A wooden deck can be a place of relaxation, as long as it has been designed to provide optimum safety. Large imperfections such as a damaged support beam or broken post are immediately recognizable, and they're cause for safety concern. But small holes in the deck, such as a knot hole in a deck board, require immediate attention as well, because they too can be safety hazards. Even small holes weaken the wood and make the board unsafe. Replacing the entire board will fix the problem, but there are alternative solutions that do not involve replacement.
Don your work gloves, safety glasses and dusk mask. Wear them throughout the repair process unless you need to remove the gloves to securely grasp things.
Sweep the entire deck with your broom. Focus on the damaged area to be sure all debris is removed from the hole.
Mix the body filler with the hardening agent in the body filler package. Follow the manufacturer's instructions precisely. Use your putty knife to fill the hole in the deck board with the filler.
Sand the hardened body filler after it has cured overnight. Rub your palm sander along the length of the board to avoid disturbing the wood grain.
Wipe the dust off \the repaired area with a rag. Sweep the entire deck again to prepare it for staining. Inspect the deck boards for other damage as you clean.
Apply stain to the repaired area. Move to the far corner of the deck and rub stain into all of the deck boards with your rag. Coat the entire deck, adding a second coat of stain to the repair when you come to it.
Apply a coat of polyurethane to the deck after the stain is dry. Use your paintbrush and follow the grain of the deck boards when applying the polyurethane to avoid runs. Let the deck dry for 24 hours before using it.