Don’t Waterproof Basement Walls on the Inside

Do not waterproof the basement wall on the inside. The problem is that the cement block is hollow. If you prevent water from leaking out of the cinder block, it will only fill the block with water. You must stop the water getting to the house or waterproof the basement wall or sooner or later it will leak or cause damp spots that will support mold growth.

When it comes to basement walls I recommend stopping dampness and leaks by directing the water away from the house. Keep the water away from the basement and your dampness will go away.

If you trap water in the wall or let water flow through the wall, the block and mortar will become weaker. To prevent water from dissolving the block or mortar joints I recommend draining the water out of a hollow wall.

To check or drain a wall, drill 1/4-inch (or so) holes at the base of the wall about every four feet. You should be able to feel the hollow web in the block. After a couple of holes you will know where the web holes are. This will drain any stored water out onto the floor.

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These drain holes also provide an early warning system if water gets into the wall again. Next rain storm you will be able to accurately identify where water is entering your wall.

Check for improper landscaping that is allowing water to flow towards the house. If you allow water to accumulate along the side of your building, sooner or later it will find a way into the basement.
This situation can be corrected by raising the grade of the soil around the house. Be sure water drains at least six feet away from the house and within two months your basement will dry up.

I do not promote basement-waterproofing systems that collect water inside the basement.

Installing interior gutters at the base of the wall or cutting the basement floor and installing inside drain tiles promote water flow through the block wall or under the footings.
Prevent water from getting accumulating around the basement and keep your block wall and footings dry.

Cure the problem; don’t treat the symptom.