How to Protect Your Basement from Water Damage

When it rains, it pours, and if that rain ends up flooding your basement, it can feel like a mini-lake. If this happens, you might think about calling a contractor to install an expensive interior drainage system to pump out the water and prevent future issues. But before signing that check, it's possible to fix the problem yourself.

Basements getting wet or damp is quite common. The American Society of Home Inspectors estimates that about 60 percent of homes in the U.S. experience wet basements. As you might expect, a wet basement can cause a host of problems, including mold growth. Water can also damage drywall and wooden framing in the home [source: Wagner].

There are several reasons your basement might not stay dry, but the primary issue is typically water infiltrating from rain or snowmelt through leaks in the foundation. It could also be due to a leaking pipe or pipes affected by condensation [source: Energystar.gov]. (We'll discuss how to address this later.)

For now, let's assume that rainwater and melting snow are causing the issue. When it rains or snow melts, water runs off your roof and towards the foundation of your home. Water naturally flows downhill due to gravity, which is a constant physical principle. This results in the saturation of soil around the house and can seep under foundation cracks. Water can also pass through concrete walls.

The first step in resolving the issue is identifying why your basement is flooding. If you notice leaks after heavy rainfall or during the spring thaw, it’s clear: the water is coming from outside [source: familyhandyman.com]. The next task is to pinpoint where the water is entering your basement. Once you identify these factors, the next step is stopping the water flow. We’ll cover how to do that in the following sections.

Redirect the Water

The solution to a leaky basement is to divert the water away from the foundation of your house. Gutters play a crucial role in this. They collect rainwater and channel it through downspouts. If your home doesn’t have gutters, consider installing them. Also, it’s essential to attach horizontal drain extensions that are at least 4 feet (1.2 meters) long to the downspouts. These extensions will move the water away from the foundation and basement [source: familyhandyman.com].

If gutters are already in place, make sure to clean them. They won't function effectively if they're clogged with leaves and debris. Pay special attention to the area where the gutters connect to the downspouts. If blocked, the rainwater will flow over and cascade straight down to the foundation like a mini Niagara Falls [source: Brasler].

Another method to redirect water away from your home’s foundation is by regrading the ground around it. This process goes beyond simply adding gutters and downspouts but can provide significant benefits. The ground should slope at least 6 feet (1.8 meters) wide, with a drop of about 4 inches (10 centimeters) away from the foundation. To further protect it, you can cover the slope with plastic sheeting, then conceal it with dirt, or top it off with mulch or stones [source: familyhandyman.com].

Seal Leaks and Waterproof Walls

Sealing leaks in your foundation may not stop all the water from entering your basement, but it’s definitely worth trying. For this, you'll need hydraulic cement. This type of cement effectively blocks water coming through the walls. It sets and hardens quickly, so be prepared to use it within 10 to 15 minutes after mixing.

Start by cleaning the foundation surface. Any dirt, dust, or oil will prevent the cement from bonding. Wire brushes are very effective for this task [source: Rodriguez]. After that, remove all loose debris from the foundation, regardless of its size. Then, apply the cement using a trowel.

Waterproofing your walls is another option. It applies like paint, but be sure not to apply it too thinly. The goal is to coat the walls enough for the waterproofing to penetrate the pores and cracks. Also, use a back-and-forth motion when brushing, like the Karate Kid: wax on, wax off. This will ensure it reaches all the necessary spots. As always, clean the walls first with the wire brush. Once the first layer dries, apply a second one [source: familyhandyman.com].

You can also apply a tar or asphalt-like substance to damp proof the exterior wall of your foundation. If your house is relatively new, it’s likely that the foundation is already damp proofed. However, remember that damp proofing won’t last forever. Also, it's important to note that damp proofing and waterproofing are two different things. Damp proofing helps prevent soil moisture from entering your basement, which is often the cause of that musty smell [source: Basement Systems].

Foundation waterproofing membranes are another option, but this method can be costly and is best handled by professionals. These membranes, made from rubberized asphalt bonded to a waterproof polyethylene film, need to be applied to the exterior of the foundation. They are most effective in full basements rather than crawl spaces [source: Home Advisor].

Managing Condensation and Humidity

As previously discussed, condensation and humidity are common culprits for a damp basement. Condensation happens when cold pipes come into contact with warm air. Don't believe it? Just visit your basement on a humid day and watch the water drip from the pipes onto the floor.

To prevent condensation from forming, you can install foam pipe insulation around your pipes. It's inexpensive and simple to install. The foam comes with a slit down the length, allowing you to slide it onto the pipes easily. Trim any excess with scissors or a utility knife. For those in colder climates, the insulation will also help keep pipes from freezing during the winter.

Another way to combat condensation is by insulating your basement walls. Foam tongue-and-groove insulation panels are easy to install and don’t require professional expertise. However, be cautious: avoid installing insulation where water is leaking in, as it will only create an environment for mold to thrive [source: familyhandyman.com].

Humidity can be a challenge, especially on humid days, but you can lower the humidity levels by using a dehumidifier. Some models require manual draining when they fill up, but others offer the convenience of connecting a hose to a floor drain. Additionally, ensure the exhaust line from your dryer is properly sealed with duct tape to prevent excess water vapor from entering your basement.

The most effective way to waterproof your basement is by installing a drainage system. This system includes tubing and a sump pump to move water away. While these systems can be expensive, the cost will vary based on the size of your basement and the complexity of the installation. The process involves breaking up the concrete floor, installing tubing and edging, and then repairing the floor afterward.

It might be a good idea to consult a contractor to discuss possible solutions for keeping your basement dry. There are alternative approaches, beyond those we've mentioned here, that could be a better fit for your particular situation. Ultimately, the most important thing is ensuring that your basement stays dry.