How to Repair a Crack in a Composite Deck

Composite decking is nearly immune to rot, but it occasionally will require repairs to handle splits, cracks, and other imperfections. If a single piece is fairly damaged, it may be easiest to simply replace the board. However, if you don't have extra pieces, or would like to save replacement boards for serious problems, small cracks in your composite deck can be repaired.

For best results, you should find a tube of composite filler. Avoid using substitutes such as wood putty or two part epoxy. A composite filler can often be purchased in different colors, allowing you to make your patch blend in with the surrounding board. If you can't find a tinted filler, follow any repairs by painting the crack to match the rest of the board. Of course, this is not ideal because over time the paint on the repair may crack.

Step 1: Remove any damaged areas that may have caused the crack with a chisel and hammer. Occasionally, composite decking will fail due to moisture problems: remove any soft areas or any areas that you suspect may be damaged.

Step 2: Check for structural stresses that are causing cracks in the composite decking. If you see cracks in structural members, rather than a individual piece of decking, call a professional who can address the source of the problem.

Step 3: Brush away any debris from the crack using a soft bristled brush or vacuum cleaner.

Step 4: Sand the crack and any area that may come into contact with the composite crack filler using a medium to heavy grit sandpaper.

Step 4: Clean the crack using mineral spirits and a soft cloth. Allow the area to dry before proceeding.

Step 5: Press composite filler into the crack with a plastic putty knife. Let the composite filler dry for the length of time recommended by the manufacturer, then check for shrinkage. If the crack shows a slight depression at the repair area, fill it with a second layer of filler after sanding the surface lightly.