Wet Basement Solutions

Answers to Vexing Questions About Your Wet Basement

Water damaged basement
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For many homeowners, a basement isn't just a nice thing to have; it's essential living space. And there is no greater obstacle to homeowners finishing their basements than the looming specter of a wet basement.

A flooded basement will instantly cancel out all of your good finishing work: floors ruined, drywall waterlogged, insulation soaked. But what about a basement that gets wet in certain areas after a hard rain?

Or the basement with mysterious pools of water that seem to come from nowhere?

Here are common problems and solutions for wet basements made of concrete or block.

1. "Is Water Leaking 'Inside the Box?'"

When a homeowner sees water in the basement, the immediate thought is that it is coming through foundation walls. For this reason, it's easy to be blind to internal causes. It pays to "think inside the box"--the house "box," I mean.

Rule out anything in the basement that holds or produces water. Possibilities include:

  • Washing machine.
  • Water heater.
  • Plumbing pipes above head running through floor joists.
  • Basement bathroom sink, toilet, or shower.
  • Wet bar

2. "Is Water Leaking Through a Crack in the Concrete Wall or Block?"

Cracks in the foundation wall are the classic culprit for water leakage in the basement. Not all cracks result in leaks, though. Look for the obvious sign (water) or the not-so-obvious (calcium efflorescence left over after water has evaporated).

How to Fix It:

Counter-intuitive as it seems, you'll need to chip along the crack in order to widen it (to about 3/4") and deepen it (to about 1/2"). This is the only way to get the hydraulic cement to adequately hold in place.

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3. "Is Your Floor Slab Leaking?"

Don't just look up or sideways for leaks--look down, too.

Concrete floor slabs are as prone to cracking and leaking as other areas.  Ground water can seep upward through cracks in your concrete floor slab.

How to Fix It:

Widen and deepen the crack to about 1/4"-1/2 wide and deep. Make sure the edges of the prepared crack do not form a "V" shape; otherwise, your sealant will not properly stick. Instead, chip sides straight down or, better yet, outwards at the bottom (to form a "tomahawk" shape). Fill with elastomeric concrete sealant.

Elastomeric sealant is not the same as silicone or painter's caulk, the type you might use for windows or bathroom sinks.

Elastomeric sticks like crazy to concrete and masonry, and easily shrugs off temperature ranges from -30F up to 100F.

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4. "Is the Joint Between Your Wall and Floor Slab Leaking?"

When it comes to holding back water, any kind of joint spells trouble. Because the wall and floor can move at independent rates, cracks may occur where the two join.

How to Fix It::

Water leaking in this area may be the result of surface water percolating downward. Installing a drainage system may fix this problem. If the crack is less than 1/4", chip away loose areas with your cold chisel and hammer.

Sweep out loose particles. Apply urethane-type elastomeric sealant into the crack.

If the crack is more than 1/4", the mere sealant will not do the trick. Consult a foundation repair company.

5. "Is Water Leaking From Around a Window?"

Windows in basements provide rare natural light in an otherwise dark place. But windows also provide great leakage points for water from the outside trying to get inside.

How to Fix It:

Install a window well liner and window well cover. Dig out a window well and place a liner inside this hole to prevent dirt and moisture from infiltrating the hole. A nice bonus is a window well cover to seal up the entire space.