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How to Waterproof Basement Walls

Learning How to waterproof basement walls is one of the simplest DIY projects a homeowner can accomplish themselves.  If you’re dealing with a wet or musty basement and trying to figure out how you can solve the issue yourself, just follow these 5 simple steps to waterproof basement walls from inside the basement of your home. 

You’ve probably come across many articles on how to waterproof a basement or advertisements for basement wall sealers, that claim they will rid you of the unwelcomed moisture, but do they really work? 

In many cases, waterproofing the inside of basement walls is the “First and Best”, and by far the least expensive option to start with – when waterproofing a basement.

Here’s our step-by-step guide, that once you’re completed – you should have a dry basement.

waterproof basement walls - Best Home Gear
How To Waterproof Basement Walls – Besthomegear.com


How To Waterproof Your Basement:  5 DIY Steps



Step 1:  Determine “Where the Basement Water is Coming from”

Your first order of business – Determine the source of the unwanted moisture.

  • A).   Look for Wall Cracks:

basement wall crack
locating basement wall cracks 

Visually Inspect all the exposed concrete basement walls inside of the home – from floor to ceiling.  Look for any hairline cracks that are clearly allowing outside moisture to penetrate inside, and mark the location with chalk and or painter’s tape.  This will allow you to easily locate and patch each wall crack, before patching the walls.


  • B).   Look for  Wet Spots:  Tips & Tricks to Discover Source of Water

leaks in basement walls
find a basement water leak

For wet or wet-stained walls without cracks, You can easily determine the cause by taping a piece of aluminum foil (about 1 sq. ft) on the inner side of your basement walls and leaving it there for 24 hours. Results:

  • 1)  If you find water condensation on the Outside surface of the foil, then you’re dealing with high humidity inside your basement. Alternatively, by using waterproofing products, you can fix such a problem using a portable room dehumidifier or by installing a whole-house dehumidifier system.
  • 2)  If you find condensation on the Inside surface of the foil, water is seeping through the basement walls from the outside.  The wetness is likely coming from improper drainage around the outside of your foundation walls. 
  • In this instance, the soil around your house has a high water table, is pressing against the outside of your basement walls and.  In this case, the most logical problem is to provide suitable drainage outside, to avoid high amounts of rainfall or unusual flooding, which may occur in your area.
  • This issue may eventually need to be addressed, which we address at the end of this article: “How to waterproof walls from the Outside”.


Step 2:  Prep Walls Before Applying Waterproofing Material

Use a stiff brush to remove any loose impediments, dirt, or cobwebs from the walls. In addition, You may notice some white stains on the surface of concrete or masonry walls.  This is called efflorescence and is a powdery substance left from salt pushed through the masonry wall from the ground outside.

removing white powder from basement walls
removing efflorescence from masonry walls

Waterproof paint and sealer won’t adhere to concrete or masonry, with this powdery substance in place.  To neutralize efflorescence before you waterproof walls, use Drylok liquid or Drylok powder etch first.


Step 3:   Fix Wall Cracks From The Inside


drylok - best home gear
apply drylok crack sealer

Now that you’ve determined how the water is getting inside, it’s time to fix your leaky basement walls.

  • Fill Cracks in Walls:

    First, repair all basement wall cracks (hairline cracks, and up to 1/4″ wide) – from Step 1;  using a top brand of epoxy wall crack sealer. We recommend PC Products crack sealer because it is a highly rated, affordable, and permanent concrete crack sealer.  PC Products includes one tube of two-part epoxy and is delivered efficiently to cracks with your own standard caulk gun.  

  • Note:  If you have wide basement wall cracks – exceeding 1/4″ – you should install concrete wall crack plug material such as Drylok Fast Plug.  This product can even stop water under pressure from the outside.


Step 4:   Buy the Right Waterproof Basement Wall Sealer

Depending on the condition of your basement walls, the severity of cracks, or whether your basement walls have been previously painted, you will need to determine the best concrete wall sealer for your particular situation. 

  • Waterproof Paint:

Waterproofing paints: these are acrylic formulas that are similar to regular paint. The difference is that you apply them in a much thicker layer, whether by rolling, brushing, or spraying.

Of all the good waterproof “paint” products on the market, our first choice is KILZ Interior/Exterior waterproof paint – white from Amazon.  It is easy to apply and water-based for simple clean-up.  Get Enough – One gallon only covers 100 square feet.  A close second, but slightly more expensive, is the Drylok Waterproof paint for interior or exterior, which is White in color.

  • Silicate-Based Concrete Sealer:

Also known as densifiers, silicate is a mineral sealer that will dry with a “Clear” transparent finish and is therefore only suitable for virgin concrete walls (walls that haven’t been painted or sealed before).  One of the best silicate-based wall sealers on the market is the Siloxa-Tek 8500 product from Amazon.  This is a ready-to-use pre-mixed gallon, with 250 square feet (10 ft. x 25 ft.) of wall coverage.

Silit sealers work by chemically reacting with certain components of concrete or brick – then forming a solid waterproof surface. Apply silicate-based sealers with a roller, brush, or sprayer. It’s relatively simple, and won’t peel or flake off.

  • Concrete coatings:

If you have done extensive wall crack repair, you may wish to conceal all the patches with a concrete coating.  Concrete coatings are cement-like coatings that stick permanently to concrete and masonry walls once they dry.

Use a heavy brush (preferably with Tampico bristles) to apply this product. Swirl the brush at the end to smooth out the final look. We recommend looking at Floor Tex 40 from Seal Krete.


Step 5:   Apply Waterproofing Material

Once all wall cracks have been filled or patched, you can begin waterproofing the interior basement walls. This actually one of the easiest parts.

waterproofing basement walls - best home gear
Waterproofing basement walls – besthomegear.com


Note:  If you have applied any crack sealer or crack patch material, allow at least 4 hours of curing time before applying a waterproof sealer or waterproof paint to the walls. 

These are the 3 application methods for Waterproofing Basement Walls: 
  • 18″ (or standard 12″_ Paint Roller/Pan (To paint roll the walls)
  • 4 ft. paint pole (attaches to paint roller)
  • 3″ Wide Paint Brush (to trim the perimeter)
  • Painters tape (if masking off perimeter)
  • Spray gun/compressor (optional)

In most cases, we recommend using a combination of a 3″ paintbrush, and a wide paint roller with a paint pole attachment – when applying the basement wall sealer. 

Simply, start the painting process with a 3″ wide paintbrush, by cutting in the paint at the floor lines and top of the basement walls.  Follow that step by using the paint roller (fill in the box), overlapping rows, and complete these steps for each wall.

Optional Paint Spray Method:  If you have paint spray equipment and expertise, you may additionally choose to use a professional paint spray gun and compressor.  However, the very best basement wall seal products, especially paints are thicker than normal latex paint.


Alternate Method:  Waterproofing Walls from the “Outside”

If after sealing basement walls from the inside you still are finding moisture intrusion, you will need to consider removing the water from the outside of the walls.  This is the surest way to eliminate water intrusion in extreme circumstances.

However, it is definitely not the cheapest way to waterproof and can cost up to several thousand dollars depending on the size of your project.

Moreover, it requires professional personnel and equipment to achieve, since it involves digging all around the house to reach the full depth of the foundation walls; installing a waterproof coating on the outside of basement walls, as well as installing drainage tile and a sump pump to evacuate the high water table.


There you have it, our detailed guide on how to waterproof basement walls. Remember, none of these solutions will work efficiently unless the cracks and gaps in the walls are properly sealed. So make sure you use generous amounts of product to fill the cracks and gaps before you seal basement walls.


FAQ (Frequently Asked Questions:  “How to Seal Basement Walls”


Can you Seal Basement “Floors” with Basement “Wall” sealer?

Yes, in fact, you can and should fill any cracks in your floors, and use a basement wall sealer for basement floors.  Do consider, however, that if you use “white” basement waterproof paint, get it tinted first (gray or brown) to hide foot traffic or dirt.

Does Waterproof Paint stop the water from coming in?

On its own, waterproof paint or waterproof sealer for concrete will help prevent moisture on solid concrete and masonry walls on its own, However, if you have cracks in walls you must first plug, or fill the wall cracks before applying basement waterproofing paint or sealer.

Can I Waterproof Basement Walls Myself?

Yes, if you have even minimal do-it-yourself skills, you can use our how-to waterproof basement guide above, and waterproof walls from the inside of your home. Doing the job yourself is also the cheapest way to build or accomplish any homeowner repair.

Video:   How To Waterproof Basement Walls from Drylock


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About the Author: As a Builder, Realtor, and Property Manager for 25+ years, Kevin has used Tools and Outdoor Equipment for the bulk of his career. Managing property in Michigan and Arizona, he also tests many of the products he reviews firsthand, in vastly different climates and conditions. Our goal at BestHomeGear.Com is to share first-hand experience - Providing "Unbiased" Product Reviews, DIY Guides, and useful Home & Garden Techniques for our faithful readers - Homeowners just like you!

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