 3' and positioned so that the butt joints are not opposite one another and allowed to "float" (no tapcons"). The guy that recommended this said he was advised by professional gym flooring installers to do it this way. I will cut some 1/2" ply up into 3 1/2" strips and place that on top of the 2x4's to make the depth 2" and then place the rigid foam in between the 2X4's. Then the 3/4" subfloor and last a utility grade hickory 3/4" floor from Lumber Liquidators. I have the wires coiled up against my shop wall to run under the floor for my Table saw (220 volt) and also for a 110 outlet. Unless I change my mind (I may just put 1" foam down and not build up the 2x4's to 2" think) this is it.

[Gerry Grzadzinski]

Why not just use 1-1/2" foam with the 2x4's?

[Joe Cowan]

Why not just use 1-1/2" foam with the 2x4's?

I have not been able to find it locally. That is what I would probably do if available. Buying 1/2" and 1" to make the 1 1/2 piece is more expensive than the 2" one piece unit is. But I could do that and save having to cut and install the 1/2" ply on top of the sleepers.

[Jim Terrill]

I have not been able to find it locally. That is what I would probably do if available. Buying 1/2" and 1" to make the 1 1/2 piece is more expensive than the 2" one piece unit is. But I could do that and save having to cut and install the 1/2" ply on top of the sleepers.

Where are you looking? They don't sell it at the BORG here, but if I go to a quality lumber yard, I can get 1/2" to 2" in 1/2" increments as plain foam or foil faced (which I recommend). Granted this is the north and we are all about insulation, but you should be able to find it.

[Joe Cowan]

I was going to use the blue foam type insulation. Lowes carries the foil backed insulation in the 2" material, that is the most expensive. With the plastic down, I did not think I needed the foil backed insulation.

[Jim Terrill]

I was going to use the blue foam type insulation. Lowes carries the foil backed insulation in the 2" material, that is the most expensive. With the plastic down, I did not think I needed the foil backed insulation.

It adds another few Rs to the insulation. Up to you whether or not it is worth the extra cost, the key when using the rigid foam though is to use the foil tape to prevent air movement.

[Joe A Faulkner]

Joe, please post some pictures as you make progress on your floor system. It sounds like you are forming up a torsion box. I am interested in seeing your frame before you apply the subfloor. I am also interested to hear about your experience with the utility hickory floor. At 89 cents a sq. ft. I'm tempted.

[Rob Fisher]

Joe, please post some pictures as you make progress on your floor system. It sounds like you are forming up a torsion box. I am interested in seeing your frame before you apply the subfloor. I am also interested to hear about your experience with the utility hickory floor. At 89 cents a sq. ft. I'm tempted.

Joe,

I if I understand Joe C. correctly he is just doing a floating floor, no torsion box. The 2x sleepers are dry laid (no tapcons, no glue), and staggered. Then the subfloor is attached overtop as normal. The only thing different is that the line of attachment points will stagger. Meaning when you look at the installed subfloor, the screws (or nails) that attach it to the 2x sleepers will not be in a straight line. They will stagger with the sleepers below. Dry laying the sleepers allows them to expand and contract due to thermal or moisture change (hopefully just thermal), therefore not affecting the subfloor or finished floor above. Hope this makes sense.

Also if there is a vapor barrier installed between the concrete and the sleepers then the foil facing on the insulation is useless.

Rob

[James Stokes]

Here is what I did in my house, it could be done in the shop just as easy.I installed 3/4 t&g blue foam on my floor then installed a laminate floor over it.

[Joe Cowan]

Joe, please post some pictures as you make progress on your floor system. It sounds like you are forming up a torsion box. I am interested in seeing your frame before you apply the subfloor. I am also interested to hear about your experience with the utility hickory floor. At 89 cents a sq. ft. I'm tempted.

I am not making a frame. I will be laying down the 3' pieces of 2x4's in a line, then laying down a row of insulation, followed by another row of 2x4's and so on. The weight of the 3/4 ply and the hickory will be what holds the floor down. Also, I am the landlord for a Lumber Liquidators store. The manager told me the hickory was good stuff. I will ask him again before I order but am leaning toward the hickory.

[Joe A Faulkner]

Now I understand; I'm curious about the decision to cut the 2x4's into 3' pieces; you mentioned a gym floor installer recommended this? What was the explanation? Does cutting these into shorter lengths serve to reduce warping?