I've spent the last couple of hours on google reading about basement subfloors, with no definitive answers... so advice is needed!
Live in SE Michigan, I have a dry basement. I was going to put 1x2 pressure treated strips down, then a vapor barrier, then plywood. Is this the correct order, and do I need a vapor barrier?
2nd, what's the typical spread for the strips, 16" OC? If the strip go down before the vapor barrier, do I just need to glue them down? Should I insulate between the strips? TIA!
Yeah, I've seen those and related items, such as DriCORE. Really don't want to spend that kind of money, however.
2nd, if I did spring for that, I take it I can build right on top of it? How does that affect wall integrity and plumb when the floor is floating?
At a local Menard's big box store I saw an interesting product made just for this. They have 2'x2' squares of OSB looking boards with a heavy plastic waffle like design on the back. The plastic is the spacer for between the wood and the cement. Each panel also has the tongue and groove to interlock together. I imagine you would put construction adhesive to the cement fit and panel and repeat. The plastic may even do the vapor barrier too.
An issue is moisture. You dont want to do all that work and find years later it is molded, I just use foam carpet padding and carpet its the easiest way to insulate and have a warm floor, plus all basements are subject to the inevitable flood, your water heater will leak, pipes will break, the washer and hoses will go, you will never dry out the airspace or wood completely. Any leak from upstairs will ruin the subfloor.
There's no particular reason why the strips need to be fastened to the concrete at all. It's not like they're going to fall off, and once the plywood is attached to them, they won't be moving sideways, either. I'd put the vapor barrier down first, then the 1x2s, with 3/4" foamboard between them, then the plywood. the spacing depends on what you're using for plywood, and whether you're putting it down parallel to or perpendicular to the "joists" but 16" o.c. is normal.
I don't have any personal experience with this but I've read about it. I think that the vapor barrier is important, and that it goes against the concrete slab. There's no reason to let any moisture reach the sleepers (the 1x2 strips). Not sure if the sleepers need to be PT when you have a vapor barrier. Have you done a moisture test on your slab, where you tape some plastic down and check for condensation 24 hours later?
If you are going to use sleepers, then I would definitely insulate between them, with a rigid foam board product. That, in my mind, is the only reason to use sleepers, to provide extra height for insulation.
If you like the idea of a floating subfloor, you can make your own easily enough. Just put down the vapor barrier, and then use two layers of 3/8" or 1/2" CDX plywood. Use full sheets where possible, and run the two layers with the long dimensions perpendicular. Then screw the two layers together using short screws that won't hit the vapor barrier. If you do this, let me know if it works well, as I may be trying it myself soon.
If the basement is dry, vapor barrier isn't very important (except possibly with hardwood).
Secondly, especially if you're going to carpet, you don't need the new subfloor. Use a premium grade carpet padding.
One way of testing the floor is to place a 12" square piece of plastic on the concrete, and then seal the edges with tape (ie: plastic packing tape, not something porous like duct tape).
If after several days, you don't see condensation under the plastic, you don't need a vapor barrier.
I actually think that putting down a vapor barrier can be counter productive. It might be better to let the water vapor pass through rather than letting it condense under your floor. I had two floors in my basement, one had furring strips with a plastic barrier underneath. The other had carpeting. I had occasion to take up the floor with the barrier and it was a mess under there. I did test the floor with the carpeting and did get moisture trapped underneath the test area, but, as noted, never had a problem by letting it pass through on its own. MLD
Yes, but there was a downside. So much water gathered under there that it actually started to travel into an adjacent bathroom. I started to notice water on the floor in the bathroom cabinet and determined that it was coming from the adjacent bedroom closet. At times it came from under the cabinet into the bathroom. I've since tore up the floor, laid new plywood (on strips) without the plastic barrier and have not experience a similar happening. Cheers, MLD
The tile (vinyl or ceramic) probably really does need the wood subfloor.
Tile may come loose if you get a flood. If it's vinyl-self-stick, make that "WILL" not "may".
The other comment about not using vapor barrier underneath carpet makes considerable sense. If there is very mild condensation, not blanketting it with a impermeable membrane will allow the moisture to evaporate thru the carpet without doing any harm. But anything glue-down will likely have problems - ie: float off the concrete or rot the subfloor.
I have seen 60 yr old tile ceramic and vinyl type in countless old homes on concrete that have had water, even mine. They hold up fine to temporary flooding, that is why they are common, Im sure old glues were oil base
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