To repair cedar clapboard siding, remove the damaged pieces and vertical caulk joints, section out the damaged clapboard, patch any damage, install new cedar clapboards and paint. Repairs can be completed over a weekend and require cedar clapboards, pressure-treated wood, nails, epoxy, oil primer, paint, latex caulk, a paint brush, paint tray, nail set, hammers, saws, a utility knife, chisel, drill and a sledgehammer.
- Remove damaged siding and vertical caulk joints
Determine which cedar clapboards are rotted. Remove these using a chisel. If there are vertical caulk joints between the end boards and siding, score them with the utility knife, causing them to crumble away.
- Section the damaged clapboard siding
If only part of the clapboard is damaged, section it off with a square, and use a circular saw to cut away the damaged portion of cedar clapboard.
- Patch the remaining siding
If necessary, use a reciprocating saw to cut out any damage caused by termites. This leaves a hole under the siding. Measure this hole, and cut out two pieces of treated wood to that dimension to create a patch. Nail the two pieces together, and use a sledgehammer to fit the patch into the hole. Drill holes in the surrounding wood, and fill the holes with epoxy, thus strengthening the remaining wood.
- Prepare to install new cedar clapboards
Apply oil-based primer to the back of the new cedar clapboards to prevent future insect damage. Nail 1-by-4 strips of treated lumber to the lowest sill where the siding is going. Measure the amount of siding needed, and cut the clapboards to these dimensions.
- Mount the siding
Starting from the bottom, nail the clapboards to the strips of treated lumber. Add further courses of siding by slipping them under the courses above them. Nail each into place, then caulk the end joints.
- Prime and paint the cedar clapboards
Apply primer to the front of each cedar clapboard, and allow it to dry completely. Paint the siding to match the rest of the house.