How to repair vinyl siding
Our three-step guide to replacing a damaged section
2. Position the new section
Next, lift the bottom edge of this upper piece up and away from the wall so you have access to the nails that secure the lower piece. It’s easier to reach the nails with a pry bar, but a claw hammer will work in a pinch. After pulling the nails, slide the piece of siding down to unhook it from the piece below.
Cut the replacement piece to length. Measure between the insides of any trim pieces into which it fits (such as J channel) and subtract 1/2" to allow for expansion (subtract up to 3/4" if you are working in weather below 5°C). The secret to a good job is to allow the siding to expand without buckling.
To replace the piece, simply work it into the trim channel on either end, and push up on the bottom edge to lock it to the piece below. Then, without stretching it, drive galvanized roofing nails into the nailing slots at the top edge at 16" intervals. Centre the fasteners in the slots, and don’t drive them all the way home—there should be a gap of about 1/32" between the head and the vinyl. Remember, you’re hanging the siding, not nailing it down.