How to waterproof paint

Quality waterproofing additives are about the same price as latex paint, so water-repelling modifiers do not significantly increase the cost of a paint job. These additives also increase surface durability, prevent colour fading, and reduce mould and mildew problems. They make painting easier by minimising brush marks and roller drag and enhance the flow of paint over the surface as well. The slick, electrostatic-free finish of paint that contains waterproofing additives allows dirt and grime to be washed or wiped away easily--a valuable bonus.

Measure and pour four parts of latex paint into a plastic bucket.

Insert and tighten a mixing paddle attachment into the chuck of a two-speed electric drill. Set the drill to the lowest speed. Immerse the paddle in the paint and turn the drill on.

Add one part waterproofing agent to the latex paint in the bucket. Pour the additive in slowly. Continue mixing until the additive is thoroughly combined with the paint. Remove the paddle.


Paint treated with a waterproofing agent is best applied when substrate and air temperatures exceed 10 degrees C. Cold or humid weather will increase drying time. Remove all flaked or lose paint with a wire brush prior to painting. A clean, dry surface is necessary to ensure proper bonding. When using paint or stain treated with a waterproofing agent, an undercoat is not required. Certain waterproofing paint additives are suitable for mixing with either water- or oil-based latex paints and stains. Check the manufacturer's instructions before beginning your project. Once thoroughly mixed, the waterproofing agent will not affect the colour or coverage properties of latex paint or stain.

Things You'll Need

  • Latex paint
  • Liquid measuring cup
  • Plastic bucket
  • Two-speed electric drill
  • Mixing paddle drill attachment
  • Waterproofing additive
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About the Author

After graduating from the University of the Witwatersrand and qualifying as an aircraft engineer, Ian Kelly joined a Kitchen remodeling company and qualified as a Certified Kitchen Designer (CKD). Kelly then established an organization specializing in home improvement, including repair and maintenance of household appliances, garden equipment and lawn mowers.