Basement Sub-Floor Using Sleepers - Need Some Pointers

[dave1949]

I usually find I have not done enough research on these types of projects. I would hate to see you do that work and buy the materials if it fails later. Not to offend, but I think you may be covering up an issue and hoping for the best.

One problem is the sleeper nails will all be penetrations of the vapor barrier. Another is you will probably have quite a bit of humidity fluctuation that isn't friendly to wood flooring. You could see cupping of the boards.

There is a lot of info out there, other people have confronted the same problems. It's just a matter of getting the right advice. You might try help boards operated by someone like Quikcrete or similar where you can post your situation and ask for recommendations. You never know what gems may be be uncovered. These folks are well regarded: Products You might ask about membranes that a floor "floats" on too rather than the nailing sleepers approach.

I would +1 the tile idea. But you still need to clean, bond, level, and maybe seal, the existing floor. Ceramic tile itself will take saturating conditions. The thin-set mortar used to bed the tile could be outdoor/exterior rated which ought to be moisture tolerant after curing like concrete. I think tile done right is your best chance of avoiding problems later.

 

[CHDinCT]

The pourable floor leveler is some pretty neat stuff. I have used it and have watched "pros" use it. Personally I would rather pour than shim, and do tile afterwards. That moisture coming up concerns me for any floor covering that supports mildew.

I think I'm going to contact a few of the floor leveling makers to discuss my situation. Having tried to seal it and paint it years ago, I'm not sure I can use one or not. All of them require a latex sealer as a bonding agent before using the leveler. All of them I've researched say the floor must be clear of efflorescence. I don't know if that just means vacuuming up the loose powder or that the concrete shouldn't produce efflorescence. If I can level the floor, I'd go with the dricore product since it leaves a space between the sub-floor and concrete so it can breathe. You also leave a 1/4" space along all walls. The de-humidifier will remove any moisture that comes out of the slab. That was my plan until I discovered how out of level the whole thing is.

 

[CHDinCT]

I usually find I have not done enough research on these types of projects. I would hate to see you do that work and buy the materials if it fails later. Not to offend, but I think you may be covering up an issue and hoping for the best.

One problem is the sleeper nails will all be penetrations of the vapor barrier. Another is you will probably have quite a bit of humidity fluctuation that isn't friendly to wood flooring. You could see cupping of the boards.

There is a lot of info out there, other people have confronted the same problems. It's just a matter of getting the right advice. You might try help boards operated by someone like Quikcrete or similar where you can post your situation and ask for recommendations. You never know what gems may be be uncovered. These folks are well regarded: Products You might ask about membranes that a floor "floats" on too rather than the nailing sleepers approach.

I would +1 the tile idea. But you still need to clean, bond, level, and maybe seal, the existing floor. Ceramic tile itself will take saturating conditions. The thin-set mortar used to bed the tile could be outdoor/exterior rated which ought to be moisture tolerant after curing like concrete. I think tile done right is your best chance of avoiding problems later.

No offense taken. I'm partly trying to find some great solution I haven't thought of or come across doing research. Since I run a industrial de-humidifier all year, I don't expect a lot of humidity variation. The unit is set at 53% humidity and I've never seen it vary more than a few percentage points. I know sleepers over a plastic vapor barrier has been done for years when finishing basements, so it works, but it's a bit old school. Just don't know if in my situation there's too much moisture to take a chance even with a vapor barrier. Nothing I can do about the nail penetrations, except maybe use an ice and water type roof sealer under the sleepers - just thought of that now actually.

 

[oldpilgrim]

20 years ago, I ramset the PT sleepers at 16" on center, then laid plastic over them. I pressed the plastic to the floor between the sleepers and inserted styrofoam between the sleepers over the plastic. Then came the 5/8 plywood and a carpet.

I had only a bit of dampness on the concrete before this job and this method has worked well all this time. The floor is dry and warm.

 

[dave1949]

No offense taken. I'm partly trying to find some great solution I haven't thought of or come across doing research. Since I run a industrial de-humidifier all year, I don't expect a lot of humidity variation. The unit is set at 53% humidity and I've never seen it vary more than a few percentage points. I know sleepers over a plastic vapor barrier has been done for years when finishing basements, so it works, but it's a bit old school. Just don't know if in my situation there's too much moisture to take a chance even with a vapor barrier. Nothing I can do about the nail penetrations, except maybe use an ice and water type roof sealer under the sleepers - just thought of that now actually.

Glad you weren't offended. Anything you could do to lower the ground moisture would make all flooring choices better and easier.

Any suspicions about the source of the moisture or any good way to get more drainage? If the concrete is really ugly it would be a lot easier (mentally at least ) to saw out some drain pipe channels if there is any gravel bed depth below the slab to work with.

I think it would drain a floor area somewhat if you cut the floor, dig a trench maybe 18" deep and put washed stone and a pvc drain pipe in--if you have somewhere to drain to or make a sump pit. The stone leaves a void that's easy for the water to seep into, the pipe takes it away. I guess the hardest part is deciding if anything that involved is really necessary.

Do you have radon gas to think about? Holes in basement floors, like sump pits or the joint between the slab and wall, are supposed to be a big source of radon.

 

[CHDinCT]

Glad you weren't offended. Anything you could do to lower the ground moisture would make all flooring choices better and easier.

Any suspicions about the source of the moisture or any good way to get more drainage? If the concrete is really ugly it would be a lot easier (mentally at least ) to saw out some drain pipe channels if there is any gravel bed depth below the slab to work with.

I think it would drain a floor area somewhat if you cut the floor, dig a trench maybe 18" deep and put washed stone and a pvc drain pipe in--if you have somewhere to drain to or make a sump pit. The stone leaves a void that's easy for the water to seep into, the pipe takes it away. I guess the hardest part is deciding if anything that involved is really necessary.

Do you have radon gas to think about? Holes in basement floors, like sump pits or the joint between the slab and wall, are supposed to be a big source of radon.

Not totally sure of the water source. I think there are some underground streams since I get sinking in my front yard that I've filled 3-4 times and the low spots just come back. I do have curtain drains that work. I can see water streaming out of the pipe after heavy rains. The builder left a 16"x16" cutout in the basement floor for a sump pump in case one was needed, but after 3-4 years without standing water I closed it up due to Radon fears, which I did test for many years ago. Showed very little back then - below the danger point. Suppose it could have changed. It is something I've thought of retesting for.

I did have a basement waterproofing company look at it last year. They said no need for an interior weeping system since I don't have leaks/standing water. Just said the best I could do was run a good dehumidifier to pull out what moisture comes through the slab.

 

[CHDinCT]

20 years ago, I ramset the PT sleepers at 16" on center, then laid plastic over them. I pressed the plastic to the floor between the sleepers and inserted styrofoam between the sleepers over the plastic. Then came the 5/8 plywood and a carpet.

I had only a bit of dampness on the concrete before this job and this method has worked well all this time. The floor is dry and warm.

Thanks. Interesting you put the plastic over the PT sleepers. That would avoid penetrations, just not sure what the long term result would be for the PT in my case given the high evaporation rate now.

 

[dave1949]

Not totally sure of the water source. I think there are some underground streams since I get sinking in my front yard that I've filled 3-4 times and the low spots just come back. I do have curtain drains that work. I can see water streaming out of the pipe after heavy rains. The builder left a 16"x16" cutout in the basement floor for a sump pump in case one was needed, but after 3-4 years without standing water I closed it up due to Radon fears, which I did test for many years ago. Showed very little back then - below the danger point. Suppose it could have changed. It is something I've thought of retesting for.

I did have a basement waterproofing company look at it last year. They said no need for an interior weeping system since I don't have leaks/standing water. Just said the best I could do was run a good dehumidifier to pull out what moisture comes through the slab.

I guess the waterproofing company decided the amount of moisture didn't warrant a lot of expense, that's good.

You are changing the situation with the dehumidifier if you cover the floor with a vapor barrier and flooring compared to bare concrete. With flooring and a barrier any humidity reaching the air would have to pass through the barrier and flooring before the dehumidifier could remove it. In effect, that may mean you are removing humidity from damp wood flooring versus damp concrete. That would be worst-case.

Best-case would be you put down the barrier and there isn't enough hydraulic pressure to penetrate any openings (from nails) and you live happily ever after. Your idea of using a membrane that would tend to seal the nail holes sounds good although I would check-out floating floor techniques too that would avoid those holes.

 

[bucktaker]

Not to Hijack but what Dehumidifer are you using? I have a cabin that we are fighting the humidity in the basement. Going to pull the subfloor and install new 6 mil plastic and run a good dehumidifer, its over a dirt floor

 

[CHDinCT]

Not to Hijack but what Dehumidifer are you using? I have a cabin that we are fighting the humidity in the basement. Going to pull the subfloor and install new 6 mil plastic and run a good dehumidifer, its over a dirt floor

This one:

https://www.youtube.com/watch?v=0TA6ANZELX8

Not cheap partly because you have to get it from a "Basement Systems" distributor, which I think are in every state. It's a franchise. Had them out to evaluate my situation. $1,700 was the price, but my basement stays at whatever level you set it at and never have to empty it, etc. I think they say that levels below 55% prevent mold/mildew from forming, so mine is set at 53%, but I could lower it.

Here's a better vid https://www.youtube.com/watch?v=6ugOQT8_jQk

By the way, it can be set up outside the area to be dehumidified and the intake and exhaust run via duct work.