How to Fix Basement Moisture Issues

Water damaged basement
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When you have basement moisture, you know it right away. Basement moisture might be as apparent as watching the waterline slowly working its way up the basement walls. But it often shows itself in forms that are less apparent: musty smells, slimy walls, damp ceilings.

It is impossible to finish your basement without first attacking and eradicating moisture, or at least reducing it. In terms of remodeling, nothing can happen before the moisture issue is addressed. Homebuyers may look askance at homes that have musty, damp basements. Moist basements might be acceptable for storage or for laundry rooms, but rarely for habitation.

Basement moisture is one of those bedeviling problems that might seem impossible to fix. Once you have fixed one source of moisture, another source appears. But there are reliable methods of drying out your basement or at least creating a more dry basement than you already have.

Basement Moisture Is Common

It can be exceedingly difficult to remove 100-percent of the moisture from some basements. You may need to take the pragmatic view and realize that no matter how many measures you take, some moisture may still remain.

With these types of basements, it is more a matter of reducing your moisture problems than completely eliminating them. Basements in some areas run dehumidifiers constantly to pull the moisture from the air before it lands on walls and floors.

Sump pumps, too, are a regular feature of many basements. Having a sump pump often doesn't mean that your basement is seriously flawed; it simply means that you have a basement.

Moisture Develops From Seepage and Condensation

Most homeowners think that basement moisture is the same as basement flooding. While water may seep into your basement from the ground surrounding the basement walls and even under the basement floor, condensation can be equally damaging.

Condensation forms on basement walls: invisible, airborne water droplets that condense on cold surfaces. Since basements tend toward the cooler side, condensation will naturally form.

Keeping the temperature point high enough to ward off condensation is a good tactic when combined with other methods like running a dehumidifier and blocking water access from the exterior.

How and Where to Locate Basement Moisture

The most obvious sign of basement moisture is standing water. But beyond that, learn to look at your basement like a detective and search for other signals such as degrading materials and rust.

  • Peeling paint on the walls (condensation will cause the paint to peel)
  • White, powdery material on brick walls called efflorescence
  • Rotting wood
  • Flaking drywall
  • Rusting water heater, dryer, washer, or other appliance platforms or feet

How to Fix Basement Moisture

Eliminating or mitigating moisture in your basement is usually not a step-by-step process but one of employing a toolkit of targeted measures that will attack most, if not all, of the issues. Generally, you will want to begin outside of the home before you work indoors.

Reduce Seepage Around Basement

  • Regrade soil around foundation walls to prevent water from moving toward the foundation. With a shovel, bank up the soil to the masonry foundation wall, then slope that earth down and away from the house.
  • Direct downspouts far away from basement walls with downspout extensions.
  • Clean gutters to prevent overflowing gutters from flowing next to the foundation wall.
  • Limit the proximity of large bodies of water such as garden ponds. When garden ponds overflow during a hard rain, they may flow toward the home.

Fill Large Cracks in Foundation Walls

Use a product like a hydraulic water-stop compound to fill large foundation holes and cracks. Silicone caulk is not adequate for filling these cracks.

Seal Outside of the Foundation Wall

  1. Trowel about 1/4-inch of surface bonding cement using a straight-edged trowel.
  2. Wait three hours for the cement to dry.
  3. Scribe lines in the bonding cement with a scribing tool or paintbrush cleaner to help the second coat better adhere to the surface.
  4. Apply a second coat of the bonding cement.
  5. Wait 4 days for all coats to fully dry.

Apply a Masonry Waterproofer

Roll and brush on a waterproofing masonry sealer on the inside of the basement, on exposed concrete or masonry walls.

Install a Sump Pump

For major water intrusion, install a sump pump. Installing a sump pump is a major undertaking, requiring the services of a contractor and a licensed electrician.

Your basement floor must be broken up and later re-patched, and plumbing and electrical wiring are also involved. After installation, the sump pump is on-guard 24 hours a day, every day (though it is not running continuously). When the water level in the sump reaches a prescribed point, the pump will turn on and expel the water.