How to Waterproof a Basement Before Finishing

by Holly Richards-Purpura | July 19, 2024

Basements are prone to moisture issues, but don’t let water damage go untreated. Waterproofing your basement is essential for keeping your home comfortable, clean, and structurally sound. Here’s what you need to know on how to waterproof a basement before finishing it.  

Signs You Need to Waterproof Your Basement

Some homes are already waterproof and ready for you to finish your basement, but this is not true for all basements. If you notice any of these telltale signs, then you’ll want to implement waterproofing methods for your basement ASAP.

What to Do If Your Basement Is Wet

1. Dry Your Basement

If your basement has standing water or condensation, you’ll first want to clean up the moisture. Do not try to clean your basement if there is standing water around appliances or electricity. Shut off the power to your basement and contact an electrician immediately for water damage around electrical appliances to prevent electrocution. 

For water in other areas of your basement, you can dry the basement using some combination of towels, mops, fans, and a dehumidifier. Opening windows can also help dry the area. However, if your basement gets wet regularly, you’ll need to do more than dry it. With professional help, you can implement professional, permanent waterproofing solutions.

2. Clean the Basement

Once you’ve dried your basement, inspect it for signs of mold, mildew, and efflorescence—a salty mineral residue. If you see fungal growth or mineral deposits on your basement floors, walls, or ceiling, check out these tips on how to get rid of them before you waterproof your basement.

How to Remove Efflorescence

Efflorescence prevents waterproofing paint from adhering to the surface of concrete, so you’ll want to pay special attention to removing it. Apply an etch solution to efflorescence to help remove the residue before scraping or scrubbing away efflorescence with a wire brush or a paint scraper.

3. Remove Old Pain or Sealants

If your basement walls already have paint or sealants on them, you’ll need to remove the old coatings before you can waterproof them. To do this, use a wire brush, chemical stripper, or 80-grit sandpaper, working up to 220-grit sandpaper, for a smooth finish. 

Since old paint can contain chemicals and particles, be sure to wear your PPE. In older homes painted before 1978, it’s also a good idea to test for lead paint before you remove old paint. If there’s lead, hire a professional painter to remove it.

4. Repair Your Basement

After you have dried, cleaned, and removed old coatings from your basement, it’s time to repair any holes or cracks. Hydraulic cement is one of the most effective ways to fill cracks and holes in basements to prevent leaks. Apply the cement to any surface for a temporary solution for waterproofing your basement.  

5. Install a Drainage System

If your home has foundation problems, then even the most ambitious indoor waterproofing methods could fall short and lead to water damage. Have one of our pros inspect your home to determine if you need to redirect rainwater away from your foundation to prevent it from seeping into your basement. French drains, drain tiles, and sump pumps are common drainage solutions we offer homeowners.

6. Caulk the Windows and Doors

Don’t forget sneaky cracks around your basement windows and doors. These areas are often overlooked and can easily allow for water to enter your home. To waterproof your basement windows, window wells, and doors, do the following:

• Remove old caulk, spray foam, and weather strips.
• Apply new silicone caulk along the perimeters of your windows.
• Replace worn weather strips and spray foam for a waterproof seal. 

7. Apply a Waterproof Sealer

While they work much better along with other waterproofing methods, a waterproof sealant can provide some help with keeping your walls dry. Once the caulk and hydraulic cement dry, you can apply a waterproof coating to your basement walls. This solution needs to be applied when temperatures are above 50F. Follow these steps to apply a waterproof sealer to your basement:

• Mix the paint thoroughly.
• Apply the sealer to your basement with a 3/4-inch nap roller. 
• Go in with a brush for hard-to-reach areas. 
• Wait a few hours for it to dry.
• Apply a second coat.

DIY vs. Hiring a Pro to Waterproof a Basement

Holly Richards-Purpura

Content Writer

Holly is a Content Writer for Groundworks who has written and edited web content for the foundation services industry for 10 years. With a background in journalism, her passion for the written word runs deep. Holly lives in Columbus, OH, with her husband. Along with educating homeowners, she also has a big heart for the Big Apple.

Resources

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_{The information provided in this article is for general informational purposes only and is subject to change without notice. We make no representations or warranties regarding the accuracy, completeness, or reliability of this information. We are not liable for any discrepancies in costs or specifications, nor for any indirect or consequential loss or damages arising from the use of this information. Always consult a professional for an accurate assessment and quote before proceeding with any home repair projects.}