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How to Repair a Cedar Deck and Fill Cracks

A natural, cedar wood deck can be a beautiful, value-added addition to any home. Cedar is shrink and warp resistant, with a natural resistance to insects and fungus. Over time, however, damage to a deck can occur. Problems such as dry rot, mildew, popped nails and cracked boards must be caught and repaired early, before they worsen and necessitate a complete deck rebuilding. All of these issues can be dealt with by most homeowners, and once you've made needed repairs, regular maintenance can keep your cedar deck looking as if it were just installed.

Cedar deck in good repair.
  1. Clean the deck thoroughly to better reveal problem areas. Spray the wood with clean water using a garden hose. Prepare a cleaning solution consisting of 4 oz. of TSP (tri-sodium phosphate), 1 qt. of bleach and 3 qt. water. Mix the cleaner in a hand pump sprayer and apply the cleaner to the deck surface. Allow the cleaner to sit for 20 minutes. Scrub the surface of the deck with a hard bristle brush, removing any dirt and debris. Apply water to the cleaning solution if it begins to dry out during cleaning. Use a power washer, set no higher than 500 psi, to remove the dirty cleanser from the deck and to completely rinse the cedar. Allow the surface to dry for three days before continuing with repairs.

  2. Remove any mildew on the deck using a deck cleaner formulated for use on cedar wood decks. Follow the manufacturer's instructions on how to apply the cleaner to remove mildew. Rinse the cleaner residue from the boards when finished and allow the boards to dry completely.

  3. Pound back any nails that have popped up. Hold a drift punch against the nail and tap the end with the hammer to knock the end of the nail slightly below the surface of the deck. Use slightly larger and longer nails for those in need of replacement.

  4. Repair small cracks in the cedar wood by spreading a thin layer of epoxy over the cracks. The epoxy will seal the crack, keeping it from widening into a more serious split in the wood and add strength to the cracked area. Using a paintbrush, spread the epoxy the length of the crack and along the insides. Allow the epoxy to dry overnight. More serious cracks, those more than 1/4-inch wide, will require board replacement.

  5. Remove and replace warped, insect damaged, broken or dry-rotted boards. Remove the boards by first removing the nails that secure the board. Lift the board from its placement by prying the board up where it's been nailed. Use the end of a claw hammer or a small pry bar to lift the board from its placement. Measure the vacant space. Cut a spare piece of cedar the same width as the old board and secure it in place using deck nails.

  6. Seal the entire surface of the cedar deck with wood sealant to protect it from damage from the elements. Allow the sealant to dry overnight before using.