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Do I have drainage tile lines? Sump pit/water questions

Do I have drainage tile lines? Sump pit/water questions


  #1  
Old 06-13-13, 11:35 AM
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Do I have drainage tile lines? Sump pit/water questions

Hi all,
I've been scouring the internet for answers and I can't find quite what I'm looking for, so I figured I'd ask here!

So, my situation is I bought a house built in the 70's, no apparent issues upon inspection. The basement is mostly finished, drywalled and the previous owners had carpet that we tore out because it got wet from the hot water heater flooding the basement when the city turned our water on.

I had a concrete slab to cover in the basement, so I bought no-glue sheet vinyl and installed it. I noticed that once spring arrived and it started raining, I got moisture underneath the sheet vinyl. I pulled it up, dried everything, installed a dehumidifier and put it back down. It rained a lot last week and I noticed the moisture had returned underneath the sheet vinyl.

I pulled everything back up, dried it, and taped some plastic sheets down to the now dry concrete. I pulled up the plastic the next day and the concrete underneath the sheets was wet, not standing water, but enough to towel off, like condensation. The rest of the floor remained dry.

I assume what this means is that the hydrostatic pressure of the groundwater is pushing water through the concrete slab and I never noticed it before because it was evaporating quickly enough to not pool water. It has been 5 days since it rained and moisture is still able to come up through the concrete, but I bet the water table is quite high right now (the river is still flooded) even though it hasn't rained recently.

I checked my sump pit when I did the plastic sheet test and it was damp, but no standing water and I haven’t heard the sump-pump run. Attached is a picture of my pit. I’m a bit confused by it because it looks like I don’t have drain tile lines; it looks like a pit in the ground with holes. Is that actually what it is, or are there tile lines that I can’t see? Being as the house was built in the 70’s I assumed the house had foundation drain tiles, but perhaps not. The moisture issues I've found definitely suggest something is not right with the drainage underneath the slab, assuming there is any... I have gutters and downspouts ~5 feet away from the foundation, and I'm going to regrade the foundation next week as it's not quite minimim slope, but I doubt that will fix the problem entirely.

TL;DR
Can anyone tell me if tile lines were required in the 70’s and I do have them based upon the picture of my pit, or if it’s possible I just have a pit with no drainage tile linking into it?
Is the only surefire way to tell by digging down around the foundation to check for a footer drainage tile?

Additional bonus question:
Can I seal the basement floor and prevent this seepage? How do I check the PSI of the hydrostatic pressure to ensure that the sealer won't fail?

THANKS!!!
-Charlie
 
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  #2  
Old 06-13-13, 12:25 PM
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Are you on relatively flat ground or a hill? Since you don't see drain pipe entering the pit I would look for any foundation drain to be exiting to daylight if you have enough fall on your property. If not I bet you don't have a perimeter foundation drain.

I don't know about the codes in your part of the country but there are still areas today that don't require building inspections or that work be done to any code. It's mostly just up to the builder. Earlier this year in my county a person retired that started when building codes began so prior to about 30 years ago we did not have any here.

Does the pit look like a later addition? Is the concrete around the top of the pit different looking than the rest of the floor? If so I suspect someone added the pit to try and address the water problem. In any case I'm betting there is no vapor barrier under the concrete so even though you don't have water running into the pit there is enough under the slab evaporating and traveling up through the slab.
 
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Old 06-13-13, 01:31 PM
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We are on a bit of a hill, but I don't see any drainage lines exiting to daylight on our property.

From what I can see without pulling up the stick-on vinyl tile it looks like the pit may have been added as there is a little bit darker concrete surrounding the pit.

So assume that we have no tile lines inside or outside the foundation. Lovely.

I suppose the best solution is to install perforated drain pipe inside the perimeter of the footing underneath the slab and run it all into the sump pit or dig up the foundation and install tile lines on the outside. My impressions are that the interior drainage systems are a bit more cost effective and would be more appropriate in my situation if I'm trying to reduce hydrostatic pressure?

Is there another option for me, like sealing the slab or installing a raised floor and moisture barrier like Platon or Dricore? The concrete remains dry (i.e. it evaporates fast enough not to feel damp) as long as it isn't sealed off, so would Dricore/Platon be a feasible option? How could I tell if a sealer like this would work? It says it resists up to 12 PSI, but I have no idea what the hydrostatic pressure in the slab currently is.

Another option I just found is this: Bone Dry Sealer
From their page:
"Bone Dry is formulated to perform against below grade hydrostatic pressure and is also excellent as an on grade moisture barrier and will seal against hydrostatic pressure; however, flowing water must be stopped before application.It seals against seepage below grade (i.e. from hydrostatic pressure)"

It seems reasonably priced given their high expectations, has anyone used this before?
 

Last edited by cwarwick; 06-13-13 at 02:54 PM. Reason: Additional information
  #4  
Old 06-13-13, 02:50 PM
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I do have a perimeter drain tile although having just a crawlspace the drain is not all that deep. I definitely live on a hill but the drain tile does not drain to daylight. I have a downspout drain independent of the drain tile (maybe more than one) that drains into a gully some ten-fifteen feet lower than my house but that is not the perimeter drain.

What I DO have is a storm sewer system and THAT is where the perimeter drain is connected. Exactly how or where I have no idea. So just because you can't see any outlet for a perimeter drain doesn't necessarily mean there is no perimeter drain.

Where does the sump pump discharge water go?
 
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Old 06-13-13, 03:52 PM
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Interesting, I think our street may have storm sewers so that is possible. I wonder if I can confirm that somehow. Although, even if I did have them they're effectively moot since they aren't doing their job right now anyway, possibly clogged or crushed?

The sump-pump exits through the band joist and dumps ~10 ft away from the foundation.
 
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Old 06-13-13, 04:48 PM
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If you can get the official plat of the property (often part of the Title Insurance policy) it might show the storm sewer and if you are really lucky, the point where the perimeter drain connects. Sometimes you can access this through the website of the county assessor or the storm water utility.

It might also be that your sump pump is merely recycling the water from the sump to the ground where it percolates back into the sump to be recycled. Then again, if the pump isn't running and the sump is dry that shoots that idea all to heck.
 
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Old 06-13-13, 05:16 PM
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I doubt it's recycling water, I've never seen standing water in the pit, and I don't hear it run.

Is this what you're referring to?
Iowa City
 
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Old 06-13-13, 05:21 PM
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Yes, that is what I was referring to. Unfortunately it doesn't show the routing of the utilities on yours as it does mine.

That's all I have, sorry I couldn't have helped.
 
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Old 06-14-13, 12:04 PM
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I've been in contact with a few people at various companies and I'm considering applying a silicate based sealer to the floor in order to block moisture penetration of the concrete slab. It'd be ~$150 and if it works it'd save a fair amount of money and effort and I could do it this weekend if I wanted. They claim it should be sealed enough to put vinyl flooring directly on the slab. It seems like a really cheap band-aid fix for a serious(ly expensive) problem.
 
 

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