Finished Basement Wall Leaking

Have you started to notice that you might have a possible water leak in your basement that’s coming from behind the drywall? As a homeowner, this is one headache that I had to deal with, and I would like to share with you the information that helped me.

The most common reason for a water leak behind the wall of a finished basement is because of a crack in the poured concrete foundation. Luckily, this is often something that you can fix yourself without having to tear your basement apart if you catch it soon enough.

In a basement with wallpaper or wooden paneling, the homeowner might not even know that they have a water leak until it has caused a significant amount of damage. If you can see moisture or mold seeping through the drywall, you should carefully cut out and remove that section of drywall using the proper personal protection to deal with mold.

crack in wall leaking

What Causes Water to Leak From Behind Drywall?

There are a few different reasons why there might be a leak behind your drywall, and I’ll go over those reasons below:

Water pooling around the foundation outside

water pooling outside around foundation

Water pooling around the foundation could cause some serious problems for the homeowner if the basement is not properly waterproofed. Some of the most common causes for water to pool around the foundation is from a heavy rainstorm, melting snow, window well blockage, dripping outdoor faucet, sump pump or downspout not draining fair enough away from home, or a clogged rain gutter that is overflowing.

Water that is pooling around the foundation will seep into the soil and travel down the wall. Because concrete tends to crack, water will find those cracks and use them as an entry point into the basement.

Your best defense is to ensure that water is always draining away from your house and never getting pooled or dumped right next to it.

Leaky pipes

pipe inside wall leaking

A leaky supply pipe or drain pipe behind the wall could cause a lot of damage in a short period. Often, the only way to know that you have a leaky pipe is because you can see damp, wet spots on the drywall or carpet.

If you bought the house and the previous owner had already finished the basement, you might not even be aware of it, but they could have installed drywall overtop of some old water pipes that are starting to corrode and leak. Another common reason for pipes to leak is because of a poor plumbing joint or seal.

Concrete Floor

water coming through floor

It is not unusual to have water seep up through a concrete floor that was not properly sealed and waterproofed. When it rains, the ground surrounding your home will absorb that water until it can no longer absorb any more. Once that happens, the water trapped in the ground will begin to rise back up causing what is called Hydrostatic Pressure. Hydrostatic pressure builds up against your foundation walls and floor, which causes water to seep into your home through the cracks in the concrete.

Sometimes what you might think is a leak from behind the wall, is water that is coming up through the floor. Before laying out your flooring or carpeting, you should always make sure that your concrete floor is properly sealed and waterproofed to avoid water seepage.

So, if you are noticing a wet spot in the carpet or along the bottom of the wall, the source of the problem might be underneath your feet.

How to Find The Source of a Leak in a Finished Basement

Generally, it’s much easier to locate the source of a leak in an unfinished basement because you’ll be able to visually see cracks in the concrete, or pipes that are dripping. Trying to locate the source of a leak in a finished basement, on the other hand, is a little more tricky. Often, the source of the leak is not even where you might suspect, so locating where the leak is coming from could become a bit of a guessing game.

There are tools available such as a digital moisture meter that will detect moisture content in drywall and wood. You can pick one of these tools up from your local hardware store or Amazon relatively cheap. This tool won’t tell you where the leak is coming from; it will only help pinpoint where the moisture in the drywall is too help narrow down your search.

Here are a few things that you could do to help determine where the source of the leak might be coming from.

1. Look for cracks

look for cracks outside on foundation

Before you start ripping drywall off, first take a walk around the exterior of the home in the general area where the leak was visible on the inside.  You want to inspect the above ground wall for any visible cracks, holes or other signs of damage in the poured concrete foundation.

If you are not able to see any cracks, or the earth is covering the wall, then dig down a couple of feet in that general area where you suspect the problem to be located. Use a wire brush to scrub away dirt clinging to the concrete as you dig down. You are looking for cracks that are generally vertical and narrow.

2. Turn off all water supplies

look for cracks outside on foundation

If you are unable to spot a crack in the concrete wall, you could try turning off all of the water supplies throughout the house, such as faucets and appliances that use water. After, take note of the number on the water meter. Wait three to four hours and check that number again. If the number has moved then you know that the problem is coming from a water pipe, possibly located behind the wall.

You could also have a plumber come by to try running a hydrostatic test on the homes water supply as well as the sanitary sewer system.

3. It might be time to cut a hole

cut hole in wall

If you can not locate the problem, you will need to cut a hole in the drywall to look for the source. Nine times out of ten, if the leak is not due to a crack in the poured concrete, then it’s a leaky pipe.

Start by cutting a small one foot by one-foot hole in the center of where you noticed the water damage. Hopefully, the hole will be big enough to detect a leaky pipe or whatever is causing the water. If the hole is not big enough, you can slowly make the hole a little larger until you can find the source.

If it is a pipe leak, you should contact a professional plumber and have them come out to repair the pipe for you.

How to Stop Water Leakage From Wall

Ideally, if you have a finished basement, you will want to avoid tearing drywall and everything else apart to get to the problem. Instead, the best way to stop the leak is to do the repairs on the outside. To do so, you would have to excavate down alongside the wall about a foot or so past where the crack or cracks stop.

  • Use a metal brush and some water to clean the dirt off the wall.
  • Use a chisel or grinding saw to open the crack up a little more.
  • Use an epoxy or urethane resin to inject the cracks. That will help seal the crack from top to bottom inside of the wall.
  • Use a Hydraulic Cement to now cover the entire crack a few inches on either side to ensure it’s sealed nicely.
  • Apply an Aqua Bloc application over the repair, and about a foot past in all directions.
  • Lay a strip of Yellow Jacket Installation over everything, and apply more Aqua Bloc overtop to seal it nice and tight.
  • Next, lay a strip of plastic over the entire repair area, and apply one last coat of Aqua Bloc to attach the plastic to the wall.
  • Last, lay a strip of Delta Wrap about a foot wide down the whole length of the repaired area for some extra protection.

patch outside crack in foundation

Wait an hour or two to give it all a chance to dry, before you begin adding dirt back into the hole. Compress the dirt every one and a half to two feet as you fill in the hole.

If the crack looks large or covers a sizable area of the wall, you should give a professional a call and have them come out to take a look at the problem. The problem might be much bigger then you can handle.

How to Prevent Future Water Leakage Problems

downspout draining away from foundationThe best way to prevent any future water leakage problems is to make sure that you have the proper drainage set up. Your downspout and sump pump discharge pipe should be draining at least six to eight feet away from your home. Rain gutters should be cleaned and cleared occasionally to avoid having them clog up with dirt and leaves.

Ensure that the earth surrounding your foundation is elevated slightly higher to allow water to run down and away from your home. If you notice any places where water is pooling, you should quickly look at how you can get it to drain away. For those of you who have a below ground window, you should regularly inspect the window well to ensure that it’s not full of leaves, garbage or other types of debris, so water does not pool up inside of it.


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