How to Replace a Rotted Deck Board

One soft spot doesn't mean the whole deck is shot. Swapping a single board is a Saturday job if you have the right tools.

Probe the questionable boards with a screwdriver. Anything that sinks more than 1/4" without firm resistance is rotted. Mark the boards to replace, and check neighboring boards for rot creep before you stop.

Cut the bad board over a joist on both ends with a circular saw set to the board's thickness (usually 5/4" or 1"). Pry up the rotted section and remove old screws. Check the joist itself — if the top of the joist is rotted, sister a new piece of pressure-treated 2x6 alongside it before laying the new deck board.

Cut a replacement board to fit, ideally from the same lot as the original. New cedar or composite won't match weathered boards — but it'll grey out within a year or two. Match the gap spacing of surrounding boards using a 16d nail as a spacer.

Drive two deck screws per joist crossing, predrilling near the ends to prevent splitting. Wipe the new board down with deck cleaner, and consider sealing or staining the whole deck the same season — partial sealing always looks blotchy.