How to Waterproof a Basement Like a Pro

Deane Biermeier
Written by Deane Biermeier
Updated October 20, 2022
A woman using her laptop in a basement living room
Photo: Morsa Images / DigitalVision / Getty Images

Protect your basement from water damages

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

Moisture, or worse yet, standing water in your basement, is more than just an inconvenience—it’s a sign to learn how to waterproof a basement. A wet basement is unusable as a living space and can harbor harmful mold and mildew. 

Home builders make every effort to keep water from penetrating the foundation during construction. However, over time, soil saturation and cracks from the foundation settling can cause an unwanted swimming hole to develop and require you to waterproof your basement to limit water damage. 

Why Do I Have to Waterproof My Basement? 

You don’t need to experience a natural disaster to face a flooded basement. Even the most modern and robust foundations can fall victim to water penetration. Cracks in a basement floor or wall make an easy place for water to enter with little resistance. Additionally, concrete is a porous material, so if the soil surrounding your home becomes saturated, you may find water seeping right through a perfectly intact foundation. 

Whatever the cause, sealing your basement against water is crucial for maintaining a dry basement over the long term. There are several ways to waterproof your basement effectively, and the best course of action for your home may differ from your neighbors’ house because it depends on how the water gets inside. 

How Much Does It Cost to Waterproof a Basement?  

The cost of waterproofing your basement depends on how the water enters and the best method of keeping it out. Sealing the walls and floor as a DIY project and adding a dehumidifier can cost $600 to $1,000, which is minor compared to mold remediation and water damage repair.

If the problem is more severe, landscaping, installing a sump system, major repairs, or all of the above may be necessary to eliminate the issue, costing several thousands of dollars. Expect costs to vary widely between $4,000 and $10,000 or more.  

How to Prep for Waterproofing a Basement

As with most home repair and maintenance projects, the first step is to figure out where and why the problem exists. Fortunately, concrete walls and floors give up their secrets pretty easily. 

A thorough cleaning of the area will reveal mold spots, efflorescence, or discoloration, which can tell you exactly where the water is penetrating. To fully understand your basement needs, you may consider hiring a waterproofing contractor for assistance. 

How to Waterproof Your Basement

A woman using a dehumidifier in a room
Photo: maryviolet / Adobe Stock

Knowing the various procedures for waterproofing a basement will clue you into what your situation requires. Your basement may only need preventative measures to ensure that water infiltration doesn’t happen, or more intense methods could be necessary to stop a problem and keep it from happening again. 

Remove Water and Mold

To protect yourself, you must avoid working in standing water or areas of heavy mold infestation. 

  1. Wait until the standing water is gone before attempting any work. Use a wet/dry vac to remove puddles from the floor. 

  2. Mix one cup of bleach per gallon of water and a stiff-bristled brush to remove small amounts of mold from affected areas. 

  3. For large amounts of mold, hire a mold removal specialist near you to remove it from the property. 

  4. Clean the walls with a mix of mild soap and water to expose any previously unnoticed areas of water infiltration. 

Install a Dehumidifier

In mild cases, a powerful residential dehumidifier might prove effective enough to postpone or avoid other waterproofing approaches. 

  1. Place a dehumidifier in a central location. Consider running two of them if the space is large or the basement is particularly humid. 

  2. Ensure that you empty the machine’s reservoir often or that its drain line empties directly into a floor drain. 

Seal Windows and Doors

Some water problems aren’t coming from the concrete part of the foundation at all. If that’s the case, you’ll need to seal your doors and windows.

  1. Check window wells to ensure the soil level is well below the bottom of the basement windows. 

  2. Caulk around basement windows inside and out to prevent water from seeping in. 

  3. Caulk around any exterior doors and ensure that the threshold properly seals against the floor to prevent rainwater from trickling underneath.

Repair Cracks 

Cracks can occur anywhere on the floor or walls. Scope out areas near windows, doors, corners, and the bottom of walls for cracks of any size.  

  1. Use a wire brush to remove loose dirt and debris from cracks.

  2. Mix a small amount of hydraulic cement with water until it reaches a thick but workable consistency.

  3. Fill the cracks by forcing the cement into them with your fingers and a putty knife. Wear latex or similar gloves to prevent skin irritation. 

  4. Work quickly as hydraulic cement begins to cure within a few minutes.

Seal Concrete Surfaces 

A man scrubing a wall with a wire brush
Photo: yupachingping / Adobe Stock

Applying a waterproof paint substance to your basement walls stops water from seeping in and is an excellent safeguard for basements that haven’t experienced water infiltration. 

  1. Scrub the walls clean of dirt, debris, efflorescence, salt, lime, mildew, or mold. You’ll need to reach bare concrete for the waterproof paint to adhere properly. 

  2. Remove any existing paint with wire brushes or hire a paint removal specialist to sandblast the walls and floors if necessary. 

  3. Apply three coats of waterproof paint with a roller or brush to areas suspected of leaking or seeping water. 

  4. Apply two coats of the same waterproof paint to all other concrete surfaces. 

Alter Landscaping

You can often eliminate basement water problems by changing the landscaping in your yard to improve runoff. 

  1. Dig out window wells until the soil is several inches below the bottom of the windows.

  2. Keep your home’s gutters clean, ensure the downspouts remain in working condition, and that they deposit runoff well away from the foundation. 

  3. Add dirt to the exterior perimeter of the house to develop a 2-inch-per-foot slope away from the foundation. Ensure that the soil doesn’t reach the height of the home’s siding or sill plate. 

  4. Remove any vegetation within a foot of the foundation.

  5. Refrain from watering or installing an automatic watering system near the foundation. 

Install Interior Drainage System

Consider installing an interior drainage system for severe water problems. That way, you can ensure that your basement remains dry to protect a future conversion to living space. 

  1. Cut the concrete floor around its perimeter with a jackhammer and dig a trench as deep as the foundation footings.

  2. Partially fill the trench with several inches of gravel. 

  3. Create a hole and install a sump basin. 

  4. Install perforated drainage pipes onto the gravel in the trench to create a system that drains water toward the sump basin at a rate of ¼ inch per linear foot of travel. 

  5. Connect the drain pipe system to the sump basin.

  6. Cover the perforated pipes with more gravel, a sheet of plastic, and concrete to match the floor’s height. 

  7. Install a sump pump in the basin and a drainage pipe to the home’s exterior. 

Tips for Waterproofing a Basement   

Here are a few tips to remember when tackling your basement’s water issue. 

  • Remove the water, clean the space, and remediate mold as the first step of any basement waterproofing project. 

  • A thorough cleanup will likely tell you where and how the water is getting through the walls and floor. 

  • The best solution may not be the same as your neighbors’ homes. Get an inspection to ensure you’re attacking the problem with the most effective method. 

  • It may be more cost-effective to hire a professional waterproofing service than to spend money on successive guesses until you resolve the problem.  

DIY Basement Waterproofing vs. Hire a Pro

A professional waterproofing a basement floor
Photo: Niko_Dali / Adobe Stock

In many cases, the most challenging part of waterproofing the basement is devising the best plan for your home. Once you locate the leak source, you may be able to solve minor issues on your own, such as sealing windows or repairing cracks.

On the other hand, If you’re dealing with standing water or discover a large amount of mold during the process, contact a nearby mold remediation company before taking the risk of getting rid of it yourself. Of course, your best bet is to hire a local basement waterproofing company that has the expertise and the equipment necessary to ensure the best resolution.

Frequently Asked Questions

The best method for waterproofing a basement starts during the construction phase of the house by coating the foundation and basement walls with a membrane and sealants designed for the purpose. The next best solution is the one that’s most effective at resolving the problem unique to your situation, which could include sealing, landscaping, mechanical means, or all three. 

Need professional help with your project?
Get quotes from top-rated pros.