The Burnett brothers of the San Francisco Chronicle field a lot of roofing-related questions. Case in point, recently, a reader wrote in asking them for tips on how to care for a deteriorating shake roof. Should they repair the 20-year-old one they had or look into a new roof altogether? Before getting into the advice they offered the homeowner, let's talk about what a shake roof actually is and what kinds of problems the homeowner was experiencing.
A shake is actually a type of roofing shingle that is made from split logs. A shake roof results when these wooden shingles are used to cover a house. On the plus side, a shake roof is visually appealing and typically has a long lifespan. On the downside, wooden shingles are labor intensive to install and cost more than most other roofing materials. Therefore, it is to the homeowner's financial advantage not to replace them until their lifespan is up.
Getting back to the San Francisco homeowner who was wondering whether the replacement of a few split or damaged ridge caps (the place where two flat sections of the roofing join together) on the roof by a licensed roofing contractor a while back was such a good idea. Another roofer had suggested that the roof caps shouldn't have been replaced a few at a time but rather should have been done a whole row at once. Which one was correct?
The Burnett brothers weighed in in favor of the "roofer who suggested replacement of the entire ridge cap." Why? Because, they reasoned, the rest of the shake roof had been installed properly, but the ridge cap was "the weak link." Getting it fixed properly, all at once, could, therefore, give the homeowners the extra five to ten years they were hoping to enjoy from their existing shake roof before shelling out money for a new roof. Buying that extra time would mean they'd get the full 25- to 30-year average lifespan out of their wooden shingles.
What may have led to the ridge cap splitting in the first place? The high moisture content that is present in the cedar shaking when it is brand new tends to dissipate as the roof ages. That loss of moisture causes the shingles to expand and contract in response to changing weather conditions. In particular, rain causes the wood to swell while warmth and sun lead the shakes to shrink. Over time, that expansion and contraction causes cracks to form in the wooden roof shingles.
Fortunately, the ridge caps can be replaced without having to replace the entire roof. When deterioration of the shakes necessitates replacement, the Burnett brothers think "the best practice is to replace the entire run." They explained it this way to the homeowner, "Replacing ridge shakes piecemeal will most likely require revisiting the project many times, which invites damaging material that is in good shape. Better to do the job once and right than to continue to replace material that was going to fail anyway."
By following that advice both the homeowner and you could get an extra decade or more out of your cedar shake roof. And that could save you a pretty penny or two.