How to Replace a Rotting Deck Board

Remove the damaged board by cutting or unscrewing it, then install a new board of matching dimensions using deck screws or hidden fasteners.

  1. Spot the Damage Early. Examine the rotting board to determine if replacement is necessary - soft spots, crumbling wood, or visible decay means it needs replacing. Measure the board's dimensions and purchase a matching replacement, plus any needed fasteners. Check if surrounding boards or joists show signs of rot that also need attention.
  2. Extract the Bad Board. If the board is screwed down, back out all screws with a drill. For nailed boards, use a pry bar or deck board removal tool to lift the board, working carefully to avoid damaging adjacent boards. If the board is severely rotted, you may need to cut it into sections with a circular saw, being careful not to cut into the joists below.
  3. Clear the Foundation. Clean debris from the joist tops where the new board will sit. Check that joists are solid and not rotting - if they're soft or damaged, they'll need repair before installing the new board. Sand any rough spots on the joists to ensure the new board sits flat.
  4. Fit the New Board. Measure the gap left by the old board and cut your replacement board to fit. Leave a small gap (about 1/8 inch) on each end for expansion. If replacing a middle board, you may need to notch around posts or railings. Test fit the board before final installation.
  5. Secure It Right. Position the new board in place, ensuring it's properly aligned with adjacent boards. Secure with deck screws driven into each joist, positioning screws about 3/4 inch from the board edges. Pre-drill holes to prevent splitting, especially near board ends. For a cleaner look, consider using hidden deck fasteners if your deck system allows.
  6. Seal and Blend. Sand the new board if needed to match the height of surrounding boards. Apply deck stain or sealant to match the existing finish, covering the entire board including cut ends. This protects the wood and helps the repair blend with the rest of the deck.