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Started By
Message
Need Advice for a sweating house slab ruining my floors
Posted on 9/8/25 at 8:01 am
Posted on 9/8/25 at 8:01 am
Timeline:
1. bought flipped house in 2019 in metairie, la. Full underslab sewer line replaced at this time.
2. in 2023 engineered hardwood Floor boards started showing black spots in multiple location, so got floor boards pulled up and found that the slab was moist underneath.
3. filed insurance claim to get floor replaced. insurance sent out american leak detectors and found no leak. I also checked my water meter and confirmed that the meter was not moving. claim denied.
4. in Spring 2024, We moved forward with getting the entire house floors replaced. They removed the floors let the slab dry for 4 days, then put down 2 coats of slab sealent that is meant to deter 99% of moisture up to i think 25 psf. then put a visquine vapor barrier and then put down LVP flooring with built in backing.
5. Summer 2024 we had some boards popping up and the flooring company came out and investigated the hallway and found some moisture underneath a small section of floor boards popping up. They fixed it but this happended 3 more times in this area.
6. August 2025, a 4'x4' "bubble" has formed under the flooring in the den which is 30 feet from the hallway. Flooring company came out to investigate and found moisture under the entire left side of my floor (30'x8') and did not find the edge of the moisture covered vapor barrier, so it could be throughout the whole house. Our sewer main was replaced in 2019 under our house. Our roof was replaced in 2020. The flooring company thinks water is getting into the slab somehow whether its high water table or a leak of somekind. None of my neighbors have complained of floor issues which makes me beleive that the high water table is not an issue as our houses are at the same elevation.
7. What else could be the cause of this issue and how can i fix it? I am running out of options.
Other tidbits:
no pools in my niehgbors houses. Floor guy mentions he's only seen water get thru the slab sealant once and it was from a neighbors pool leaking.
no soft or squishy spots in the yard.
Have gutters and water does not pool next to the slab during rain events.
I checked the meters of my neighbors for leaks and saw nothing.
1. bought flipped house in 2019 in metairie, la. Full underslab sewer line replaced at this time.
2. in 2023 engineered hardwood Floor boards started showing black spots in multiple location, so got floor boards pulled up and found that the slab was moist underneath.
3. filed insurance claim to get floor replaced. insurance sent out american leak detectors and found no leak. I also checked my water meter and confirmed that the meter was not moving. claim denied.
4. in Spring 2024, We moved forward with getting the entire house floors replaced. They removed the floors let the slab dry for 4 days, then put down 2 coats of slab sealent that is meant to deter 99% of moisture up to i think 25 psf. then put a visquine vapor barrier and then put down LVP flooring with built in backing.
5. Summer 2024 we had some boards popping up and the flooring company came out and investigated the hallway and found some moisture underneath a small section of floor boards popping up. They fixed it but this happended 3 more times in this area.
6. August 2025, a 4'x4' "bubble" has formed under the flooring in the den which is 30 feet from the hallway. Flooring company came out to investigate and found moisture under the entire left side of my floor (30'x8') and did not find the edge of the moisture covered vapor barrier, so it could be throughout the whole house. Our sewer main was replaced in 2019 under our house. Our roof was replaced in 2020. The flooring company thinks water is getting into the slab somehow whether its high water table or a leak of somekind. None of my neighbors have complained of floor issues which makes me beleive that the high water table is not an issue as our houses are at the same elevation.
7. What else could be the cause of this issue and how can i fix it? I am running out of options.
Other tidbits:
no pools in my niehgbors houses. Floor guy mentions he's only seen water get thru the slab sealant once and it was from a neighbors pool leaking.
no soft or squishy spots in the yard.
Have gutters and water does not pool next to the slab during rain events.
I checked the meters of my neighbors for leaks and saw nothing.
11
Posted on 9/8/25 at 8:15 am to Tmar1no
I feel for you.
I am currently in a similar situation and we do not have answers either.
We are at the stage where the engineered hardwoods have black spots. Floor inspector confirmed installer did not prep floor properly, or install moisture barrier as required by adhesive manufacturer..
I have lived in the house 30 years and there was never any signs of water with previous wood floors. installed engineered wood after flood of 2021, got hardly any water, let slab sit for 3 months, and then within a year see the dark spots.
Tried to get insurance and installer to replace but no luck. Leak detector found nothing.
Our plan is to remove floors, test, install sealant, and maybe do some ceramic faux wood floors incase we are unable to fix the issue. BUT finding the money, and time to move out of house, has been hard.
We do not know what could be causing this, we are higher than neighbors and none of them have issues.
One guy told me that not having gutters could be a reason? Has anyone told you that?
Were you successful in getting insurance to replace the engineered wood floors? or did you have to come out of pocket?
I am currently in a similar situation and we do not have answers either.
We are at the stage where the engineered hardwoods have black spots. Floor inspector confirmed installer did not prep floor properly, or install moisture barrier as required by adhesive manufacturer..
I have lived in the house 30 years and there was never any signs of water with previous wood floors. installed engineered wood after flood of 2021, got hardly any water, let slab sit for 3 months, and then within a year see the dark spots.
Tried to get insurance and installer to replace but no luck. Leak detector found nothing.
Our plan is to remove floors, test, install sealant, and maybe do some ceramic faux wood floors incase we are unable to fix the issue. BUT finding the money, and time to move out of house, has been hard.
We do not know what could be causing this, we are higher than neighbors and none of them have issues.
One guy told me that not having gutters could be a reason? Has anyone told you that?
Were you successful in getting insurance to replace the engineered wood floors? or did you have to come out of pocket?
Posted on 9/8/25 at 8:32 am to MLSter
Insurance claim denied because it did not happen from a single event like a flood or leak or leaving the sink running, so we came out of pocket. (Pissed me off BTW)
My flooring guy has been working with us every step and has been great.
I have found one possible band-aid solution if i cannot stop the vapor from entering. Looking into basement construction in other parts of the country, they install subfloors that have little feet to lift off the consrete beneath the LVP to allow the moisture in then allow it to evaporate instead of the moisture sticking to the vapor barrier like it is now. If i cant fix the water infiltration issue, this is what i will be bringing to my floor guy to see if he will work with us.
My flooring guy has been working with us every step and has been great.
I have found one possible band-aid solution if i cannot stop the vapor from entering. Looking into basement construction in other parts of the country, they install subfloors that have little feet to lift off the consrete beneath the LVP to allow the moisture in then allow it to evaporate instead of the moisture sticking to the vapor barrier like it is now. If i cant fix the water infiltration issue, this is what i will be bringing to my floor guy to see if he will work with us.
Posted on 9/8/25 at 8:57 am to Tmar1no
Seems like somebody has not found the leak YET. Seems hard to believe you would have this much trouble without an active leak. Just a hunch tho. Sounds like a certified nightmare.
Posted on 9/8/25 at 8:57 am to sosaysmorvant
It is definitely a nightmare.
Posted on 9/8/25 at 10:52 am to Tmar1no
Sounds like my parents home that we just mitigated.
Older home, likely concrete slab doesnt have a vapor barrier. We had some of the same issues.
What we did after removing the old flooring:
1) concrete sealant
2) epoxy over the entire concrete floor
3) replaced the flooring
We still had a couple of spots that wanted to buckle a bit, but that was mostly an installation too tight issus, which was alleviated by just putting some transition strips in some areas instead of having a cohesive floor as one unit. There was no moisture underneath any of the boards we picked up to refit.
Aside from that we did put some gutters up in some spots, along with a French drain/catch basin in a couple of spots where water wants to collect near the slab.
But since then theres never been any other moisture issues.
The only other option we briefly looked into was to have a company come out and look at doing an encapsulation project around the slab to help prevent inteusion.
Older home, likely concrete slab doesnt have a vapor barrier. We had some of the same issues.
What we did after removing the old flooring:
1) concrete sealant
2) epoxy over the entire concrete floor
3) replaced the flooring
We still had a couple of spots that wanted to buckle a bit, but that was mostly an installation too tight issus, which was alleviated by just putting some transition strips in some areas instead of having a cohesive floor as one unit. There was no moisture underneath any of the boards we picked up to refit.
Aside from that we did put some gutters up in some spots, along with a French drain/catch basin in a couple of spots where water wants to collect near the slab.
But since then theres never been any other moisture issues.
The only other option we briefly looked into was to have a company come out and look at doing an encapsulation project around the slab to help prevent inteusion.
Posted on 9/8/25 at 1:59 pm to Tmar1no
Sounds like a nightmare.
I'd start by digging a few holes around the perimeter and see if there is any groundwater seepage. Have to do this not too long after rain but obviously not while rain predicted for few days to let holes sit.
Also look at areas where water might puddle up from rain near slab. Install gutter and drainpipe to get away from slab.
A French drain around perimeter of home may be the solution. Better if can run drain to daylight and not rely on pump to fail.
I can see where even a sealer and visqueen could fail to help if slab was wet with water. You can't seal or put visqueen under things like cabinets or walls. If water accumulates enough it will go sideways under visqueen until it finds a hole or seam.
You happen to be one of those people that keep their home at 68* in summer by chance?
I'd start by digging a few holes around the perimeter and see if there is any groundwater seepage. Have to do this not too long after rain but obviously not while rain predicted for few days to let holes sit.
Also look at areas where water might puddle up from rain near slab. Install gutter and drainpipe to get away from slab.
A French drain around perimeter of home may be the solution. Better if can run drain to daylight and not rely on pump to fail.
I can see where even a sealer and visqueen could fail to help if slab was wet with water. You can't seal or put visqueen under things like cabinets or walls. If water accumulates enough it will go sideways under visqueen until it finds a hole or seam.
You happen to be one of those people that keep their home at 68* in summer by chance?
Posted on 9/8/25 at 2:14 pm to Tmar1no
I've seen this happen before when a vapor barrier was not installed under the slab by the original builder. For older homes (60s, 70s, 80s ranchers), it wasn't usually a problem because they had a lot of carpet and the moisture was able to escape/evaporate. Its not until wood or vinyl is installed throughout that the issue really presents itself.
A good epoxy concrete sealer should work but there's also a dimple membrane you can install to separate the floor from the slab. If it was me, I'd use both.
A good epoxy concrete sealer should work but there's also a dimple membrane you can install to separate the floor from the slab. If it was me, I'd use both.
Posted on 9/8/25 at 3:15 pm to Tmar1no
It might be condensation. I’ve seen this on LVP and wood flooring, just never on a slab on grade.
Owner typically runs the air-conditioning cold as hell and creates dewpoint conditions at the vapor barrier under the LVP or on the LVP itself.
Put a couple of dehumidifiers in the house and check after a week. If that fixes the problem, install a permanent dehumidifier in your HVAC system.
Owner typically runs the air-conditioning cold as hell and creates dewpoint conditions at the vapor barrier under the LVP or on the LVP itself.
Put a couple of dehumidifiers in the house and check after a week. If that fixes the problem, install a permanent dehumidifier in your HVAC system.
This post was edited on 9/8/25 at 3:21 pm
Posted on 9/8/25 at 3:56 pm to Tmar1no
quote:
6. August 2025, a 4'x4' "bubble" has formed under the flooring
This is what makes me think it has to be a pressurized leak. If it were groundwater, humidity under the lvp would reach 100% and then it should stop wicking. You'll have dampness and probably mold, but not enough to bubble or lift the floor.
Posted on 9/8/25 at 5:36 pm to Tmar1no
You don't provide detail about the under-slab sewer replacement, but I have to wonder why it was needed. The flipper may have been trying to fix a wet slab, or the fix may have allowed the infiltration you see now. Did Leak Detectors pressurize and test for sewer leaks? They often look only for leaks in supply lines.
Metairie is so flat that there isn't much you can do about drainage ( if that is your problem) except dig sumps and use pumps. A problem in very flat subdivisions about 50 years old is that landscaping eventually raises the yard above the level of the slab. Regrading parts of the yard might help.
Good luck.
Metairie is so flat that there isn't much you can do about drainage ( if that is your problem) except dig sumps and use pumps. A problem in very flat subdivisions about 50 years old is that landscaping eventually raises the yard above the level of the slab. Regrading parts of the yard might help.
Good luck.
Posted on 9/8/25 at 7:31 pm to Tmar1no
I just went through this. We were replacing our old laminate; the sound-deadening under the laminate was water-impermeable, so it trapped the moisture under it. They stopped the install after the demo until we mitigated the issue. checked for leaks, etc. We were at the slab, and it dried out within a day.
We did a test where we taped down a 2' x 2' piece of clear poly sheeting (visqueen). The area under the plastic got wet again, but the poly did not tent up (make a bubble).
That pretty much verified that it was water wicking into the slab (the house was built in 1981) due to a lack of a vapor barrier, but not actual hydraulic pressure from the water table or standing water.
We were going in with wood-look ceramic tile, so our options were limited. The solution was to use a product designed to put tiles in pools and wet areas. It seals, contains Microban, and can be used indoors.
If you want to go back with a floating floor, you will probably need to seal the concrete; an epoxy would probably be a good solution. But that is not a good solution if you are ever considering any that need to be "glued" down like a ceramic or natural stone.
One of the oddities for this situation that also would point to either no vapor barrier of a seriously compromised one is what the slab looks like under any carpet you have. If it is simply wicking water, it will evaporate through the padding and carpet faster than it can create issues, and the slab will look dry when you pull up the carpet.
We did a test where we taped down a 2' x 2' piece of clear poly sheeting (visqueen). The area under the plastic got wet again, but the poly did not tent up (make a bubble).
That pretty much verified that it was water wicking into the slab (the house was built in 1981) due to a lack of a vapor barrier, but not actual hydraulic pressure from the water table or standing water.
We were going in with wood-look ceramic tile, so our options were limited. The solution was to use a product designed to put tiles in pools and wet areas. It seals, contains Microban, and can be used indoors.
If you want to go back with a floating floor, you will probably need to seal the concrete; an epoxy would probably be a good solution. But that is not a good solution if you are ever considering any that need to be "glued" down like a ceramic or natural stone.
One of the oddities for this situation that also would point to either no vapor barrier of a seriously compromised one is what the slab looks like under any carpet you have. If it is simply wicking water, it will evaporate through the padding and carpet faster than it can create issues, and the slab will look dry when you pull up the carpet.
Posted on 9/8/25 at 7:58 pm to Tmar1no
Wet weather spring under home?
Posted on 9/8/25 at 8:15 pm to mdomingue
1. The lot camel backs very well and water does not pool up next to the house
2. AC stays around 70 year round, not very comfortable much higher
3. Sewer line replaced by the flipper 1 week after buying the house. We knew about a small sag and terracotta when we bought it and then it backed up the first week. Had an independent plumber friend inspect the job was done correctly. Also had the plumbing inspected today and have no leaks.
4. 8’x30’ section of slab has been exposed for 1 week now and it’s dry, board right next to open slab has visquean sticking out and I can see moisture under neath.
5. The only possible fix I have seen was researching basement flooring and the subfloor with the dimples to allow for the moisture to evaporate. Anybody else have experience with this? I have to ask my flooring guy if he’s willing to remove and reinstall the floors and I would pay for the subfloor. Seems unlikely but worth a shot.
6. I am not sure what the leak detection ppl did but it was thru insurance so I assume he was thorough.
I think that’s all the questions
2. AC stays around 70 year round, not very comfortable much higher
3. Sewer line replaced by the flipper 1 week after buying the house. We knew about a small sag and terracotta when we bought it and then it backed up the first week. Had an independent plumber friend inspect the job was done correctly. Also had the plumbing inspected today and have no leaks.
4. 8’x30’ section of slab has been exposed for 1 week now and it’s dry, board right next to open slab has visquean sticking out and I can see moisture under neath.
5. The only possible fix I have seen was researching basement flooring and the subfloor with the dimples to allow for the moisture to evaporate. Anybody else have experience with this? I have to ask my flooring guy if he’s willing to remove and reinstall the floors and I would pay for the subfloor. Seems unlikely but worth a shot.
6. I am not sure what the leak detection ppl did but it was thru insurance so I assume he was thorough.
I think that’s all the questions
This post was edited on 9/8/25 at 8:16 pm
Posted on 9/10/25 at 7:00 pm to Tmar1no
As a former master plumber I would see this pretty often, first check the ac ducts aren't blowing on the areas getting moisture, get a leak detection done on the house water lines. Unless your below grade its probably not groundwater (unless your near the M River and it only occurs during flood season) When I would break up slabs to determine issues when none was apparent there would usually be a disintegrated plastic vapor barrier (Don't know why they would do that under a slab, but they do!) or a improperly installed vapor barrier. There is some concrete sealers that help but solid wood floors are pretty much out. Laminate floors over vapor barriers are your best bet if its widespread.
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