How to Apply Crystalline Waterproofing Material to Basement Walls

  • 8-16 hours
  • Intermediate
  • 400-650
What You'll Need
Wire brush
Cold chisel
Masonry brush
CWM material
Shop vac

Crystalline waterproofing material, or CWM, is a great way to protect your basement walls from water and freezing. CMV is applied to basement walls; it penetrates the porous cavities of the cement; which changes the porous concrete into a waterproof solid. It is a great product to use in a wet basement where water seepage is a problem. Installation is straightforward and can be done by any do-it-yourself homeowner.

Clean Concrete Wall Surface

Crystalline waterproofing material will only adhere to the concrete surface if it is free from any other obstructions. Use a wire brush to remove loose concrete and paint. A hammer and a cold chisel may be needed for large pieces of concrete that must be removed. If there are multiple layers of paint that cover a wide area, try power washing or sandblasting the surface.

Repair Concrete Surface

If water has been leaking through the surface of the concrete, you will need to do some repair work before applying the waterproofing material. Use a shop vac to suck up any of the dirt and loose concrete in the cracks or crumbling areas.

Mix some concrete patch material or use some liquid concrete in a tube. Spread it over the surface with a trowel and make sure that the entire crack or hole is full of the patch. Let it dry and set before doing anything else to the surface.

Wet Surface of Concrete with Water

Before you apply the waterproofing material, wet the concrete thoroughly. You do not want to soak the area, but it should be wet before you apply any of the waterproofing material.

Mix Waterproofing Material

Mix the crystalline waterproofing material with water in a bucket. Apply just enough water that the material becomes a thick paste. Do not be alarmed when the material starts to heat up. The chemical process of the water and the material creates this type of chain reaction.

Apply Waterproofing Material to Concrete Wall

Once the material is mixed to a thick paste, apply a thick coating to the concrete wall. Use a masonry brush to spread the waterproofing material over the surface of the wall. It should be thick and even.

Keep Wall Wet While Applying Material

Once the crystalline waterproofing material is applied to the surface of the concrete, you must keep it wet for at least 48 hours so that the materials will penetrate the porous concrete. If it sets too quickly, it will not have a chance to impregnate the concrete wall.

Sprinkle Over New Concrete Pours

Another way to apply this type of waterproofing material is to sprinkle it over new concrete pours. If you are building a new foundation, sprinkle the material over the surface of the wet concrete. As the concrete dries, it will cause the material to solidify inside the wall, creating a waterproof seal.