Water entry at basement floor/wall joint

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Old 08-11-08, 07:33 PM
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Water entry at basement floor/wall joint

I am asking for my daughter who is at a complete loss for solutions, and called dad for help. The house is 18 years old, poured concrete foundation and poured cement floor. Lots of rain this year and lo and behold, she has water entering the house where the floor meets the concrete wall on the rear wall. She has removed the wallboard about 6 ft wide now, and vapor barrier and insulation up to a small window, and found no cracks in the wall where water might have come in. She did find water on the floor, between the 2x4 bottom plate and the foundation wall. At times the water makes its way out into the living area. The bottom plate is beginning to be moldy and will need to be replaced. There is evidence of efflorescence as well. After contacting the municipal inspectors, they advised that the municipal building code for a house that age dictates that there is a weeping drain pipe around the perimeter, and is usually connected to a sump pump. She has a sump pump (on the front wall) but is has not run in years.

A contractor she contacted today, wants to cut the floor at that wall, by first cutting the wall studs at 48" high, then cutting a trench in the basement floor by removing 18" of the floor. He will then dig this out, install 12" of gravel, lay a perforated PVC pipe that slopes and drains the length of the of the room to a 2 cubic foot hole filled with gravel. Then he will cement over all of the floor that he has cut away and the room can be refinished.

My question is, should not the outside wall be dug up and new French drain be installed? New crushed stone be added below the weeping drain pipe, and have that drain slope away from the house into the backyard which is not very big (20 ft. deep) and plagued with an underground spring? Possibly have it drain into a "well" of crushed stone? I also feel that an alternative to digging is that she needs to remove the deck on that rear wall and add soil to ensure that there is an adequate slope away from the foundation to help move rain water away from the foundation.

She has 2 young kids and 2 of the above options can be quite costly, so dad taking up the deck and adding soil to create a slope away from the foundation for better drainage. Am I on the right track here, or must the rear wall be dug up, or is the contractor's approach the best way.
 
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Old 08-11-08, 08:01 PM
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I think your idea is better. I've done a lot of wateproofing jobs as part of a crew, and we always did it from the outside.

We would dig a few inches below the footing as wide as necessary, dry the wall with a torch and paste a membrane that came on a roll along the wall. We would let the membrane overlap the footing on to the dirt. It looked like we were carpeting steps. Then we threw #8 gravel along the bottom and backfilled. Of course, you would correct the drainage before you backfill and pitch it properly.
 
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Old 08-12-08, 10:23 AM
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Lots of rain this year...

She has a sump pump (on the front wall) but is has not run in years.
These may be the most telling clues. Hopefully your daughter has been in the house long enough and has been attentive enough to know how the sump used to run. If it used to run occasionally, and hasn't in years even during a high rain season, there's gotta be a reason. Either the pump isn't working properly or the drain isn't. Is there water in the sump? I don't know how the drains are supposed to be cleared if they get clogged, i.e. repair from outside by trenching or from inside by snaking. Maybe hire a plumber that has one of those fancy cameras to run through the drain to figure out what the condition is on the inside. Since money is a concern, it seems to me that the best option is to find out why the drainage system no longer works and repair it. You need to find out if it can be replaced in a small section or as a whole. Of course no one here can tell you whether interior or exterior drainage is better, because it depends on the finished basement which needs to be demo'd, obstructions around the exterior (landscaping, driveways, sidewalks, etc). Most contractors don't want to fix someone elses work, which is why they would rather redo it. That's probably the be all solution, but with a lot of sweat there's a chance it could be done on the cheap once you identify why the existing system stopped working. Unfortunately I suspect many times these intricate systems are created but aren't given enough protection to keep dirt out of the drains.
 
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Old 08-12-08, 10:29 AM
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Old 08-12-08, 06:41 PM
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Thanks to all who have replied. I feel it is better to correct the problem than to apply a "band-aid" by cutting in a drain inside the house. Digging a trench down to below the footing is no easy task, especially being mindful of a possible cave in while digging down so deep. I investigated a plumber with a camera to look inside the weeping pipe and they want $550 to do this. Hmmm. that may prevent a big dig, but maybe the drain needs to be dug up anyway. What to do?? I suggested to her, after reading the link provided, that we concentrate on improving the slope of the land near the foundation, and extend the downspout further away from the house and wait for the next big rainstorm to see what happens. If she still gets water in after that, then digging up the rear wall and improving the weeping drain pipe would be next. I like the idea of a water proof membrane to below the footings on a bed of crushed stone. I can only hope it doesn't come to that. Thanks again.
 
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Old 08-12-08, 07:54 PM
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With 5 or 6 guys, you can reach the footing in 4 hours, install the membrane, throw gravel and backfill in another 4. We used playwood and 2x4s, when we hit 6 feet, to prevent the sides from caving. My boss charged $120 per linear foot.
 
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