Installing Cedar Shakes
Use these modern methods and materials to create a timeless and durable wood roof.
Synopsis: Cedar roofs, once relatively common, have been on the decline due to the rising cost of cedar and the growing popularity of metal. But the rustic look is unmatched, which is why the homeowners in this article wanted their replacement roof to look exactly like their old one. Remodeler Andrew Grace gives background information on types of cedar shakes and the standards and installation details outlined by the Cedar Shake and Shingle Bureau before walking through the steps to replacing a cedar roof, from laying courses of self-adhered membrane, felt, and ventilation matrix, to setting up the first row of starter shingles, to fitting valleys and capping hips and ridges.
Cedar roofs have become pretty rare in my neck of the woods. The rising cost of cedar and the increased popularity of metal have turned what was once a relatively common roof type in the early 20th century into a boutique option. It doesn’t help that I’m a few thousand miles from the nearest western red cedar tree. But when my customers’ 30-year-old cedar roof started leaking, they were resolute about using cedar again. It was not surprising, since it was the shake roof that drew them to the house in the first place.
Shakes or shingles?
When most people think of roofs, they think of shingles, but that’s not the case when it comes to cedar roofs. Cedar shingles are regularly used on walls, but cedar shakes are more common on roofs. So, what’s the difference? Shingles are sawn on both sides and thinner than shakes. Shakes are thicker, and split on one or both sides. There are two types of wood used for shakes: western red cedar and Alaskan yellow cedar. Alaskan yellow cedar is actually a kind of cypress and is harder than red cedar. Alaskan yellow cedar, although popular on the West Coast, is relatively unheard of in the eastern
The responsibility of deciding the grading standards and installation details for red- and yellow-cedar roofs falls to the Cedar Shake and Shingle Bureau (CSSB). Their manuals for sidewall and roof installations are invaluable resources, and almost everything you need to know about a bundle of shakes or shingles is clearly printed on its label.
Not all shakes are equal
My customers wanted their new roof to look exactly like their old one. We chose Premium Grade Certi-Split handsplit cedar shakes, and specified 100% vertical grain. These “heavy resaws” are made from a block of cedar roughly 1-5⁄8 in. thick handsplit from a 24-in. log round. The block is then resawn corner to corner to create two tapered shakes between 3⁄4 in. and 5/4 in. thick at the butt. “Premium” refers to the percentage of edge grain to flat grain in the shake—Premium is 100% edge grain. There are two types of edge grain that meet the standard: slash grain and vertical grain. Vertical grain is perpendicular to the width of the shake. Slash grain can be at up to a 45° angle at the butt. Vertical grain is more stable, so I specified 100% vertical grain to minimize curling.
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