Wood shingles can last between 15 and 40 years. Their durability depends on your climate, their exposure to the weather, and the slope of your roof. As a rule, the steeper the roof, the longer the material will last because rain won’t pool and ice and snow won’t accumulate.

If your roof is leaking, or you suspect you have cracked or damaged shingles caused by a recent severe storm, check your roof for curled, broken, or split shingles.

Wind and rain can erode shingles and cause them to lift from the roof. You can also go into your attic and look for signs of water—either dampness or stains.

If only a few shingles are damaged, you can repair or replace them. But don’t attempt to work on your roof if it is steeply pitched or when it’s raining. Don’t go onto your roof if it’s even slightly damp; instead, work in calm, warm weather.

Limit how much you walk on your roof to prevent causing more damage. If you have any doubts about the safety of going onto your roof, call a roofing contractor to do the work.

A shingle that has lifted from the roof can simply be renailed down and the nailheads sealed with roofing cement. Repair a split shingle by closing the gap between the two pieces, nailing them to the roof deck, and sealing the crack and nailheads with roofing cement.

Cracked, warped, missing, or broken shingles need to be replaced. Here’s how to do this:

1) With a hammer and chisel, split the defective shingle along the wood grain, and pull out as many pieces of the shingle as you can.

2) Slide a flat bar up under the shingle, as shown in the illustration below left, and force out the nails with a few hammer blows. (Or, for a neater job, you can cut off the nails using a hacksaw or a special shingle ripper, available at hardware stores or roofing supply companies). Take care not to damage the roofing material beneath the shingles.

3) Cut a replacement shingle to fit the space, making it 1/2 inch narrower than the space (leaving 1/4-inch clearance on each side so the wood can expand with moisture changes).

4) Tap the replacement into place with a hammer, stopping about 1/4 inch before it is flush with its neighbors and leaving 1/4 inch on either side. 

5) Drive two roofing nails just below the butt of the shingle above it, angled slightly upward. Then place a wood block against the replacement and tap it upward the final 1/4 inch, as shown at right.

 
Another common problem in particularly moist climates is that moss can grow on wood shingles, particularly beneath trees that provide heavy shade. Cutting back tree limbs to encourage sunlight helps eliminate the cause, as does hosing down the roof twice a year. Once it becomes established, moss can be removed by a power-washing specialist using a power washer with hot water and fungicides.