Basement Waterproofing Options Explained

Wet basements are common in older homes across New York, Pennsylvania, Ohio, Michigan and the rest of the Northeast and Midwest. The right fix depends on where the water is coming from, so diagnose before you spend.

Step 1: Find the source

Condensation

Humid summer air meets cool basement walls and leaves them damp. Tape a square of plastic wrap to the wall for two days. Moisture on the room side means condensation; on the wall side means water coming through.

Surface water

Rain and snowmelt that pool against the foundation because of clogged gutters, short downspouts or soil sloping toward the house.

Groundwater

A high water table pushes water up through the floor or where the floor meets the walls (hydrostatic pressure).

Fixes from simplest to biggest

Outside the house

• Clean gutters and extend downspouts several feet from the foundation.
• Regrade soil to slope away from the house.
• Seal window wells and add covers.

These cheap steps fix a surprising number of wet basements.

Condensation

• Run a dehumidifier sized for the space.
• Insulate cold water pipes.
• Vent the dryer outside.

Crack injection

Polyurethane or epoxy injection seals leaking cracks in poured concrete walls.

Interior drain and sump pump

A drain channel along the inside of the footing collects water and sends it to a sump pump that pumps it out. It is the most common solution for groundwater and avoids digging outside.

Exterior waterproofing

Excavating around the foundation to apply a waterproof membrane and install a footing drain. Most thorough, most disruptive and usually most costly.

About waterproof paint

Waterproofing paints can help with minor dampness, but they do not hold back water under pressure and may peel.

Protect your sump pump

• Test it before the wet season by pouring water into the pit.
• Add a battery backup; storms that cause flooding often cut power.
• Consider a water alarm.

Frequently asked questions

Is a damp basement dangerous?

Ongoing moisture can lead to mold and damage to wood, drywall and stored items. Fix it early.

Should I finish my basement before waterproofing?

No. Solve the water problem first, or new walls and flooring will be ruined.

Post your basement waterproofing job with photos and get bids from local pros.