First, Dry it Up
Diagnose the Water Problem
Get Rid of Excess Humidity
Eliminating the sources of humid air will help dry out your basement. Seal leaky dryer vents with foil tape to prevent unwanted humid air from entering your basement. Don't just use duct tape; it'll eventually fall off. Add a vent fan to your basement bathroom and make sure your family turns it on during showers. Keep your basement windows closed during humid weather. And if you're still getting condensation on cool surfaces, run a dehumidifier to lower the indoor humidity.
Insulate Pipes
Condensation dripping from cold pipes can contribute to basement water problems. Cover cold water pipes with foam pipe insulation to stop condensation. The foam insulation is inexpensive and easy to cut with scissors.
Insulate Walls
Keep Water Away From the Foundation
If your basement leaks after heavy rains or after snow melts, making sure water is diverted away from your foundation may solve the problem. It's common for the soil alongside your house to settle over time, creating a moat that collects runoff and directs it down your foundation wall and into the basement. Lawn edging and gravel along the foundation can make things worse. Solve the problem by creating a 6-ft.-wide slope that drops about 4 in. away from the foundation. For extra insurance, cover the sloping soil with a layer of 6-mil poly. Then hide the poly with mulch, gravel or a layer of soil covered with grass. This will keep water from soaking in near the foundation.
Add Gutters and Extend Downspouts
Plug Holes and Cracks in the Foundation
Waterproof the Walls
Install a Drainage System
The best permanent fix for chronic basement leaks is to install drainage tubing below the basement floor that's connected to a sump basket and pump. You can install a system like this yourself, but breaking out the concrete floor, burying the tubing, and patching the floor is a lot of backbreaking work. Materials to do an average basement will cost $600 to $1,000. Expect to spend $3,000 to $8,000 for a professionally installed system in a standard-size basement.