How to waterproof already painted wood

Written by claudia henning
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How to waterproof already painted wood
Proper protection helps keep painted wood from fading. (Jupiterimages/Stockbyte/Getty Images)

Painted wood surfaces, such as siding, decks or patio furniture, need a barrier from moisture. The optimal method is by adding a layer of moisture-resistant primer to the wood before applying a finishing layer of paint. The experts at Home Improvement Super Pages state that "the problem is that wood is a notoriously thirsty substance, and it is easy for water to get absorbed into the grain itself." For wood that's already painted, adding a layer of wood sealant is the easiest method for waterproofing. Larger projects can take a couple of days to complete, but the added protection is necessary to combat moisture damage.

Skill level:

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Things you need

  • Liquid detergent
  • Water
  • Bucket
  • Cleaning brush
  • Garden hose
  • Polyurethane or silicone-based wood sealant
  • Paint sprayer
  • Safety glasses

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  1. 1

    Mix 60 ml (1/4) cup of liquid detergent with 4.5 L (1 gallon) of water in a bucket. Scrub the painted wood surface with a cleaning brush dipped in the soapy water.

  2. 2

    Rinse with clear water using a garden hose. Allow the surface to dry for two to three hours.

  3. 3

    Apply an even layer of silicone-based or polyurethane wood sealant using a paint sprayer. These products are available at all home improvement centres. Give the sealant product 24 hours to completely dry.

Tips and warnings

  • For complete moisture protection, it's best to strip the paint, and add a primer coat. Clear coat sealants won't last as long without a layer of primer coat beneath.
  • Wear safety glasses when using chemicals, such as sealants.
  • Work in a well-ventilated area to minimise the fumes.

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