How to Make Sure Your Basement is Watertight Before Finishing or Remodeling

Finishing a basement adds valuable living space to your home, but before you dive into daydreams of ping pong tournaments and movie screening nights, it’s important to make sure your basement is watertight. Ignoring this step can lead to mold, structural damage, and costly repairs. Here’s a step-by-step guide to checking your basement for water issues before starting your remodel.

1. Inspect the Exterior Drainage

Start by looking outside. Water problems in basements often start with poor exterior drainage. Take some time during and after a heavy rainstorm to walk your property and check the items below.

• Check your gutters and downspouts: Make sure gutters are clean and that downspouts extend at least 6 feet away from your foundation.

• Slope the ground away from your home: The soil around your foundation should slope downward to carry water away.

2. Look for Signs of Water Inside

Do a careful walk-through of your basement, checking for signs that water has gotten in.

• Water stains: Look for discoloration on walls or floors.

• Efflorescence: A white, chalky residue on concrete walls indicates water seepage.

• Damp smells: Musty odors are a red flag for hidden moisture.

3. Test for Moisture

Even if you don’t see visible signs of water, you should test for hidden moisture.

• Tape test: Tape a piece of plastic sheeting (about 2 feet square) to the floor or wall. After 24–48 hours, check for condensation on the underside—this means moisture is seeping through.

• Use a moisture meter: A handheld moisture meter can give you quick readings of dampness in concrete and wood.

4. Check Foundation Cracks

Inspect foundation walls and floors for cracks, which can allow water to enter.

• Hairline cracks: Often harmless but should be monitored.

• Wider cracks: More than 1/8-inch wide can indicate structural movement and should be evaluated by a professional.

5. Evaluate Window Wells

If your basement has windows, check the wells around them.

• Clear debris: Leaves and dirt can clog drains, causing water to collect against windows.

• Install covers: Window well covers keep water and debris out.

Address Problems Before Remodeling

Never finish over a damp basement. If you discover leaks or high moisture levels, solve these issues first. Otherwise, you risk trapping moisture behind walls and under flooring, which can quickly lead to mold growth, wood rot, and damage to finishes. Addressing water issues now will save you thousands of dollars in repairs down the road. Common fixes include:

• Extending downspouts: Move roof runoff well away from your foundation.

• Regrading soil: Ensure the ground slopes properly to direct water away.

• Installing a sump pump or interior drain tile system: Actively manage groundwater and prevent flooding.

• Sealing cracks with epoxy or polyurethane injection: Close up pathways where water enters.

• Applying waterproof coatings or sealants to walls: Add an extra barrier to keep moisture out.

• Improving ventilation and dehumidification: Reduce humidity levels to keep the space dry.

Making sure your basement is watertight before finishing is one of the smartest investments you can make. By addressing drainage, cracks, and hidden moisture, you’ll set the stage for a healthy, dry, and long-lasting living space. Taking the time now prevents headaches later—and ensures your remodel is a success.

At Altura Design Build, we’ve seen how important these steps are when helping homeowners prepare their basements for remodeling. Our team works with clients in Castle Rock, Castle Pines, Parker, Lone Tree, and Highlands Ranch to ensure their spaces are ready for a successful finish.