Vinyl siding

A zip tool will unlocking vinyl siding seams to access to the nailing strip. (June 14, 2010)

House siding is like tree bark — a tough exterior skin that takes a beating to protect thinner-skinned materials inside.

But there are so many sources of damage. A stray baseball puts a major league dent in your aluminum. Gutter leaks rot your wood shakes. A woodpecker bores holes in your cedar. Blistering sun buckles your vinyl. If only siding could repair itself the way tree bark does.

Until that self-sealing or nearly indestructible material arrives — cement-based clapboards come the closest for now — try these solutions.

They're not foolproof. But they beat the time and cost of re-siding by a mile and are worth a try.

Aluminum: The most common problems are scratches and dents. On scratches, sand or steel-wool the edges, even if it exposes a bit more metal. Coat with rust-resistant metal primer, and finish with an all-acrylic exterior paint. Try to contain the paint in the trough of the scratch, say, by using an artist's brush. You don't need a perfect color match — just close enough to keep the repair from standing out.

On dents, you could prep the surface, fill the depression with automotive body filler, then sand it smooth and paint. Or try one of the suction-type repair kits. They're mainly used to pop small dents out of car bodies, and have the strength to do the same with most aluminum siding.

Vinyl: Cracks and punctures (often caused by stones thrown from a lawn mower) are the main problems. Gluing on a patch may look OK from a distance, but often calls more attention to the spot by creating extra seams.

The best solution is to replace the panel. Do that by unlocking the seams at the top and bottom of the damaged piece — below simply to free it, and above to gain access to the nailing strip. You'll need a zip tool, like the Malco Sideswiper (about $5).

Wedge it into the seam, and pull down and out as you slide along the seam, unzipping the connection. Then snap the bottom of the new panel in place. With the top seam still loose, you can nail through the perforated strip on the new piece, centering nails in the slots, and leaving the nail heads raised so the siding can shift.

Finally, use the zip tool in reverse to re-zip the top seam.

Wood clapboards: Small defects can be scraped, sanded, filled with exterior-grade putty, then primed and painted. If nails have popped and the piece is loose, drive a longer nail in the same hole, or a screw for more holding power if the piece is twisted.

Fix splits at the ends of boards by opening them just enough to force in some exterior glue. Then nail or clamp the board to close the seam, and wipe off the excess glue before it hardens.

There is no zip tool for wood. You have to pry up the covering clapboard, then pull or cut nails holding the damaged piece.

It may help to split the damaged section down the middle and remove it in pieces.

Wood shakes: To replace a damaged piece or two, pry up the shakes above and hold them away from the wall with a wedge.

If the damaged shake is split you can probably pull it out in pieces. If not, use a chisel or a screwdriver to split it into removable sections.

The tricky part is pulling the old nails without splitting the good shakes that are wedged above. If you can't pull them, use a hacksaw blade to cut them flush. Finish by tapping the new shake in place and securing it with a couple of nails driven at an angle just under the edge of the shakes above.