Replacing squeaky subfloor over concrete

wizardofza

Hi everyone! First time poster here I think this is the right forum for this...

We have a spare front indoor room that the POs added, where an outdoor patio originally existed. It's installed over a concrete slab. There's no room above it - it's only one floor.

The wife and I want to completely overhaul the room. The biggest concern is the subfloor. It squeaks and heaves in certain areas when walked on. I took a peek under the carpet and they only nailed the subfloor to what I believe are sleepers. Needless to say, the nails aren't cutting it.

I also don't think there's insulation under the subfloor because between the joints of the plywood you can just feel the cold air coming up. And living in Buffalo, it can get cold here in the winter.

As the first step of the remodel of this room I want to redo the subfloor. What I'm planning on doing is ripping the entire floor out and replacing the sleepers with PT 2x4s 12" OC and then putting 3/4" tongue in groove on top of that.

What type of vapor barrier would be good to use in this type of application? What type of insulation would be good to use in between the sleepers?

OR, can I just get away with using 2" foamboard and putting the sub-floor directly on that using masonry screws to secure it to the slab (ala Holmes on Holmes)? Or is this just good for below-grade slabs (i.e: basement redos)?

Thanks for the suggestions!

AtlanticWBConst.

If the foundation of that room "is" the old patio, then be prepared for issues. Read on.

There may not be insulation there, there may also be inadequate insulation (not enough) -installed. There may also be openings/gaps somewhere, that is allowing air to draft in from the outside.

I started out saying that "if" the foundation of that room "is" the "old patio": then be prepared for issues. Such a "foundation" (and I use that term loosely in this context) may only be several inches in depth. As such, anything attached to it, would be subject to frost heaves, expansion/contractions, etc (in other words = seasonal movement).
Be prepared for continued squeaks and floor material flexing.

In NY, a proper living space should be built on top of 4' deep frost walls.

If you plan on going forward with the project: Use PT sleepers attached with treated or galvanized fasteners. Glue the 3/4" T&G down to the sleepers and use screws to secure. Make sure that you use the proper "treated", stainless, or galvanized - screws/nails for the PT - as the ACQ treatment in PT will corrode standard "bright" fasteners/nails.

Install a poly vapor barrier over the PT and the insulation (between the 3/4" T&G and the PT sleepers).

Alternately, you could install a layer of Ice & Water shield directly over the concrete slab, and attach all other materials over that.

Ridgid Foam Board

You should use the maximum amount of foam for the space's thickness. There is no need to use screws to attach it. You could simply place it onto the concrete.
Alternatively, I would suggest using a basic adhesive, and spray foam (canned) insulation around the edges - to create completely sealed areas.

Lastly: Make sure that the PT sleepers and the 3/4" PT subfloor are fully dried out (ACQ treatment fully cured), before you attach anything else to it.
ACQ PT shrinks over time, as the ACQ treatment cures & dries out.

Realize that the area may never be completely movement free.

__________________
- Build Well -

wizardofza

Oops. I meant to say, instead of using sleepers can I just get away with placing rigid foam board right on the slab, then the subfloor on that, and using masonry screws to screw both the sub-floor and RFB to the slab?

I've seen this on Holmes on Holmes, but only in sub-grade basement redos, never a room like this at grade.

Would this be a proper application? Would I still need a vapor barrier or is the RFB alone sufficient? Or do I scrap this entirely and just stick using sleepers with the RFB in between them?

Thanks for suggestions Atlantic, much appreciated.

AtlanticWBConst.

No, I would not recommend this. The foam is not a structural (Weight bearing) material.

= No Comment (Biting my tongue).

No.

Add the vapor barrier to protect the finish floor materials from even the slightest amount of vaporized moisture.

Install the ridgid foam between the sleeper bays. Seal with canned spray foam. Include a VB.


UR Welcome.

__________________
- Build Well -

jlhaslip

If you have the space (height) consider laying the 2 x 4 sleepers as per above (insulating between) with a second set of sleeper material laid in the opposite direction with another layer of rigid to suit the thickness of the second layer of sleepers. This will help by reducing the thermal bridging of the cold concrete up to the subfloor.

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wizardofza

How should I orient the sleepers? Should they be attached to the slab wider side down or narrow side down? Does it even matter? Seems that it would be easier to fasten them to the slab if they were wider side down.

I'm assuming I can get the foam board at widths to match either orientation? I just don't see them at Home Depot or Lowes. Maybe a building supplier?

Also, the sleepers on the second layer would run perpendicular to the sleepers attached to the slab?

wizardofza

Bump..

Anyone have any thoughts on stacking rigid foam board to meet floor of adjacent room?

Ron6519

If you want the floor levels to match, frame the patio area with whatever size floor joists you need. Patio floors are usually sloped away from the house, so you will probably need to either shim the framing or cut it to match the slope of the floor.
Whatever insulation you put in the bays will probably need to be cut to fit.
Ron