Replacing a deck board that is rotten, split, or damaged in some other way is both a safety measure and an improvement to the way the deck looks. If the board is not broken but just looks bad because of something like a stain, you might just need to take it off, flip it over, and fasten it back on. If there is damage, you can take out the whole board and put in a new one, but this isn’t always possible or sensible. You can also replace just the damaged part of the board if you need to. This is as easy as cutting out the damaged part of the old board and putting in new material in its place. Getting the joists and the new board ready is the most important part of this easy project.
What You’ll Need
Equipment / Tools
- Eye protection
- Speed square
- Carpenter’s pencil
- Screwdriver (optional)
- Pry bar
- Circular saw
- Miter saw (optional)
- Drill with driver bit and 1/8-inch twist bit
- Tape measure
- Brush for wood sealer application
- Paintbrush for wood finish
- Deck wood sealer (clear)
- 16d galvanized nails
- 2 1/2-inch galvanized deck screws
- 1 24-inch pressure-treated 2×4 lumber
- 3 1/2-inch galvanized deck screws
- Deck board lumber to match existing decking boards
- Deck wood finish (as needed)
- 3-inch galvanized deck screws
- Plan the Cut
The goal is to cut out the damaged part cleanly and make the repair look as natural as possible. Look at the part of the deck board that is broken and decide where to make the cuts. The replacement board should be the right size so that the end joints don’t line up with the joints in the rows next to it. To make the deck look more natural, it’s best to put the joints in the boards in different places from row to row. Even if the damaged area isn’t very big, it’s best for the new section to span at least two joist spaces. This way, it’s supported at least three places: at each end and at least one joist in the middle. Find the two damaged joists on either side of the damage. Using a speed square to mark square and straight cutting lines, draw cutting lines across the board that are flush with the inside edges of the joists.
- Remove the Damaged Board
Put on safety glasses before you cut. Cut along the lines with a jigsaw and a coarse wood-cutting blade. Cut the damaged board off right where it meets the joists. If you know how to use this method, you can use the speed square to guide the saw. If you want a straight cut, just carefully follow the line. Use a drill driver, a screwdriver, or a pry bar to take out the screws and nails holding the damaged part of the decking board in place. Take out the board part.
- Seal Any Joist Rot
Check the joists below the damaged board you just took out for rot and remove it if you find any. Use two coats of clear sealer to treat and protect the joists where the rot was removed.
- Add the Joist Reinforcement
Add a reinforcing joist made of clear-sealed, pressure-treated wood. Place the new joist right next to the broken one. Use 16d nails or 3 1/2-inch deck screws every two feet to attach the new joist.
- Install the Support Cleats
Cleats give the new piece of decking a place to rest. Use a circular saw, miter saw, or jigsaw to cut two pieces of 2×4 lumber that are 12 inches long for the support cleats. Drill two pilot holes about 2 inches from the ends of each cleat with a drill and a 1/8-inch twist bit. Place a support cleat on the inside face of one of the exposed joists, right in the middle of where the board was taken out. The cleat’s top should be level with the top of the joist. Put four 2 1/2-inch deck screws through the pilot holes and into the joist to hold the cleat in place. Do the same thing with the other cleat and joist.
- Cut a New Decking Board
Cut the new decking board so that it fits snugly in the hole. If the new board is already rounded, place it so that the crowned (convex) side is facing up. This alignment will help keep the board from bowing as it ages. If the board doesn’t have any obvious cupping, look at the end grain. If the grain pattern has a clear curve, place the board so the curve is facing up, like in the picture below.
- Finish the Board
Before putting the new board in place, stain or finish it. Use the same kind of wood as the rest of the decking for the patch. If you don’t paint the whole deck, the patch will stand out from the rest of the deck if you use a different type of wood.
- Install the New Board
Place the finished board so that the space between it and the next board is the same. Drill two pilot holes through each end of the board, 3/4 inches from the end, so that the holes are in the middle of the support cleats. Drill two pilot holes in each of the other joists that the new board will go across. Put two 3-inch deck screws through the pilot holes and into each cleat and any joists that are spanned.