"Sweat spots" on basement floor

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slownsteady

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Let's just say my basement renovation project is a long-term thing. I've started and stopped on it so many times it's starting to get silly.
For the most part, my walk-out basement is dry. But in the warm weather the floor gets these sweat spots...a small area of dampness here and there. Water doesn't form because it has enough ventilation, but as I am discovering now that I want to put flooring down, if I put plastic over the floor, the sweat spots become wet spots.
i have tried concrete resurfacer and I have treated with lithium silicate, but I have not slowed it down enough to cover with the vinyl floor covering I plan to use.
So what's my next step? Epoxy? Do I have to drill to relieve the pressure? Can I pipe to the outside on the lower side (the walk-out side) with some kind of open pipe system?
 

nealtw

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You have high water table and fill under the floor that does not allow movement to the low side. If you have a drain across the walkout. you may need to trench out from the wet areas. The perimeter around the high side is not working.
 

stadry

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some epoxies function as vapor barriers however they won't stop water which comes up & in above the floor elevation,,, think sub-floor drainage system + sump pump
 

joecaption

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No coating is going to stop water from coming up through the floor!
High water table is a valid issue, another is lack of gutters with drain tiles away from the foundation, mulch or flower beds forming forming ponds, no drain tiles around the foundation.
 

stadry

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defining 'drain tile' for younger folks: once upon a time, there was pipe named 'orangeburg' (https://en.wikipedia.org/wiki/Orangeburg_pipe),,, it became popular & was used in sewer lines & ext/int home sub-surface drain lines,,, there was also another fired clay product by the same name,,, it was often avail in 18" lengths & was often called 'tiles',,, generally 4" hdpe corrugated pipe is used now &, sometimes, its even installed correctly
 

Wuzzat?

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OK, high water table, but why only in warm weather? High humidity prevents the ever-present water from evaporating fast enough?

Does the location & pattern of wet spots give you any clues? Maybe you can rule out some causes.
You could drill small test holes to check for water table height, and then patch them, before committing to a major project.

I've also heard that some methods of excavation give an under-the-house high water table whereas the table is lower farther from the house where no earth was disturbed.

We have a sump pump.
One day we had 4" of rain and it was a day or two before the level went up by 2", so there was a time delay and some of the water went elsewhere.

A dehumidifier may work and so then you have a continuing cost to the PoCo vs. a large one-time lump sum of time or money for excavation.
You may need a dehumidifier anyway.

Speaking of sump pumps, I am not sure whether water touching the bottom surface of concrete is enough for it to wick to the top surface, or the water would have to be at or above the level of the top surface of concrete.

http://www.google.com/search?q="water+table"+for+Newton,+NJ&client=safari&rls=en&oq="water+table"+for+Newton,+NJ&gs_l=heirloom-serp.3...28086.32573.0.33005.2.2.0.0.0.0.386.438.1j3-1.2.0....0...1ac.1.34.heirloom-serp..2.0.0.8Ws1IPVR1DU
 
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stadry

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all wtr has to do is touch the conc floor's btm,,, from then on, its capillary action sucking up wtr

' One day we had 4" of rain and it was a day or two before the level went up by 2", so there was a time delay and some of the water went elsewhere.' its likely the wtr soaked into surrounding soil til said soil hit saturation point (rejection of more wtr)
 

slownsteady

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Gutters are in place and drain well beyond the house. No mulch or flower beds on the "walk-out side" (rear) of the basement. On the front side of the house, where the basement is below grade, there isn't any drain tiles to my knowledge.
I'm not too keen on drilling holes into the basement floor...seems like it would be a weak spot and invite water infiltration. I don't have a sump pit, and until i started thinking about this problem, I didn't think I needed one. I'm not too thrilled about having to put one in now.
I have been entertaining this wacky theory that if I drilled sideways below grade and under the slab to put in a pressure relief pipe that would drain to lower ground, that I could bleed off the water below the foundation. But I'm sure that would be an expensive experiment that I will never get around to.
 

stadry

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stdy, remember my nj bsmnt wtrproofing co yrs ago ? after 1st retirement ? bsmnt wtr can occur, even on top of a mountain, easier than 1 might think,,, look 1st to the buried sections of bsmnt walls,,,coring/drilling holes may cause wtr to take path of least resistance & bubble up out of them
 

Wuzzat?

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Each option could make things better, have no effect, or maybe even make things worse.

And which to try first, assuming you need more than one fix?

Hopefully doing one thing does not prevent your being able to do others.

This is quite a decision problem.
:hide:
 

Wuzzat?

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"Polyurethane foam injection uses a closed cell polymer foam to lift concrete slabs."
Maybe somebody makes foam that can be injected through the floor or from the perimeter that doesn't lift, only prevents water entry.
 

slownsteady

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"Polyurethane foam injection uses a closed cell polymer foam to lift concrete slabs."
Maybe somebody makes foam that can be injected through the floor or from the perimeter that doesn't lift, only prevents water entry.
Theoretically an interesting idea; a non-expanding foam. But if it didn't expand outward, you couldn't get it into enough of an area to make it work. But if it can expand outward, then it can expand upward.

Just thinking it through.......
 

stadry

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there is a method of subsealing using bentonite,,, did it w/ bsmnt walls in nyc,,, we'd submitted a well-point system but project engineer's thought they own'd the trump card,,, they didn't,,, polyurethane foam's best for filling voids,
raising conc, & sealing leaking cracks,,, not practical here, steady,,, HOWEVER,
call prime resins in conyers, ga - 800 something - harry gressette used to sub-seal conc floors to prevent moisture migration before he'd polish the conc,,, unfortunately he died before i could learn the process
btw, of course no $$ interest
 

Wuzzat?

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How 'bout a false floor 1" above the sweaty one?

Otherwise list the pro and cons of undesirable options and hold your nose.
Lump sums vs. continuing costs vs. risks & benefits vs. the likelihood the option doesn't work or only works for a while.
Sounds to me like at least one small sump pump or maybe even pond pumps, depending on how high you need to have the output pipe.

http://aces.nmsu.edu/pubs/_m/M227.pdf

Removing one cubic inch of water per day from your basement floor is .000003 GPM. You could borrow a dehumidifier for a few days to check this number.

Maybe can't use a pump. A porous floor covering with a layer of thin Nichrome heater wires underneath could probably evaporate this much as soon as the water surfaces.

And the spots may not be due to porous concrete. The floor temp along with the relative humidity in your basement may cause condensation on the colder areas of the floor. They reach the dew point. An IR meter can possibly confirm this.
 
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slownsteady

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A false floor above would be called the Dri-Core system, which I did look into. Can't afford to lose that much headroom in my basement, and I never did like the fact that they use OSB. If you get a flood instead of just a trickle, you're screwed.
 

slownsteady

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Just for the sake of argument......errr, I mean discussion; I'd like some feedback on the idea of a bleed-off pipe. Kind of based on the way they do radon mitigation. Probably not a DIY project unless you have access to the right equipment. And probably not cheap, but I imagine it could be done.

water mitigation idea.jpg
 

stadry

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zombies can also be added to non-resistable forces :hide: suppose its possible a relief perforated pipe drain would work,,, think, IF i were trying it, we'd grab sched 40 pvc & drill holes in it,,, not certain if the lighter s&d would have sufficient strength for insertion
 
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