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How to Waterproof Basement Walls

DIY Steps to Waterproof Your Basement Walls from The Inside

Learning How to Waterproof Basement Walls is one of the easiest DIY projects a homeowner can accomplish.  If you’re dealing with a wet or musty basement and trying to figure out how to solve the issue yourself, follow these five simple steps to waterproof the inside basement walls 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 unwelcome moisture, but do they work? 

In many cases, waterproofing the inside of basement walls is the First, Best, and by far the Least Expensive option when waterproofing a basement.

If you have water seeping through the block or concrete walls in your basement, Follow Our step-by-step waterproofing Guide, and once you’re completed – you should have a fully dry basement again.

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

 

How To Waterproof Your Basement in 5 Steps

 

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

Your first order of business – Is to determine the Source of the moisture leak.

Look for Cracks in Basement Walls:

basement wall crack
Locating basement wall cracks – besthomegear.com

Visually Inspect all the exposed concrete basement walls inside of the home – from floor to ceiling. 

Look for any hairline cracks that allow outside moisture to penetrate, and mark the location with dry chalk or painter’s tape.  This will allow you to quickly locate and patch each wall crack before patching the walls.

Look for Wet Spots on Basement Walls:  

leaks in basement walls
Find a basement water leak – besthomegear.com

Tips & Tricks to Discover Sources of Water Leaks:

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

Examine Leak Test 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, waterproofing products can fix such a problem by using a portable room dehumidifier or 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, pressing against the outside of your basement walls.  In this case, the most logical problem is providing suitable drainage outside to avoid high rainfall or unusual flooding 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)

Use a stiff brush to remove 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, a powdery substance left from salt pushed through the masonry wall from the outside ground.

removing white powder from basement walls
removing efflorescence from masonry walls – besthomegear.com

This powdery substance prevents waterproof paint and sealer won’t adhere to concrete or masonry.  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 – besthomegear.com

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 up to 1/4″ wide – (See Step 1) by 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 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 expandable acrylic formulas similar to regular paint. You apply them in a much thicker layer by rolling, brushing, or spraying.

Of all the good “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 product! – One gallon only covers 100 square feet.  A close second material, but slightly more expensive, is the Drylok Waterproof paint for the interior or exterior, which is White.

  • Silicate-Based Concrete Sealer:

Also known as a densifier, 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 specific 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 to Walls

Once all wall cracks have been filled or patched, you can begin waterproofing your basement’s interior block or concrete walls. This one of the most accessible 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 three application methods for Waterproofing Basement Walls: 
  • 18″ (or standard 12″_ Paint Roller/Pan (To paint roll the walls)
  • Four ft. paint pole (attaches to paint roller)
  • 3″ Wide Paint Brush (to trim the perimeter)
  • Painters tape (if masking off the 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. 

After putting on some disposable paint gloves, 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 completing these steps for each wall of your basement.

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 regular latex paint.


Waterproofing Walls from the “Outside” of Home

If, after sealing basement walls inside your home, you still find moisture intrusion, you need to consider removing the water penetration outside the walls.  This is the surest way to eliminate water intrusion in more extreme circumstances.

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

This option involves installing a waterproof coating on the outside of basement walls and installing drainage tile and a sump pump to evacuate the high water table.

Moreover, it requires professional help and equipment since it involves digging all around the house to reach the full depth of the foundation wall. 

Conclusion

There you have it, our detailed guide on waterproofing 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 the Basement “Floors” with the Basement “Wall” sealer?

Yes, you can and should fill any cracks in your floors and use a basement wall sealer for basement floors.  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?

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

Can I Waterproof the Basement Walls Myself?

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

Video:  How To Waterproof Basement Walls with “Drylock”


 

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Additional Reading & Resources for Homeowners

Kevin
Kevin
Kevin is the author and editor for Best Home Gear. In addition to his work in publishing, Kevin enjoys exploring the Outdoors in Michigan and Arizona, Hiking, Cycling, Fishing, Reading, and Completing Projects for the Home and Garden.

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