Step 1: Sweep Deck and Clear Cracks

To clean and properly seal a deck, first sweep the debris — leaves, twigs, dirt — off the top. Pay particular attention to the spaces between boards. Leaves will rot in there and rest on the joists, eventually rotting the boards. Use a putty knife to clean the crevices.

Step 2: Scrub the Wood

Clean the surface of the wood. There are several products on the market, or you can use bleach, cut half and half with warm water, and a scrub brush. This is ideal for small areas and will work wonders on algae and mildew and the like. (Straight, undiluted bleach is not advisable for a deck, and it should not sit there for any length of time.)

For larger areas, rent or purchase a pressure washer. Spray the bleach/water mixture on the boards first and let it soak in for a while before pressure washing. Make sure you cover up shrubs and plants before you start spraying bleach.

Step 3: Apply Stain or Sealer

Once your deck is clean, apply a redwood stain or a waterproofing deck sealer, which will repel water and make the deck last longer. To apply the sealer, purchase a pad with a little reservoir and brush it on. Or use a foam roller. Go over the entire deck surface with the sealer