Q: We are trying to decide how to proceed on a possible roof repair. Our shake roof is a little more than 20 years old, and one roofer said he thought it would last five more years.
A few years ago we had a handyman replace a row of ridge caps that were missing or broken. We noticed recently that some more ridge cap shakes were split or damaged, and we contacted a licensed roofing contractor to replace these.
He only replaced a few ridge caps in each area instead of the whole row. He also nailed down some of the older caps that were split next to the shingles he replaced.
We spoke to another roofer who said that it is not good to replace individual ridge cap shingles. He said the whole row should have been replaced. This contractor is going to take a look and give us a bid on replacing all the ridge caps.
Which of these approaches is correct? How do we know when we need a new roof and what kind of repairs are needed to prolong the life of our shake roof?
A: You’ll know you need a new roof when it starts to leak. Take a trip into the attic each year after the first good rain and look for signs of water stains on the sheeting (the wood that is attached to the rafters). If you see signs of water, the roof is about dead.
You’ll probably be able to have the problem area patched, but that will be only a short-term fix — a new roof is in your near future.
Although both are almost always cut from Western red cedar, the terms shake and shingle are not interchangeable. Shingles are thinner than shakes and are smooth-sawn.
Shakes are thicker and may be smooth-sawn for a more formal look or hand-split for a more rustic look. In a roofing application, shakes will last at least 50 percent longer than shingles.
We agree with the roofer who suggested replacement of the entire ridge cap. Here’s why: The ridge cap — the point where two flat sections join — is the weak link in an otherwise properly installed shake roof.
Kevin has a taper-sawn shake roof on his house. It’s a gable roof on both the garage and the main building. The roof is 15 years old and mostly in great shape. But the ridge cap needs some help.
When a cedar shake roof is brand-spanking new, the wood has high moisture content. As the roof ages, the shakes acclimatize and lose moisture. They expand and contract with the weather.
In the rainy season the wood swells; in the hot summer sun the shakes shrink (say that 10 times fast).
Eventually, the movement causes cracks in the shakes. In addition, exposing the surface of the shakes to the ultraviolet rays of the sun causes decomposition and the shakes lose some surface over time.
The average useful life of a cedar shake roof is 25 to 30 years, depending on the climate, although we’ve seen some last as long as 50 years. This longevity is due to the natural decay resistance of cedar and the roof application process.
Cedar naturally contains tannins that resist fungus and insects. As to the application process, when properly done, each course of shakes is interwoven with roofing felt, which creates a three-ply wood roof with tarpaper between each ply.
On gable, gambrel or hip roofs, the point where two flat sections of roof meet is the ridge. While the rest of the roof consists of layers of flat shakes, the ridge is made of two shakes stapled together and overlapped to cover the point where the two sections of roof meet. The joint where those shakes are stapled together is the weak spot.
Over the years, with the inevitable expansion and contraction, the ends of the shingles crack and the staples fail. When this happens, there’s a fair to middlin’ chance the roof will leak at the ridge.
When ridge cap pieces become so deteriorated they need replacement, we think the best practice is to replace the entire run. Replacing ridge shakes piecemeal will most likely require revisiting the project many times, which invites damaging material that is in good shape.
It’s better to do the job once and right than to continue to replace material that was going to fail anyway.
