Do you have a leaky basement? Find out everything you need to know about basement waterproofing. Learn how to seal cracks in your basement walls, check for proper drainage, and how to seal your basement walls and floors.

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What You Need for This Project

Inspect Your Home


Check for Cracks in Your Walls

Take a walk around your basement and check for any cracks in the walls. Remember to pull any furniture or décor away from the wall for a thorough assessment.

Check for Proper Drainage in Your Eavestrough & Downspouts

Any improper drainage of your eavestroughs and downspouts can lead to water saturation near your home's foundation, which can cause issues with your foundation and a leaky basement. Foundation repairs can be costly, so it is important that the ground around your house slopes away from your foundation. Look for excessive water spray during rain, and when it is dry, look for eroded earth directly underneath your gutters, or peeling paint on siding or fascia.
Note: If you notice your foundation has a crack in it, contact professionals as soon as possible.

Install Proper Drainage Systems


Unclog Your Downspout & Eavestrough

Carefully remove your downspout and eavestrough. Clean out any debris from the downspout, using a power washer or auger. If there is any damage to the cage, replace the screen.

Install a Downspout Extension

If you notice that your downspout is not long enough, or angled incorrectly for efficient drainage, it is a good idea to add an extension.

  • Measure the diameter of your existing downspout to make sure it is the right size.
  • Stretch out the downspout extension until it is fully extended.
  • Take the side that fits around your existing downspout and slip it around the pipe.
  • Use a gutter elbow to secure it in place.

Repair Any Cracks in Your Basement Walls


Open the Crack

Using a sledge hammer and chisel, open the crack. Undercut the inside of the surface (make the inside of the crack larger than the outside) so that as the hydraulic cement cures, it will expand and become "keyed," or locked, in place in the crack. If you are fixing a crack in a block wall, do not go deeper than ¾ inch or you may burst into the hollow part of the block. Use a brush to clear away any dust and debris.

Mix the Cement

Mix the hydraulic cement as per the instructions on the label. It is important that you have all your tools ready, as hydraulic cement hardens very quickly (about three to five minutes).

Fill the Crack

Dampen the area with a spray bottle. With a trowel, fill the crack with the hydraulic cement to within ½ in. of the surface. After the first layer dries, smooth in a second layer to the right height to match the surface you are repairing. If water is entering through the crack at the time you are making the repair, trowel in the hydraulic cement and hold it in place with the trowel or some other flat surface for five minutes while the cement hardens.

Seal Your Basement Walls & Floors


Clean Basement Walls & Floors

Before you apply any sealant, it is important to clean your basement walls and floors with a mild detergent and stiff brush. Remove any dirt, dust, grease, and loose mortar.

Etch Your Walls

In order for the sealant to stick to your basement walls, you have to etch your walls with an etching compound.

Note: These compounds can be caustic, so follow the directors on the package and make sure you are wearing safety googles and rubber gloves.

Apply Sealant to Walls

Use a sprayer or roller brush to apply the sealant to the walls. Allow the sealant to dry for a couple days before moving on to the next step.

Apply Polyurethane to Floors

If your basement floors have a smooth finish to them, you can apply the polyurethane with a roller brush. If your floors are rough, it is best for you to apply it with a broom. Run the sealant a couple of inches up the walls around the perimeter of the floor to ensure a good seal where the floor and walls meet. Apply three or four coats, recoating according to the product application instructions. Then allow the floor to dry for several days before using it.

Keep Your Basement Dry With a Sump Pump

Stay ahead of flooding with a sump pump. It pumps out water that collects in the sump basin and dispenses it outside.


How To Terms

Tools, products, materials, techniques, building codes, and local regulations change; therefore, Lowe's assumes no liability for omissions, errors, or the outcome of any project. The reader must always exercise reasonable caution, follow current codes and regulations that may apply, and is urged to consult with a licensed professional if in doubt about any procedures.


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