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How to Cure a Wet Basement

4 Steps to fixing a leaky basement. The basic solution is often the best solution.

FH09APR_497_06_039-2Family Handyman

Water in your basement? Don't call the basement waterproofing company yet. According to our expert, many basement leaks can be cured with a weekend's work and a few hundred dollars' worth of dirt and plastic.

We talked to Robert Vassallo, owner of Complete Building Solutions, an engineering firm that specializes in solving water-related building problems. His firm takes on many complicated wet basement jobs, but he was quick to point out that a huge percentage of wet basements can be remedied by simply regrading the landscape, and adding or upgrading gutters and downspouts. The graphic at right shows the key elements for an effective solution.

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4 Steps to fixing a leaky basement

The basic solution is often the best solution.

Of course, this fix will work only if the water entering your basement is coming from rain or melting snow. But it’s pretty easy to tell. If you get water in your basement shortly after a storm, or when the snow is melting, or if a wet inverted-V pattern appears on the wall, the cause is most likely improper grading or a downspout that’s emptying water near your foundation. And even if there are other factors contributing to the wet mess, the basement waterproofing solutions we show here will help keep your basement dry and should be done before you take more extreme measures.

1. Check the landscape around your house

Inspect and take notes

You’ll need to do a thorough check of the ground around your foundation. For this you’ll need a 4-ft. level, a tape measure and a notepad. First draw a simple sketch of your house and yard on your notepad. Then use the level to check the slope of the ground around your foundation. Look for areas of sunken soil, garden beds with edging that protrudes to form a dam, and ground that slopes toward the house. Make notes on your sketch with arrows to show which way the ground slopes. This step will help you develop a plan for redirecting the water away from the foundation.

2. Make a plan and order material

What You’ll Need

  • Compactable fill
  • 6-mil poly
  • Edging
  • Mulch or gravel

With the sketch in hand, you can figure out where the problem areas are and what you need to do to fix them. The goal is to create a 6-ft.-wide perimeter that slopes away from the house. Aim for a slope of about 1 in. per foot, but if this isn’t practical, get as close to it as you can. There are two ways to change the slope of the ground near your foundation. You can add soil or some other compactable fill near the house, or you can move soil from the high area to the foundation. In either case, keep in mind that you should maintain 6 in. between the soil surface and the siding to prevent rot and discourage insects.

If you need a lot of fill, it may be cheaper to have a dump truck deliver a load. Otherwise you can buy bags of soil at most landscape supply stores or home centers. You’ll also need enough 6-mil black poly sheeting to cover the area between the foundation and 6 ft. out. And if you like our idea of using bricks for the edging as shown in the illustration, you’ll need to order these too. Finally, you’ll need some mulch or other decorative material to cover the poly.

3. Create the slope

Use a tampling tool or power tamper

Compact the fill and create a smooth, hard surface.

If you have shrubs or trees near the foundation, they may be part of the problem. In some cases, their roots form a channel for water to reach the foundation, or they penetrate cracks in the foundation and create new paths for water to enter. Remove shrubs and trees that you don’t need. You’ll have to work around any that are a valued part of your landscape.

Next, spread the new fill, using a level to check the slope. Or simply regrade the soil near your foundation to create the slope. Use a garden rake to smooth and level the ground. When you’re happy with the slope, tamp the soil to compact it. If you’re doing the entire perimeter, it may be worth renting a gas-powered tamper for this. Otherwise a hand tamper will work.

If your plan includes adding bricks along the edge, dig a trench deep enough so that the top edge of the brick is level with the ground. Then lay 6-mil poly over the ground and into the trench. Finish up by placing the bricks and covering the poly with mulch, wood chips or some type of decorative stone or gravel.

4. Check your gutters and downspouts

Extend your downspouts

If you don’t have gutters and downspouts, consider adding them. Otherwise most of the water from the roof ends up right near the foundation where you don’t want it. If you do have gutters, or if you’re adding them, make sure to attach extensions to the downspouts so that the water discharges at least 6 ft. away from the house.

If at first you don’t succeed

These four simple steps will solve most basement leaks caused by surface water like rain and snow melt. But if your basement still leaks after you’ve made these corrections, consider hiring an engineering firm experienced in solving water leakage problems to propose other remedies.

Be cautious about hiring companies that offer only their own solution, because it may not be the best one for your situation. And if you’re looking for more information on solutions to wet basements, how to deal with wet carpet, how to fix plumbing leaks, or how to add an interior drain and sump pump, search for the key words at familyhandyman.com

Learn From A PRO!

Tips from Robert Vassallo

  • For a premium job, substitute EPDM for the 6-mil poly. Contact local roofers to see if they’re tearing off an old EPDM roof. You may be able to get the material for free.
  • Use ground-up recycled concrete and asphalt for fill. It’s cheap and compacts easily to form a hard, dense surface.
  • If you can’t regrade the entire perimeter, do as much of it as you can.
  • For extra insurance against any water getting in near the foundation, seal the 6-mil plastic or EPDM to the foundation wall with acoustical sealant caulk and install a flashing over the top.
  • Consider building a rain garden if you can’t easily drain water from your yard.

Robert Vassallo is the owner of Complete Building Solutions in Golden Valley, MN. The company specializes in finding solutions to tough water problems in residential and commercial buildings.