How to Repair Split Clapboard Siding How to Repair Split Clapboard Siding

What You'll Need
Level
Crowbar
Hammer
Ring-shank nails
Lumber for new clapboard
Cross-cut saw and sawhorse
Tape measure
Square
Pencil
Caulk

Clapboard siding is one of several terms used to describe overlapping layers of wedge-shaped boards that protect the wall frames of a house from the elements. The style is especially prominent in New England. The boards are layered from the bottom to the top of the building and nailed into place like shingles. Older construction used wood for clapboards; today plastic and metal materials are common as well. Replacing clapboards requires a careful hand and accurate cutting, so regular maintenance will save your time. Keep the clapboards painted to protect them, and replace splitting or rotting clapboards immediately before the damage can spread.

Step 1 – Pull Out Bottom of Old Clapboard

Inspect the exterior walls of your building and flag all the split clapboards for removal. Stick the pointed edge of the crowbar under the bottom lip of the split board. Drive the crowbar into the gap by tapping it with the hammer. Pry up the board with the crowbar. Pull the crowbar out and use it to remove the nails holding the bottom of the board in place. At this point, you can gently split the clapboard along the fracture seam and discard the fragments. The top portion of the clapboard will be nailed under the bottom of the clapboard above it. Take care not to damage the upper clapboard or you will double the scope of the repair job!

Step 2 – Pull Out Top of Old Clapboard

Pry the top board up slightly. Tap the crowbar into each nail and bend it slightly outwards. Now, hammer the top board back down and the nails should pop through it. Now you can use the crowbar to remove the nails through the top clapboard. Reach under the top board and wiggle out the remaining fragments of the split bottom board.

Step 3 – Cut New Clapboard

Measure the dimensions of the opening and cut a new piece of clapboard. For best results, purchase boards of the correct width and thickness from a hardware store. Mark the desired length of the gap on the replacement board with a tape measure and square. Lay the board on the sawhorse and cut it with the saw. Don't push hard when sawing; let gravity do the work.

Step 4 – Install New Clapboard

The side of the new clapboard that you cut through will not be primed, so lay a bead of weatherproof caulk on the side of it. Although the overlap of the boards protects the vertical sides, the horizontal seams are vulnerable to moisture. Caulk the sides of the intact clapboards adjacent to the opening you are repairing. Slide the clapboard into place under the row above it, and level out the bottom. Fasten the clapboard into place by driving ring shank nails into the top and bottom at a downward angle. Repeat the process with each split board. Prime and paint the repaired area to color match, or repaint the entire wall if necessary.

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