How to waterproof a basement
Home Safety Tips Resources » How To Waterproof A Basement

How to prevent a wet basement

If you live with wet weather, even if you’re not living on a flood plain, your basement can get soggy. According to iPropertymanagement.com, 98 percent of basements will eventually be damaged by water, and the average insurance claim for that damage will be over $11,000. Nationwide, this adds up to $20 billion each year.

The cost goes beyond mitigation and repair, though. Wet basements look, smell, and feel unpleasant, and if they aren’t addressed, they can also erode your home’s value.

What’s a property owner to do? Here are some reasons why basements develop water problems, plus strategies for staving them off.

WHY WET BASEMENTS HAPPEN

Basements get wet for lots of reasons, and sometimes for several reasons simultaneously. Most commonly, it’s because a house’s foundation was excavated at depths below the local water table, causing groundwater to flow into the basement space the way it fills a well. The water table can rise or fall, and any time it rises above the level of your basement’s floor, it will find whatever path it can — often a crack between the wall footings and the basement slab that makes up the floor of the basement — into your house’s interior.

Water can also get in if your downspouts empty too close to the house’s foundation, or if the soil around the house’s perimeter has been improperly graded. And water problems can also develop when a house is built on a hillside’s downward slope.

 

IDEAS FOR BASEMENT WATERPROOFING

Whatever the reason for your house’s wet feet, this is a solvable problem. And it’s a problem you should solve before the damage — foundation stones moved out of position, floors cracked or broken up, mold and rot affecting the house’s structural members — begins to take hold.

  • Consult a contractor. If you already know that keeping your basement dry is going to be a challenge, consider heading it off by having a contractor tackle it. Yes, that can be an expensive proposition, but maybe less than you fear. And it’s better to know what you’re dealing with — based on the advice of a trustworthy pro — than not to know. While foundation repairs can be pricey, there are multiple less expensive ways you can start waterproofing your basement.
  • Check and maintain your downspouts and gutters. A downspout’s job is to carry accumulated water several feet away to a well-drained area. Start by inspecting your gutters, cleaning them out, and repairing any holes. You can also improve the gutters’ function by installing a cap that will keep most debris out of the gutters and improve water flow and discharge. Make sure the gutters are firmly attached to the house and that they slope toward downspouts to allow water to fall directly from the roof to the ground. Reconnect any disconnected downspouts and attach extensions where needed to ensure that water is released a proper distance from your house.
  • Consider a sump pump. An upright (pedestal) or submersible sump pump that’s been properly maintained can be your home’s first line of defense. Inspect and clean any existing pump and test it by pouring water into its pit. The discharge hose should carry the water several feet away from the house to a well-drained area.
  • Foster the foundation. If your inspection reveals that the soil around your foundation is improperly graded, you’ll need to build up the soil around your home’s walls to divert water in the right direction. According to energy.gov, the earth around your house should slope at least 5 inches in the first 10 feet. The grading should consist of fill soil with a clay content of 20 to 30 percent, with free-draining soil as backfill underneath.
  • Watch your window wells. Window wells can allow light into your basement, but they also collect water. Make sure the perimeters of your basement windows are well caulked and sealed to head this off. All entry points need to be inspected, and don’t forget to check for cracks in the surrounding wall or floor where water could seep in.
  • Install water-leak detectors. Knowing when a basement leak has started is half the battle. Many water-leak sensors even connect to your home’s Wi-Fi.
  • Check your insulation. If water has gotten into your insulation, its value is compromised. Weeping moisture on the walls can sometimes indicate that you’re having condensation issues, which might also mean you’ll need to add to or replace the currently ineffective layer of insulation. You may also want to paint your walls with waterproof paint or sealer.
  • Put your snow shovel to work. Most basements get wet when rainwater or melted snow runs toward houses from roofs, yards, and driveways. So, it’s a good idea to move snow away from the foundation of your home. In the winter, pushing it 3 to 5 feet away from the structure to help protect your basement from snowmelt runoff.
  • Use your yard as a sponge. Just getting water away from your house isn’t enough — the true goal is getting the water to soak into the ground and stay there. One way of doing this is planting a rain garden. This uses native shrubs, perennials, flowers, and grasses to collect and sequester water from hard surfaces such as rooftops, sidewalks, driveways, and patios, holding it so it can slowly soak back into the ground. Not only will this help you in your fight to keep your basement dry, the rain garden’s plants, mulch, and soil will naturally remove pollutants from the runoff, as well as providing habitat for pollinators, songbirds, and other wildlife.

The Federal Emergency Management Agency (FEMA) shows the top five ways to prevent basement flooding in this quick video:

 

STILL AT RISK?

Sometimes the water flows where it wants to flow despite your best efforts to redirect it. If the worst happens, here are a few things you should put at the top of your disaster to-do list:

  • Assume the water is dangerous. It’s safest to conclude that any water pooling in your basement is unsanitary and potentially toxic. If you’re determined to make your way into your flooded basement space anyway, make sure you wear boots, gloves, and even a mask — particularly if the cause of the flood is a sewage backup. This might be an area where it’s safest to leave diagnosis and repairs to plumbing experts.
  • Call the utility company. A flooded basement is a terrible place to find out about a shorted junction box or a submerged electrical socket. In such a case, the power will obviously need to be cut, but you should — once again — leave that to the professionals.
  • Find a better place for your valuables. The basement is a bad location to store irreplaceable or sentimental items such as photographs and important documents. Consider putting these items someplace you know will stay dry. If you absolutely must put your valuables downstairs, invest in some plastic shelving units and airtight plastic totes.

Sources: PennState Extension; Forbes.com

The information included here was obtained from sources believed to be reliable, however Grinnell Mutual Reinsurance Company and its employees make no guarantee of results and assume no liability in connection with any training, materials, suggestions, or information provided. It is the user’s responsibility to confirm compliance with any applicable local, state, or federal regulations. Information obtained from or via Grinnell Mutual Reinsurance Company should not be used as the basis for legal advice and should be confirmed with alternative sources.

Updated 07/2024