Basement Waterproofing: Best Methods to Keep Your Basement Dry

A constantly wet basement is a waste of space, a source of mold, possible allergic reactions, and a money pit. Proper basement waterproofing can keep your space dry and prevent future problems.

Keeping or making your basement dry can add to your living area, eliminate mold and odor, and save money. Dry, finished basements increase the value and livability of your house.

Basement waterproof:Best Methods to Keep Your Basement Dry

Basement waterproofing begins outside. Before dealing with the leaking foundation, take care of easier and less expensive issues first. You might solve the problem.

What Causes Wet Basements?

The leading causes of wet basements include improperly sloped soil, swales, drains, landscaping issues, foundation cracks, faulty sump pumps, or humidity problems within your home.

While you can’t stop big rain storms with high winds or snowpacks, there are ways to keep moisture away from the house.

Basement waterproof:Best Methods to Keep Your Basement Dry
US Dept. of Energy
  • Landscaping. You should grade your soil to slope ½” every foot for 10 feet from the house and then tamp it to prevent settling. If space limits you to less than 10 feet, consider a swale or French Drain to carry water away.
  • Gutters and Downspouts. Make sure gutters are installed and sloped properly. Downspout runoffs should be 10’ long to get water far enough away to prevent it from wicking back to the foundation. (Note: Any water within 8’ of the house can reach the base of an 8’ deep foundation.)
  • Swales or French Drains. Ensure swales (shallow dips in the lawn to carry surface water away) and drains are appropriately sloped to move moisture away from the house.
  • Weeping Tile. Weeping tile is not tile but a 4” porous flexible plastic pipe designed to collect and move water away from houses. It goes at the base of basements during construction and is also used in French Drain construction.
  • Window Wells. Window wells collect and hold a lot of water, which can run around windows or through cracks in the concrete. They should have a drain pipe dug down to the weeping tile.
  • Sump Pump. Sump pumps get rid of excess water in the basement, under the floor, or from around the basement. They are supposed to be pumped out of the house to drain on the surface. Sump pumps have been known to back up and become part of the problem.
  • Foundation Cracks. Cracked foundation walls allow external water sitting against the wall to get into your basement.

Basement Waterproofing: Keeping Water in the Yard

Every drop of water kept in the yard is one you don’t have to worry about in the basement. If water seeps into your basement after a rain storm, look at the slope of your soil, window wells, and drainage system.

Get the Proper Slope

Regardless of how much tamping and packing, disturbed soil close to the house will settle. Attach a level to a straight ten foot 2 x 4 and check the slope around your home. Set one end against the house, lift the other until level, and measure the distance to the ground. It should be at least 5 inches. Add dirt to any area needing more slope. Then, pack it and seed it.

Note: Try to achieve your slope without soil covering wood or aluminum siding on the house. Wet topsoil will speed up the rotting of wood. Also, lawn fertilizers can have a chemical reaction with aluminum causing it to melt away.

Enhance the Drainage System

Extend your downpipes to at least 10’. Drain them into trees or shrubs that absorb water. Enhance your system of swales and french drains to move moisture away from the house, so it doesn’t end up in the basement. Make them as simple as possible to do the job. Simple is usually much less expensive than pop-up drains and holding–tanks if it works.

Note: We have a Blind drain (No pipe – just gravel) on three sides of our house and a dry basement in an area of underground springs.

Deeper Window Wells

Many houses are afflicted with dinky window wells incapable of stopping heavy dew. Or someone threw down a couple of 4 x 4s many years ago. Install new window wells that extend at least 2” below the window frame, 2” above ground level, and project 2 feet from the wall. Screw and seal them to the wall with caulking or putty tape.

Add Window Well Covers

Installing window well covers will prevent most rain or snow from getting into the well. Made of clear polycarbonate, they are screwed onto the window well and the wall. Although not completely waterproof, the covers should stop enough moisture to keep water from collecting in the well and leaking through the gaps around window frames.

Note: If your basement windows need to meet egress requirements, secured window well covers do not meet code.

Waterproofing Exterior Basement Walls

Where I live, waterproofing the exterior of basement walls has been code for over 50 years. It is accomplished by spraying the entire wall with a thick coating called polymer-modified asphalt down to the footing and 4” above the final grade.

The tar-like substance fills cracks and form-tie holes and expands and contracts over 1/16”. Some sprays require multiple coats to provide a thicker layer of protection.

Other options include waterproof covering like Blueskin–a peel-and-stick product that adheres to concrete, concrete block, and most anything else it touches. These coverings are also installed from footings to above grade.

Whichever exterior basement waterproofing option you choose will be better than waterproofing from the inside. Hydraulic pressure is the pressure of a liquid against an object. It is always better to continually push the waterproofing towards the wall than away from it–as with interior repairs.

Waterproofing exterior basement walls can cost $15,000.00 or more. While the products can be a little expensive, the greatest cost involves removing the dirt around the basement and replacing it.

Remove the Flower Beds

It is common to plant flowers next to the house. But, keeping them well watered could be causing a basement leaking problem because the foundation wall is wet.

Moving the bed 4 or 5 feet from the house should help keep the basement dry. Large trees and hedges close to the home can cause other problems, but watering them may add to the leakage issue.

Waterproofing Interior Basement Walls

Before deciding which repair you will use, ensure you know where the water is coming from. For instance, if entire walls look and feel wet, you may have a humidity problem, not a leak.

Most basement waterproofing repairs work better when the walls and floor are dry because products adhere better, and dragging electrical cords through water is dangerous.

  • Hydraulic Cement. Hydraulic cement is an excellent product for filling cracks in concrete and replacing mortar in concrete block walls. As hydraulic cement expands, it will push deeper into cracks providing a solid seal between adjoining material. Follow all of the directions and have the patience to mix small batches. It only has about a 3-minute window of working time once mixed.
  • Leaking Windows. Even if you have sealed the window frames from the outside, seal the inside. Remove the casing and spray low-expansion window foam into the gaps and cracks. Replace the casing and caulk the wall.
  • Waterproof Paint. You will find several types of waterproofing concrete paint. It can be rolled on and left to dry. Then apply the second coat. It does NOT adhere to painted surfaces, so remove the old paint first.
  • Sump Pump. Ensure your sump pump is in good operating condition, or consider installing one. You may want to hire a professional.
  • Interior Drainage Systems. Many interior drainage systems are available. They are usually quite expensive–starting around $5000.00 and going up from there.