Close up of a slightly flooded kitchen floor.

How To Waterproof A Basement

Michelle Giorlando5-minute read
UPDATED: May 08, 2023

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Water damage can be troublesome in a variety of situations, but when it comes to your home basement it can be particularly devastating. A leaky or flooded basement can cause many problems and lead to deterioration and damage to your home’s structure. If you’ve noticed moisture, mold, warped floors or walls, or any musty smells, it’s a good idea to consider waterproofing your basement.

Let’s look at how to waterproof a basement inside and outside, and the costs involved.

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How To Waterproof Your Basement: 4 Essential Steps

Finding the origin or root cause of a wet basement is essential in stopping it and helping ensure it doesn’t start again.

Some common ways water might be entering your basement include cracks in the foundation (including tiny pinhole cracks), leaky window seals or doors, or poor exterior drainage. If your yard slopes, it may cause water to pool around your foundation, leading to increased pressure, and an easy way for water to enter your home. Water might also leak through the floor if the water table your home is built on is saturated.

Once you’ve identified where the leak is coming from, you can take steps to mitigate or eliminate future water damage.

1. Clean The Basement Walls And Floor

Your first step is to clean the walls and floors by washing the dirt and dust off with soap and water. Basement waterproofing products will work best when applied to a clean surface. If you have a finished basement with furniture or carpet, you should remove them. If any upholstered furniture or carpet is damp, consider getting rid of them to avoid mold and all the issues mold introduces.

2. Seal All Cracks And Openings

Step two is the most crucial. It’s time to identify all holes, cracks and openings to be filled and sealed to stop water from entering your basement. Being thorough in at this stage will greatly reduce the chance of water damage in the future. You should carefully inspect both the basement walls and the outside foundation for small cracks. When you find them, use sealant to fill them in.

3. Apply The Waterproof Sealer 

Once you’ve sealed the smaller holes and cracks, it’s time to apply the overall waterproof sealer. This can come in the form of a masonry waterproof product (which is applied like paint) or waterproof paint. This sealer acts as a moisture barrier, which is excellent news for concrete, which is porous. Apply two coats to be extra sure it works.

4. Monitor Your Basement

Once your sealant is dry, your initial work is done. However, you should continue to monitor your basement for any water that might be sneaking in. Check both the interior and exterior of your home.

A water leak detector can help give you peace of mind by alerting you to water leaks immediately. These are generally placed where water would pool, so if you’ve got a problem spot, consider this system! They can even monitor your sump pump.

Exterior Basement Waterproofing

Basement waterproofing isn’t just an indoor issue. There are several things you can do outside to ensure moisture doesn’t creep in as well.


Gutters are important to pay attention to, as they can often lead water to run closely to your home’s foundation. This can cause issues if proper downspouts aren’t installed, or if your gutters aren’t properly cleaned out. Diverting water from your home can help ensure the water doesn’t take up residence in your basement.


If you’ve got landscaping close to the house that requires watering, you should make sure that water isn’t leaking through to the basement. The same goes for any paved walkways where water can drain in a certain direction. If you notice water pooling near the foundation, consider having your land graded away from the foundation to avoid this.

Basement Waterproofing Tips

Once you’ve waterproofed your basement and taken steps on your home’s exterior to keep water away, there are a few other factors to consider.

Install A Dehumidifier

If your basement is damp or humid even after waterproofing, think about installing a dehumidifier. This will consistently pull the moisture out of the air and save your upholstery and carpets.

You can buy a small, inexpensive one that you plug in, or you can have a professional install a stronger, more powerful unit to dehumidify your room.

Assess All Basement Appliances And Utilities 

Even after waterproofing and possibly utilizing a dehumidifier, it’s very important to check all basement appliances and utilities to ensure they aren’t contributing to the water or moisture in the basement. Inspect your washer and dryer hoses, any pipes, and even the dehumidifier itself! Do this every so often – keeping up with home maintenance and inspection is important to avoid basement flooding.

Install A Drainage System (If Necessary)

If your basement doesn’t have one, think about installing a drainage system in the floor. Generally, this will include a collection drain based at the lowest point of the basement. Any water is collected and then diverted outside by a sump pump, which turns on when a certain level is reached. Having a sump pump can even save you money on your homeowners insurance.

Cleaning the floor area around your drainage system and keeping it clear of debris and clutter should be a regular part of your basement utility inspection routine.

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How Much Does It Cost To Waterproof A Basement?

As with most things, the cost to waterproof a basement is based on a variety of factors:

  • How big is your basement?
  • How damaged are the floors and walls?
  • How is water getting in?
  • Are your pipes leaking?
  • Does the ground outside need to be graded away from the home?
  • Does a drainage system need to be installed inside or outside?

The costs to waterproof your basement can range anywhere from $4,000 – $11,000. Expect to pay about $3 – $10 per square foot. The amount of water that is causing issues in the basement and how much labor is needed for the repair are both factors that affect the overall cost.

Compare quotes from basement or foundation waterproofing companies to get a better idea of what you can expect to pay for basement waterproofing in your area.

The Bottom Line

The cost and overhead of waterproofing a basement can vary widely depending on your house’s current needs and setup. The most effective way to waterproof is typically to hire a professional to do an exterior waterproofing job rather than pursuing a DIY project. This renovation is typically fairly pricey, so if you want to protect your home from water damage in this way, you might want to look into financing options. A cash-out refinance is a good path forward for many homeowners, as it lets them turn their current equity into a means to protect their investment in their home through precautionary renovations. If this sounds appealing, why not start the process to get a cash-out-refinance today?

Need extra cash for home improvement?

Use your home equity for a cash-out refinance.

NMLS #3030

Michelle Giorlando

Michelle Giorlando is a freelance writer who lives in metro Detroit. When she's not writing about homeownership, finances, and mortgages, she enjoys performing improv, gardening, and befriending the wildlife in her yard.