How to Repair or Replace a Deck Board
Rotted or cracked deck boards are a safety hazard and should be replaced before they fail under load. Replacing individual deck boards is a straightforward DIY job that dramatically improves the safety and appearance of your deck.
Likely Causes
- 1Wood rot from prolonged moisture exposure and lack of sealing
- 2Insect damage (termites or carpenter ants)
- 3Physical damage from heavy loads or impacts
- 4UV degradation causing splitting and checking
- 5Improper installation — boards installed too close together, trapping moisture
Rotted deck boards are a structural safety hazard. A person can fall through a rotten board. Replace promptly.
How to Fix It: Step by Step
- 1Identify all damaged boards
Walk the deck slowly and probe suspicious boards with a screwdriver. Sound wood resists the screwdriver. Rotten wood is soft and the screwdriver sinks in easily. Mark all boards to replace.
- 2Check the deck structure
While you have boards removed, inspect the joists and beams underneath. If the joists are soft, you have a bigger structural problem that needs professional attention.
- 3Remove the damaged board
Use a reciprocating saw to cut through nails holding the board to the joists. Pry up the cut pieces with a flat bar. Be careful not to damage adjacent boards.
- 4Purchase replacement lumber
Match the width and thickness of existing boards. Pressure-treated lumber is standard for decks. Cedar, redwood, or composite are premium alternatives. Composite won't rot.
- 5Install the new board
Lay the new board in place. Leave a 1/8" gap on each side for drainage and expansion. Fasten with 3" decking screws (two per joist). Pre-drill near board ends to prevent splitting.
- 6Seal and finish
Apply deck stain or sealant to the new board (and ideally the whole deck) to protect against moisture. New pressure-treated lumber should dry for 30–90 days before staining.
Materials & Tools Needed
Warning Signs It's Getting Worse
- ⚠Boards feel springy or bouncy when walked on
- ⚠Visible gaps or unevenness in the deck surface growing over time
- ⚠Rust stains bleeding from fasteners (fastener corrosion weakening connections)
- ⚠Deck wobbles or sways when you walk near the edge
When to Call a Professional
Call a contractor if more than 20% of boards need replacement, if the joists or beams are rotted, or if the deck ledger (where it attaches to the house) shows rot or damage.
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