Moisture from slab warped wood floor - how to replace?

[soupcxan]

A few years ago we had all the floors in our 1960s house (slab on grade foundation) in Houston replaced with a mix of tile, carpet, and a floating engineered wood (not hardwood, but also not cheapo laminate). For the wood floor, the slab was "floated" up as needed to make it level, then a vapor barrier was installed (basically a plastic sheet was taped down), and a 3/32" foam pad on top. Then the wood was glued together with it's tongue and groove on top. A 1/2" gap was left under the baseboards for expansion.

The wood floor problems started within the first year, lots of cracking and popping. One room in particular developed a significant buckling. The contractor came out and tried a couple of fixes but eventually re-did that room. But the problem came back even worse than before, there was ~4x4' bubble in the floor you could feel walking on it.

We just pulled the floor up again and found that the float had separated from the foundation and bubbled up, and that is what pushed up the wood floor. And that the float was damp to the touch. No interior source of water (a leak) was identified. Once exposed to the air, the area seemed to dry out fairly quickly.

So, we are done with wood in that room and thinking of using carpet - but can we install normal carpet pad and carpet on slab like we did in the other rooms, or do we need a vapor barrier or some other precaution?

Part of me thinks that carpet will be able to breathe where the wood floor couldn't because of the vapor barrier, so moisture won't accumulate. The other part of me thinks the carpet and pad will suck up the moisture from the slab and turn into a mildew swamp.

Frankly at this point I don't have much confidence in my contractor (though at least so far, he has warranteed his work) so looking for other opinions.

 

[GrayHare]

The water is going to be a problem no matter what flooring you use. Might water be entering at the edge of the slab then pooling at a low spot? Sometimes the leaks can be difficult to find but once you fix that you have many flooring options.

 

[haha]

The water is going to be a problem no matter what flooring you use. Might water be entering at the edge of the slab then pooling at a low spot? Sometimes the leaks can be difficult to find but once you fix that you have many flooring options.

Agree. If you can figure it out, fix it. Otherwise you can top with a porous tile, or finish the concrete floor. Both of these can be very hardy and attractive, but also an unpleasant place to fall.

Ha

 

[Hermit]

I had padding and carpet in my basement in Denver many years ago. It worked just fine except when I put a rubber mat down under a tread mill. When I picked up the rubber mat many weeks later the carpet was wet and slightly stained where the mat was. We moved the tread mill off the carpet and got the stain out and didn't have any more problems.

 

[Freedom56]

The problem can be caused by moisture under your slab. In new construction, they put a moisture barrier under the slab in situations (excessive ground moisture) where this can be a problem plus adjust the water ratio in the concrete mixture. Did someone check the humidity level of the concrete slab after the flooring was removed? If the relative humidity in the concrete slab is different than the relative humidity of the air above the slab, then moisture is going to try to move in or out of the slab. Without a vapor barrier, the relative humidity in the slab just below the surface can often be 100%. Since the air is seldom that humid, moisture is going to move from the slab into the air and as the surface dries a bit it will draw moisture up from the bottom. From your description, this is what appears to be happening. When carpet, wood, or vinyl flooring is installed over damp concrete, moisture creates real havoc, since the dampness and high alkalinity will lead to mold, emulsified adhesives, and warped flooring. I agree with the previous post, you need to fix the moisture problem before installing new flooring. Are you sure that you don't have any drain pipes running under the impacted areas?

 

[aja8888]

OP is in Houston where we are. Everything here is built on a slab.

Under Houston (very shallow) is the relatively impermeable Beaumont Clay formation just a shovel away, in most cases. Older homes had problems with foundations shifting and raising/settling and becoming cracked. As stated above, without a moisture barrier and "cable lock" construction, you can expect foundation issues.

 

[soupcxan]

Don’t think I have any drain pipes under the affected area, it’s not close to bathrooms or the kitchen. I would’ve expected areas in other rooms closer to the water fixtures to pick up problems first.

Not sure how else to find the source of the water - doesn’t seem to be coming down the wall. We certainly have had plenty of rain in Houston in the last couple years. I doubt foundations of this era were built with a vapor barrier underneath, but I doubt one can be added now?

 

[Meadbh]

I expect the water table under Houston is pretty high right now. I am not an engineer, but I wonder if your house may be floating on mud. In your situation, I would hire a structural engineer to assess the problem.

 

[CaliKid]

We had very similar and finally found a very small leak in a window. That was caused from a leak in a roof-line gutter that caused water to drip in one spot on the window. The water got into the wall from there, down to the floor, and then across the hard wood floor. It was very hard to find as the water had spread out. I would look everywhere. Even look a ways away where you don't think it is possible the leak could come from.

 

[Freedom56]

Don’t think I have any drain pipes under the affected area, it’s not close to bathrooms or the kitchen. I would’ve expected areas in other rooms closer to the water fixtures to pick up problems first.

Not sure how else to find the source of the water - doesn’t seem to be coming down the wall. We certainly have had plenty of rain in Houston in the last couple years. I doubt foundations of this era were built with a vapor barrier underneath, but I doubt one can be added now?

Cover the area with clear plastic (at least 2 mil) over the floor for a few days and see if you see any condensation on the plastic. Your flooring contractor should have done this before installing the floor on your slab or tested for moisture. If you see condensation, dry up the area and put a few coats of "drylok" over the area and repeat the test. It won't cost you much to do this test. A one gallon which covers about 1000 sq ft costs about $23 at Home Depot. Repeat the test with the plastic and see if it solves your problem. Leave the plastic on the floor for a couple of weeks to be sure it works.

 

[6miths]

For a more expensive solution one might try DRIcore subfloor products. I put one of these down on the basement floor in the cottage several years ago and problems solved. They offer various products for different problems. Insulated subfloor, subfloor that allows drainage and air circulation beneath and combinations of both.

 

[pb4uski]

Agree with others.... job one is to try to identify what is causing the problem. Until you think the problem has been identified and addressed, I would consider using inexpensive carpet tile that can be easily removed and replaced if needed.

 

[Lakewood90712]

Moisture retarders are only as good as the care and installation. ( it retards the flow of moisture , not really a barrier). And adding one where it was not originally installed and intended, requires thought , will it create a problem, rather than prevent one ?.

Think of concrete crews intentionally punching holes in the plastic moisture retarder under a slab so the concrete would set up faster. Some of the ugly outrageous things with tract homes . Although rare these days, this stupid practice did happen in the 1960's, 70's and 80's, mostly in the west.

Concrete passes moisture in and out.

? What were the floors before? Carpet ?

 

[davebarnes]

Rip out the slab and replace with a foundation+ crawl space.

 

[nwsteve]

Agree with others.... job one is to try to identify what is causing the problem. Until you think the problem has been identified and addressed, I would consider using inexpensive carpet tile that can be easily removed and replaced if needed.

Here is another option--luxury vinyl tile/planks--

https://www.homedepot.com/b/Search/...-luxury+vinyl?Ntx=mode+matchpartialmax&NCNI-5

I have seen this stuff in mid-market major brand )hotels baths ((Marriott Springhill Suites) including showers. Looks great. Our rental property mgr told me it is their go to for basements, kitchens, and hi-traffic areas. Said he has not had failure yet.

 

[aja8888]

Rip out the slab and replace with a foundation+ crawl space.

Not routinely done in Houston due to the Beaumont Clay and shifting and soil contraction/expansion that goes on here. When we have droughts (and we have them), the subsurface clay layer dries up and we have cracks in the surface soils. A practice here is to wet the perimeter of your foundation enough to keep the clay moist during droughts.

New slabs here a "cable locked" - put in compression with cables tightened in a zig zag pattern through the cross section of the slab.

 

[Sunset]

Perhaps OP has a water issue like I used to have.

Any possibility rainwater is being deposited by your downspouts right at the edge of the house causing the area to be saturated with water and putting great water pressure on your slab ?

I added downspouts to the end of ours to deposit the water many feet from the house, and our sump pump now only has to work about 10% of what it used to do.

 

[txtig]

We have engineered wood flooring (same as OP) installed on a post-tensioned concrete slab in the Houston area. Floor is about 14 years old and was glued to the slab after it was sealed with a liquid sealant. So far, no problems, at least not due to moisture. Getting ready to have the floor refinished. Lots of wear and tear from our kiddos and now the grand kids.

 

[soupcxan]

Most of the house doesn't have gutters/downspouts. Given it's been there 50 years without them I assumed they weren't a priority to add but maybe that's part of the issue.

The previous flooring was some cheapo laminate. Not sure how long the previous owners had it or how well it held up to the moisture, we removed it pretty quickly.


I'm not aware that any moisture tests were done before the floor was installed. I'll tape down a plastic sheet and see if moisture comes up.

I guess I should get a foundation guy to look at it before putting new carpet down.

 

[Meadbh]

Most of the house doesn't have gutters/downspouts. Given it's been there 50 years without them I assumed they weren't a priority to add but maybe that's part of the issue.
..........
I guess I should get a foundation guy to look at it before putting new carpet down.

Well, yes, because if you don’t deal with the root cause, that will be money down the drain!

 

[soupcxan]

Well, yes, because if you don’t deal with the root cause, that will be money down the drain!

Perhaps, but my other thought is that several other rooms have carpet on the slab and no issues...so either the slab in this room is particularly wet, or all the slabs are equally wet and the carpet allows them to breathe while the wood/vapor barrier did not...but I really don't know...

 

[Big_Hitter]

OP is in Houston where we are. Everything here is built on a slab.

we had a house in houston that was pier and beam - it was built in 1926 though

 

[Lakewood90712]

Another thing to consider, moisture in a concrete slab normally migrates to the warmest surface.

 

[Scrapr]

The problem can be caused by moisture under your slab. In new construction, they put a moisture barrier under the slab in situations (excessive ground moisture) where this can be a problem plus adjust the water ratio in the concrete mixture. Did someone check the humidity level of the concrete slab after the flooring was removed? If the relative humidity in the concrete slab is different than the relative humidity of the air above the slab, then moisture is going to try to move in or out of the slab. Without a vapor barrier, the relative humidity in the slab just below the surface can often be 100%. Since the air is seldom that humid, moisture is going to move from the slab into the air and as the surface dries a bit it will draw moisture up from the bottom. From your description, this is what appears to be happening. When carpet, wood, or vinyl flooring is installed over damp concrete, moisture creates real havoc, since the dampness and high alkalinity will lead to mold, emulsified adhesives, and warped flooring. I agree with the previous post, you need to fix the moisture problem before installing new flooring. Are you sure that you don't have any drain pipes running under the impacted areas?

Freedom56 summarized my thoughts very well. Concrete is porous. Water moves through it

I'm not sure what can be done about it. Probably above the pay grade of a foundation guy though

Trust him...he's pre med

https://youtu.be/uepFO4psgKE

 

[Sunset]

OP - do you have a sump pump ?