wikiHow to Seal a Deck

Exposed to the elements and walked over, scratched, and scraped, wood decks tend to develop mold and other problems rather quickly. Although a quick wash might make your deck look nicer, anything short of a good sealing will leave you with crumbling planks and unappealing colors. Deck sealing is best done before the rainy season and when you know there will be lots of sun for your deck to dry under. This article will teach you how to seal a deck with water-resistant sealant that can stand up to harsh weather.


  1. Image titled Seal a Deck Step 1
    Test the water resistance of your deck by spraying some water from a hose onto its surface.
    • If the water beads up on the surface of your deck, you don't need to seal. If the water seeps into the wood, you need to seal. A deck that traps water will bend, warp and ultimately weaken.
      Image titled Seal a Deck Step 1Bullet1
  2. Image titled Seal a Deck Step 2
    Choose a deck sealer appropriate for your type of wood. Most sealers will work for any wood.
  3. Image titled Seal a Deck Step 3
    Spray down the deck with water so that its entire surface is wet.
  4. Image titled Seal a Deck Step 4
    Wipe down the deck meticulously with a scrub brush, removing all leaves, mold, and other material that has collected on the surface.
    • If you do not have a very clean deck before sealing, the deck sealer will trap in all the elements you want removed, and your problem will be exacerbated. Remember to clear any plant or anything else that could be hurt by deck sealer.
  5. Image titled Seal a Deck Step 5
    Rinse the deck again to clear any debris.
  6. Image titled Seal a Deck Step 6
    Let the deck sit for at least a day until completely dry.
  7. Image titled Seal a Deck Step 7
    Apply the deck sealer with a mop or paint roller in a corner of the deck, following any instructions provided. Use even strokes, making sure not to allow sealer to collect anywhere. Move out from the corner in such a way that you can apply sealer to the whole deck without stepping in it.
  8. Image titled Seal a Deck Step 8
    Go over the deck only once, using deck sealer sparingly. The entire deck should be covered in an even coat of a single color.
  9. Image titled Seal a Deck Step 9
    Let the deck sealer dry for at least a day before walking on it.


  • A clear deck sealer will allow the color of your deck to shine through. If you'd rather change the color, try a color sealer or stain instead.
  • Using professional deck wash at Step 3 will ensure you have a perfectly clean deck before sealing; however, washing with water and wiping should be sufficient for most jobs.


  • Deck sealer includes dangerous chemicals that should not come into contact with your eyes or mouth. Always use gloves and wear glasses if your eyes become sensitive.
  • It's common to use a power washer rather than a hose to wash down a deck. However, power washers can damage sensitive or old wood and create unsightly gashes. If you have doubts about the strength of your wood, stick with a hose.
  • A water-resistant deck is not necessarily a strong deck. Before applying deck sealer, check the strength of all your planks for rot. Remove rotted wood.

Things You'll Need

  • Hose
  • Scrub brush
  • Deck sealer
  • Mop or paint roller
  • Gloves

Article Info

Categories: Walls Fences and Decks