How do I replace a damaged piece of vinyl siding?

Replacing one damaged vinyl panel is a small job that does not need the wall taken apart. Vinyl courses lock together, so you release the panel above with a zip tool, take the nails out of the broken one, slide a new panel in, nail it loosely, and lock the upper panel back over it. Where the damage is within reach from the ground, plan on about an hour.

Before you start

Check the warranty and the cause. Some siding warranties are voided by do-it-yourself work. Alside's warranty, for example, says any removal or disassembly of components, unless part of an authorized repair, voids it,^[2] and it covers hail damage for replacement materials only, after you first go to your homeowner's insurance.^[2] If the house was re-sided recently or a storm did the damage, make that call first.

Find a matching panel. Match the brand, profile (single, double or Dutch lap) and colour. Look for leftover cartons, old paperwork or the installer's invoice, and take a broken piece to a siding supplier. Even a perfect match will not look identical: Alside notes that replacement panels may differ in gloss and colour from the originals because of weathering.^[2]

Get the right nails. Use corrosion-resistant siding nails long enough to penetrate at least 3/4 inch into the nailable base behind the panel.^[1] Wear safety glasses for all cutting and nailing.^[1]

How the panel comes off and goes back

Each panel's bottom edge hooks onto the locking strip of the panel below it, and its nails sit in the nailing hem along its top edge, hidden under the next course up. That is why the zip tool matters: slip the hook of the tool under the end of the panel above, catch the back lip of the lock, pull down and slide it along the length of the panel. The course above pops free and can be bent out gently, which exposes the nails you need to pull.

When you cut the new panel, score the face with a utility knife and snap it: scoring without cutting all the way through lets the panel bend and break off cleanly.^[1] Tin snips also work. When the new panel goes up, push it up from the bottom until the lock is fully engaged with the panel below, then fasten it without stretching it.^[1]

Nail it so it can move

Most failed repairs come from nailing vinyl like wood. Vinyl siding expands and contracts as the temperature changes, and installed panels must move freely from side to side,^[1] so the panel has to hang on its nails, not be pinned by them.

• Nails go in the centre of the slots, driven in straight.^[1]
• Do not drive them home: leave about 1/32 inch, the thickness of a dime, between the nail head and the vinyl.^[1]
• Space them 12 to 16 inches apart.^[1]
• Nailing too tightly is the first thing to avoid, because it pins the panel and it buckles as the temperature changes.^[1]
• At the ends, leave 1/4 inch of clearance at openings and accessory channel stops, and 3/8 inch if you are working below 40°F.^[1]
• Where two panels lap, overlap them by about 1 inch,^[1] and lap them away from entrances and the point of greatest traffic.^[1]
• Do not face-nail through the panel, and do not caulk laps or the joints at corner posts and J-channel.^[1]

When the new panel is nailed, slide it side to side by hand. If it will not move, one of the nails is too tight. Then run the zip tool along the bottom of the course above and press the lock down over the new panel until it snaps along its length.

Look behind the panel while it is off

With the panel out, you can see the wall. Manufacturers call for vinyl siding to go over a continuous water resistant barrier to stop the intrusion of incidental water,^[1] so the house wrap or felt and the sheathing behind it are what keep water out. Torn wrap, dark stains, soft spots or a damp smell mean water has been getting in, and new siding should not go over rotting wood. Fix that before the new panel goes on.

Permits

For a repair like this, usually none. Virginia's Uniform Statewide Building Code says no permit is needed to replace any amount of siding on houses in residential Groups R-3, R-4 and R-5 outside areas where the design wind speed is above 100 miles per hour.^[3] The exception: a building official may require a permit for replacement siding in a locally designated historic district.^[3] If your house is in one, call the building office before you start.

Stop and call a pro if

• You need a tall ladder to reach it. Second-storey and gable panels are a job for a crew with staging, not a homeowner leaning off a ladder.
• The sheathing is wet, soft or rotten, or water stains run down inside the wall. That is a wall repair, and the source of the water has to be found.
• Several courses are wavy or bulging. That usually points to an installation problem across the wall, not one bad panel. See why vinyl siding buckles.
• The panel melted or warped near a grill, window reflection or other heat source, since the cause will warp the new one too.
• The damage is around a window or door, the electric meter, a light fixture or an outlet, where trim, flashing or wiring is involved.
• The panel is not made any more and you are weighing new siding for a whole wall. See what new siding costs in Virginia.

Related answers

To keep the new panel and the old ones looking alike, read how long vinyl siding lasts and how to care for it and how to wash vinyl siding without damaging it. Hiring for a bigger job? Start with what to look for in a siding contractor, browse siding businesses, find exterior pros around Blacksburg, or see all exterior answers.

If the repair is out of reach or bigger than one panel, describe the siding repair once and licensed local businesses will quote it.