Q & A: Thatched Cedar Shingle Roof

Justin asked, "What is the waste factor for a thatched cedar shake roof? What little I can find says it should be at least 100%, is this correct?"

Thatch roofs and cedar roofs use different kinds of materials. Thatch roofs use many types of long-stemmed plants, like, wheat and water reed. My first thought, when a thatch roof is mentioned, is a tiki hut type roof where palm tree leaves are used. A thatch roof uses local plants commonly grown on farms and after harvesting, the stalks are bundled and then when laid up on the roof to shed water. These types of roofs have been used for centuries and are still being installed to this day.

Your question, I think, was, using a cedar shake, how do I create the look of a thatch roof and cost it out. First of all, let us understand the difference between cedar shakes and cedar shingles. It is my experience that cedar shingles are used for this look. The cedar shingle is not as tall in length, being only 18 inches, compared to the larger sized cedar shake which is 24 inches. The cedar shingle is also thinner and thus can be more useful for a project like this when bending the shingles over a radius edge.

I dug up an old photo to show what this thatch design looks like. Arguably this roof is compared to a thatch roof as we see in Europe but the materials used are cedar shingles, weaved, waved and stacked to give the home the thatch look. The next photo is a close up look at a thatch design on a steep roof. Here you see the design face of the roofing system.

Cedar shingles are typically run at five-inch exposure and as you can see here every other course has a wave design from a one and a half-inch coverage to a five-inch coverage, then a straight course. Repeating this gives you the thatch look. Using this design gives you a total of six and a half inches of coverage for two-course that normally would be ten inches. That figures out to be a thirty-five percent loss using this repetitive pattern. There are other spontaneous designs that have no pattern and can eat up lots of sqs. of shingles real fast. I have seen that 100 % waste factor used up. I just gave a bid Augs. 15, 2013 to do this exact thing and I costed the job at normal five-inch exposure and then doubled the materials cost plus other expenses, and I feel ok with the estimate, but will only do a job like this for time and materials.

I hope this helped if so, share it with someone.

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