Damp refinished basement

9 Replies

The ground floor of my duplex apartment is below-grade and has experienced water infiltration. I only recently bought the property and have repaired the leaks I can identify, but one appears to be coming from the outside entryway of a neighboring attached building - essentially, the entryway is badly graded, causing water to pond in the area where the building meets mine and penetrate my basement. It's uncertain whether this area will be repaired and I'm looking for alternative solutions, like waterproofing the party wall from inside my basement. Has anyone done this before? What were the results? Thanks.

Stopping water from the inside that is penetrating the concrete/block is very difficult. It's more realistic to "cede some ground to the enemy", so to speak, and pick a defensible position. From the inside, this usually means something like a perimeter drain, piped to a sump pit and pumped into a sanitary sewer (if allowed) or far away from the house to a daylight drain. The best way to accomplish this (in my opinion) is a perimeter cut all the way around the floor slab, perf pipe and gravel to a sump pit. Then you box the cut and finish the walls as desired, or false-wall it in front of the cut all the way around, and there's your finished basement. 

If you don't want to go that route, there are waterproofing membranes that you can apply to interior concrete/block, but keep in mind the hydrostatic pressure of water in the ground can be tremendous and will eventually find the weak spots of this approach. 

Based on your problem, if this was my house, I would add some surface drainage to move most of the ponding water to another location first. That would be far cheaper and solving the water problem from the outside is 90% of the battle with wet basements, assuming water is not bleeding through the floor from a high water table. 

Thanks JD, I appreciate the quick feedback. Agreed that it would be better (and likely much less expensive) to tackle from the outside, but it's good to know the options for dealing with the issue on the interior. Appreciate it.

If I may add, Never by no means ever waterproof or try and correct the issue with interior drainage systems, think about it your still allowing moisture in the basement, if anything now your increasing moisture from entering into the dwelling because now you just exposed below the foundation floor, its a cheap way of putting a i guess you can say band aid on a more serious issue. Its an incorrect way to resolve a problem. Ive done many foundation water proofing jobs where contractors came in and did perimeter drains, to only call me in years later to do what should of been done from the beginning.  Always correct the issue from out side.

1st how old is the house, you say the walls are damp, well do you have gutters on all the roof lines, you be surprised how many damp basements get fixed by cleaning your gutters or making adjustments, where are the gutters dumping? are they dumping at the foundation or piped away from the house? If you were getting moisture through the floor then I would suspect footing drains need to be replaced or may need sump pump. Many different variables but id start with the gutters, next id check is whats the grade of the yard, is there any surface pitched towards the house, is there a patio, you'd be surprised how many contractors don't know how to use a level when installing a patio

Michael Gessner, Contractor

My apology i miss read, so you know where the water is coming from, if the grade is pitched towards you, the grade needs to be corrected, if your gutters are also dumping in a location where it will increase the water coming in they need to be corrected as well

Michael Gessner, Contractor

Thanks, Michael. One leak did come from the gutters, which I fixed. I'd like to address the grading issue but it will mean accessing the neighboring property. Owner has not been responsive thus far.

Thanks. I'll be up there this week and can send some pix.

Ok keep me posted, if its a finished basement it might be worth your time and expense to rectify the issue out of your pocket. the problem with people finishing basements is once you close up those walls, by the time you start seeing mold on the surface of the drywall its most likely to the point you will be gutting it. I tell all my customers who want to finish the basement to make sure its dry and any drainage issues are corrected before hand. Just a bit of advice. The neighbor probably doesn't want to deal with the expense if its a large enough area, however depending on where you sill plate is compared to finish grade, you may be able to simply add soil to your side and channel the water away. Any how get me some pics id be glad to give you some advise. 

Michael Gessner, Contractor

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