How to Seal Wood Fences

Locate a pressure washer that has a pressure per square inch (PSI) rating of 500 or less, which will not damage the wood. Fill it with cold or lukewarm water according to the instructions provided by the manufacturer. Put on safety glasses, and hold the sprayer at least 1 to 2 feet away from the wood fence as you spray it to remove all dirt and stains.

Allow the wooden fence to dry completely for 24 hours until it is no longer damp to the touch or dark in color.

Open a can of wood sealer, also called wood waterproofer, and pour it into a clean garden sprayer. Professional paint spraying systems are also acceptable application methods.

Close up the garden sprayer and place drop cloths on the ground under the fence and over any nearby plants or shrubs to prevent them from getting sprayed.

Spray the sealant onto the wooden fence slats, using an up-and-down motion to cover each board before moving on to the next one. Continue spraying each board until they are all covered with a thin layer of the sealant.

Set the garden sprayer aside and insert a wide paintbrush into the remaining sealant within the bucket or in the sprayer.

Brush the entire wooden fence with long, even strokes to work the sealant into the wood grain. You don't need to redip the brush often, since you are not really applying additional sealant. Make sure to brush the top and sides of each board, which may be missed when sprayed.