What’s the water source

If your basement smells musty, looks moldy, or sports little puddles after every rain, you’ve got a wet basement problem. Long-term dampness will damage trim and finishes, and erode framing and foundations—problems that would cost thousands to fix. In addition, damp basements promote mold and mildew, which can harm your health.

Moisture in a wet basement comes from three main sources:

  • Groundwater: Lives within pockets beneath the earth’s surface; can seep through unsealed concrete slabs, form puddles, or just cause that wet basement feel.
  • Precipitation: Rain, snow, sleet, and melted hail that flow into basements under doors or through poorly sealed windows.
  • Hydrostatic pressure: Water-soaked soil that pushes moisture through walls and floors and produces a wet basement.

Fix a wet basement’s water woes

The best way to stop water flow into your basement is to solve the root cause. Sometimes the solution is easy, like extending downspouts or grading property so water runs away from your house.

Sometimes it’s harder to fix wet basement problems.

If your wet basement is caused by hydrostatic pressure, excavate around the foundation’s perimeter and install a drainage system and waterproofing membrane. These reduce pressure against the structure and blocks water from seeping through the walls and causing a wet basement. A professional can do the job for $5,000 or more.

If you can’t afford the outside-in water treatment for your wet basement, solve the problem from the inside out. Working from inside your basement, cover all foundation cracks, framing joints, and floors with a brush-on, waterproofing sealant. This DIY project typically costs $1,700 for a 20-by-30-foot basement.

Sump pumps to the rescue

A sump pump, which removes water from a sump pit in the ground, is your best defense against seeping groundwater or minor floods. (If major floods are frequent problems, don’t finish your basement.)

When the sump pit fills, the pump automatically engages and shoots water into drains or other areas that flow away from the house. Professional installation, including wiring to a dedicated circuit, costs $2,000 to $6,000. Always keep a battery-powered, backup pump around ($300) in case the power goes out during a storm.