Basement Waterproofing and How it Works
If you’re trying to figure out how to fix a wet or stale basement, you’re likely curious about promotions for products that claim to waterproof basement walls. So you wonder, Is it possible to dry out a basement merely by sealing the walls?
Yes, it is achievable — but to make sure you’re selecting the right option, you need to figure out if the moisture is coming from the outside or if high humidity is condensing on the cool walls of your basement.
How to Find Out What’s Inducing the Moisture in Your Basement
Tape a 1-foot-square piece of aluminum foil to the inside of your basement walls and leave it in place for 24 hours.
If there’s condensation on the outside of the foil, you have high humidity in your basement. Correct it with a portable room dehumidifier or a whole-house humidifier system instead of waterproofing products.
If the foil has condensation on the inside surface (next to the wall), the soil around your house may be naturally moist from a high water table or poor soil drainage. In that case, waterproofing your basement walls can be helpful.
You can waterproof just your interior walls, which may crack the problem. Or you can waterproof your exterior walls, which is a more suitable bet — but more costly.
Here’s the scoop on the various types:
3 Types of Interior Waterproofing for Your Basement
Concrete Waterproofing Coatings
These thick coatings are cement-like. Once they dry, they stick permanently to concrete and masonry walls. You spread the coating with a heavy brush made with tampico bristles — a natural fiber. Swirl the brush at the final application stage to give the wall an appealing, finished look. Concrete waterproof coatings can’t be used on previously painted surfaces; check the label.
Silicate-Based Concrete Sealers
Also known as densifiers, they are appropriate only for walls that haven’t been painted or sealed. The sealers soak in and chemically respond with ingredients in the concrete or brick, forming a hard, waterproof surface. Because these are penetrating sealers, they can’t flake off or peel, and you can paint over them (but check the label first). Laying a silicate-based sealer with a brush, roller, or sprayer is manageable enough for a DIY project.
Waterproofing Paint Is an Acrylic Formula
It's not all that different from regular wall paint. But you brush, roll, or spray it on much more thickly. Waterproof paint is acceptable for DIY applications. You can apply it over painted surfaces and paint over it once it’s cured.
Exterior waterproofing implicates excavating all around the house to the full depth of the foundation walls and then installing a waterproof coating or membrane topped by drainage panels. The panels provide an easy path for water to stream down to an exterior French drain at the footing of your foundation. From there, water flows by gravity — or with a sump pump — away from your foundation to another part of your property or into a storm drain.