Waterproofing Basement Walls From Inside

Because most basements are below grade (ground), they are more prone to accumulating excess moisture and suffering water damage but there are some common easy answers to seal an interior basement wall. How do you Waterproof a Basement wall from the inside?

  • Prep the wall of old paint
  • Wash dirt & dust off the wall
  • Plug Holes & cracks with Hydraulic Cement
  • Seal Openings in doors, windows & window wells using waterproof caulk
  • Apply a coat of waterproof masonry cement to your wall
  • Install a Sump pump
  • Use a quality dehumidifier
  • Vent Dryer outside-Cover H2O pipes

Because they’re below grade and close to the water table, basements tend to be damp. That can be a major issue for anyone hoping to finish their basement because drywall, flooring, and interior paint all perform poorly in damp conditions.

Waterproofing Basement Walls From Inside


Having lived in an old stone home with a full basement the trip downstairs below ground level brought smells of dank, moldy aroma. No matter how we worked on improving the humid atmosphere of the basement and using this space which was the full dimensions of the house above, it was a challenge.

Most people I know in new or old homes who had basements or cellars (rowhouses in the city) no matter where they lived seemed to have the same problem with moisture content and the same challenges brought on by age and the house settling.

No matter how good the rain gutter system is for the house on the outside or diverting rainwater away from the home with a drain pipe laid the length of the footer there still is a wet humid air that settles in the basement or low areas of the home and moisture or worse, water finds it ways. Is it possible to stop this from happening without digging up the outside wall?

There are basic steps that a homeowner can take to improve the situation from the inside after the most basic solutions are taken care of on the outside of the house like rain guttering because no matter how well you waterproof the inside wall if there is a deluge of rainwater laying up against the home built under grade water is going to find a way in.

Here are several solutions to internal waterproofing, the first of which involves sealing cracks and small holes in the concrete walls of basements and walls built under grade with hydraulic cement.

  • First, prep the wall old paint can be removed with a wire brush, sandblaster, or other methods by cleaning out any cracks and holes.
  • Wash the walls of dirt and dust using a scrub brush and warm water with a little bit of dish soap. If you see any mold, you can add bleach to the solution 1 cup of bleach per gallon of water.
  • Plug Holes with Hydraulic cement will expand inside cracks and crevices and create a water-tight seal from the inside out. Hydraulic Cement will set and harden very quickly, in 3-5 minutes, so have a plan before you start Use a trowel to smooth the cement before it sets.
  • Seal Openings-Use a waterproof caulk to seal doors, windows, and window wells on the problem wall
  • Apply a coat of waterproof masonry cement to your basement walls. This will seal the pores of the concrete and stop moisture from seeping through. These efforts combined with proper above-ground drainage will do a lot to prevent moisture from coming through the walls. After your holes and cracks are sealed, use a waterproof coating on your basement surfaces. Apply the concrete sealer with a quality nylon bristle brush or 3/4″ nap roller and make sure to work it into the pores of the masonry. Proper coverage and a minimum of two coats are required to warranty waterproofing


10 Steps for Waterproofing an Existing Outside Wall

What are the 10 steps for a successful solution waterproofing an existing outside Basement wall or a wall built below grade that leaks constantly when it rains .…………………… Read more



Dry Basement Solutions


  • Sump pumps equipped with a battery-backup system will continue to run even if the electricity goes out during heavy flooding. The rechargeable battery will operate for 7 to 10 hours before recharging is necessary. Alternatively, water-powered sump pumps rely on water pressure, not a rechargeable battery, to keep pumping during a blackout.
  • A Water-Powered Sump Pump will run virtually forever, as long as there’s water pressure. However, this system is only suitable for homes connected to a municipal water supply, not a well pump. Another complementary internal drain system is the French drain. However, installation of this drain type will require a professional installation and may be costly.
  • Use a quality dehumidifier in your basement to reduce condensation and help prevent mildew and mold growth.
  • Cover water pipes that cause condensation
  • Dryer vent-Dryers can cause moisture-make sure it’s vented to the outside



When do you use a vapor barrier with insulation?

If you live in a humid and hot climate, you might want to install a vapor barrier along with insulation in your walls creating an air barrier, you’ll have less humidity buildup, if you live in a cold climate, using both will work together to create thermal barriers and prevent air leaks. …………………………………………… Read more



JimGalloway Author/Editor



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