Searching for source of water in basement

[Anonymous]

Wondering if anyone has had a similar situation. Our contractor was replacing part of our basement floor and found water underneath. He ended up removing the entire floor to see if he could figure out the source.

The water appears to be coming up from the ground and is only in the middle of the basement. This water isn’t being captured by our French drain bc it is in the middle of the room.

We have had some torrential rain over the past 6 weeks (since this was discovered) and no additional water has appeared.

Any ideas? The flooring contractor, our general contractor (not involved with this small project but came to see if he could help) and the French drain company are stumped.

[Anonymous]

If you think about it it doesn’t really matter where it came from you just need to give it a place to go should it rise up to a point above the basement slab.
Installing perforated drain pipe with a 1/8” per foot slope in the direction of your existing sump crock will give the water a place to go when it does inevitably rise. you don’t say but the entire basement slab sounds like it’s been chopped up already so lay the pipe, fix your floor and everything will be fine.

it’s more than a little troubling that the basement waterproofing company said they were “stumped”, i’d source a few more opinions and hopefully find someone familiar with the physical properties of groundwater.

[Anonymous]

Is there a bathroom in the basement? Possible plumbing issue?

[Anonymous]

Anonymous wrote:Wondering if anyone has had a similar situation. Our contractor was replacing part of our basement floor and found water underneath. He ended up removing the entire floor to see if he could figure out the source.

The water appears to be coming up from the ground and is only in the middle of the basement. This water isn’t being captured by our French drain bc it is in the middle of the room.

We have had some torrential rain over the past 6 weeks (since this was discovered) and no additional water has appeared.

Any ideas? The flooring contractor, our general contractor (not involved with this small project but came to see if he could help) and the French drain company are stumped.

This can just be trapped condensation. There was a time I left a large plastic cutting mat on our unfinished basement floor (cement slab). Later I picked it up and there was water under it. I thought someone had spilled something without telling me. I cleaned up and put it back and the water returned. So lesson learned, no sheets of plastic on the floor. Our basement was not wet otherwise, but we ran a dehumidifier all summer.

[Anonymous]

Just run a condenser all the time

[Anonymous]

Anonymous wrote:

Anonymous wrote:Wondering if anyone has had a similar situation. Our contractor was replacing part of our basement floor and found water underneath. He ended up removing the entire floor to see if he could figure out the source.

The water appears to be coming up from the ground and is only in the middle of the basement. This water isn’t being captured by our French drain bc it is in the middle of the room.

We have had some torrential rain over the past 6 weeks (since this was discovered) and no additional water has appeared.

Any ideas? The flooring contractor, our general contractor (not involved with this small project but came to see if he could help) and the French drain company are stumped.

This can just be trapped condensation. There was a time I left a large plastic cutting mat on our unfinished basement floor (cement slab). Later I picked it up and there was water under it. I thought someone had spilled something without telling me. I cleaned up and put it back and the water returned. So lesson learned, no sheets of plastic on the floor. Our basement was not wet otherwise, but we ran a dehumidifier all summer.

What you're describing is called "rising damp" and it's moisture that is coming up from the damp soil below and through the concrete due to capillary action. It's caused by not having a vapor barrier under your basement slab. The last thing you want to do is let that moisture into your house, because the soil below is going to be essentially a limitless supply. What you want is a vapor barrier of some sort. A sheet of plastic works if the area has a floor over or has low traffic. To hold up to higher traffic you want a vapor barrier primer and a layer of paint over it to protect it. Make sure the primer you use is labeled as a vapor barrier, most aren't. Waterproof paint like Drylok is generally not a good vapor barrier either.

[Anonymous]

What I would do since the floor is up is dig a small test pit. In 99% of cases where it's suggested that the problem is a "high water table" that's not actually the case, but given your description I'd say it's either a plumbing leak under the floor or indeed a high water table.

If you dig a test pit, you'll get an idea of what the water is doing. As the name suggests, a "water table" is a flat underground layer of water. If you dig a pit the pit will fill to the level of the water table and no further, and as you dig the soil below the water table will be completely saturated. If it's a leak the pit will probably be dry but might fill as the water from the leak finds it way in.

My money's on the leak. But if it is the high water table you can divert the water into your interior drains as another poster suggested.

[Anonymous]

In addition check the grading of your house.
Water should flow away from the house.

[Anonymous]

Op here. Thanks for all the tips. There is an old vinyl floor - our LVT was put on top of it. Our flooring guy has been looking into putting some sort of waterproof epoxy on the floor. Maybe that is similar to a water barrier. I don’t will run all of these by the contractors.

Btw, grading is away from the house.

[Anonymous]

Anonymous wrote:What I would do since the floor is up is dig a small test pit. In 99% of cases where it's suggested that the problem is a "high water table" that's not actually the case, but given your description I'd say it's either a plumbing leak under the floor or indeed a high water table.

If you dig a test pit, you'll get an idea of what the water is doing. As the name suggests, a "water table" is a flat underground layer of water. If you dig a pit the pit will fill to the level of the water table and no further, and as you dig the soil below the water table will be completely saturated. If it's a leak the pit will probably be dry but might fill as the water from the leak finds it way in.

My money's on the leak. But if it is the high water table you can divert the water into your interior drains as another poster suggested.

If there is a leak, wouldn’t we be seeing water regularly?

[Anonymous]

Do you have a sump pump?

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:Wondering if anyone has had a similar situation. Our contractor was replacing part of our basement floor and found water underneath. He ended up removing the entire floor to see if he could figure out the source.

The water appears to be coming up from the ground and is only in the middle of the basement. This water isn’t being captured by our French drain bc it is in the middle of the room.

We have had some torrential rain over the past 6 weeks (since this was discovered) and no additional water has appeared.

Any ideas? The flooring contractor, our general contractor (not involved with this small project but came to see if he could help) and the French drain company are stumped.

This can just be trapped condensation. There was a time I left a large plastic cutting mat on our unfinished basement floor (cement slab). Later I picked it up and there was water under it. I thought someone had spilled something without telling me. I cleaned up and put it back and the water returned. So lesson learned, no sheets of plastic on the floor. Our basement was not wet otherwise, but we ran a dehumidifier all summer.

What you're describing is called "rising damp" and it's moisture that is coming up from the damp soil below and through the concrete due to capillary action. It's caused by not having a vapor barrier under your basement slab. The last thing you want to do is let that moisture into your house, because the soil below is going to be essentially a limitless supply. What you want is a vapor barrier of some sort. A sheet of plastic works if the area has a floor over or has low traffic. To hold up to higher traffic you want a vapor barrier primer and a layer of paint over it to protect it. Make sure the primer you use is labeled as a vapor barrier, most aren't. Waterproof paint like Drylok is generally not a good vapor barrier either.

Thanks for the superior explanation. Yes this was an unfinished basement, 1940s technology. I don't think there was any sort of barrier, and assumed OP could be dealing with similar. Just surprised the contractor is looking for active leaks in that case when there's a simpler explination.

[Anonymous]

Anonymous wrote:Just run a condenser all the time

That doesn't make any sense at all.