Regular readers will have noticed our absence last week. Unfortunately our roof is in rough shape and required immediate repair. The original plan was to use wood shingles made by hand here on site. I discussed the ins and outs of this process in a blog post a few weeks ago as well as the economic and ecological considerations of wood roofs versus asphalt shingles.
We live in a historical district and run our external modifications by a local and state review panel. One problem the state office saw with our plan was replacing our sawn shingles with hand-split shakes, as these have a different appearance. The state asked us to use sawn shingles instead, so the ones I split by hand will have to be used on the chicken coop I’m building this fall.
The wooden shingles we bought have a higher carbon and ecological footprint than the hand-split shakes we planned to make, but over their 30-year lifetime and disposal, they will still be a better choice than asphalt. Case in point is the giant pile of mulch we’re creating out of the old, rotten shingles. The tag found under the old shingles identifies them as 3rd grade, untreated shingles, meaning they are just plain cedar and appropriate for the mulch pile. We still won’t use them to mulch food crops out of an abundance of caution, but at least they won’t have to enter the waste stream like asphalt shingles do.
Unlike asphalt shingles, cedar shingles must have room to breathe below them, thus we had to build up “skip sheathing,” as per the Cedar Shingle Bureau’s recommendations. This is essentially 2-×-4-in lumber laid over the sheathing above the rafters, with 1-×-4-in boards nailed horizontally. This gives the cedar shingles ventilation below to dry out more quickly, prolonging their life. This was not done on the previous installation (where the shingles were simply stapled onto the decking over an impervious membrane — something not recommended by the Cedar Shingle Bureau), and the shingles were severely rotted after no more than 20 years.
An alternative to the labor-intensive skip sheathing is something called “cedar breather,” which is a mesh that creates a gap between the decking and the shingles. The problem is that this material has not been around long enough to know if it will hold up to 30 years of abuse. One anecdote I found on a carpenter forum came from a roofer who said that he’d torn off a few roofs with this material and the shingles were wet and rotting, but he’s never seen that happen with skip sheathing.
We tried to find FSC-certified wood for this sheathing but had to settle for SFI instead, which is less stringent and industry-policed instead of being an independent organization.
Over the next few days, I’ll detail some of the installation techniques I am using, in case anyone out there decides to install their own roof. I’ll suggest that you block off quite a bit of time, as this is a slow process that takes considerably longer (and slightly more skill) than an asphalt roof.
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