How to Damp Proof Walls With Exterior Wall Coating

a basement with a table and chairs and a treadmill
  • 10-30 hours
  • Intermediate
  • 500-5,000
What You'll Need
Waterproof coating product
Pressure washer
Concrete cleaner (for treating mildew)
Paint sprayer, roller or brush
Broom or squeegee
Vacuum cleaner
Power drill with 12 mm drill bit
Application gun
DPC fluid
Tape measure

Damp proofing walls can protect your home from damage caused by moisture. Exterior walls made from concrete are porous and invite moisture when they are left untreated. Here are the steps for how to apply wall coating on your exterior wall.

Step 1 - Clean the Property’s External Wall

Use a pressure washer to remove dirt, moss, mold, algae, flaky paint, industrial grime, and pollutants that may have accumulated on the house’s external walls. For stubborn mold and mildew, apply concrete cleaner to the walls and rinse it off afterwards using a pressure washer. Follow the manufacturer’s instructions on how to apply the concrete cleaner, the dilution ratio, and the waiting time before you can rinse the chemical form the wall.

Step 2 - Check the Walls for Defects and Damage

Starting at one corner of the house, check the exterior walls for damage and defects. Look for loose or missing pieces and mortar joints, crumbling bricks, and cracks in the walls. Continue the inspection until you have circled the whole house. As you do so, make notes about the location of these wall defects, the nature of the defects, and the repairs that will be needed.

Step 3 - Repair Wall Damage

Keep materials and tools needed for repair at an arm’s length. Replace missing bricks, re-apply mortar, and apply putty on cracks. To lessen repair time, fix the same types of damages in one go before moving on to a different type.

For defective damp proof course (DPC), revamp this protective layer before applying a wall coating; otherwise, the wall coating will be useless if your wall experiences rising dampness from the ground.

Drill holes using a power drill with 12-mm bits six inches from the ground. Remove excess debris or dust with a vacuum cleaner. Then inject these holes with your chosen DPC fluid using an application gun. Allow the DPC fluid to dry, then you can apply mortar to seal the holes.

Step 4 - Apply Waterproof Coating Product

To apply wall coating on a vertical surface, use a sprayer, a brush, or a roller. Start from the upper section with an adequate amount of your choice of waterproof wall coating product.

To apply wall coating on a horizontal surface, use a sprayer or roller. Apply the waterproof wall coating generously. If puddles form, eliminate them by evenly distributing the wall coating across the surface using a squeegee or broom.

For both horizontal and vertical surfaces, apply a second coat before the first coat dries. After this second coat, check whether you need more coats. Very porous wall surfaces may require more than two coats.

Step 5 - Clean-Up and Disposal

Dispose of chemical products according to applicable local or state rules. For excess products that you plan to use in the future, store them according to the instructions on the labels.

Wash the tools and store them in their proper place. Use cleaning agents suitable for the chemicals. Wash up after a day's work to prevent contamination from wall coating or DPC fluid.