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Get Roofed

Last week, I participated in a panel discussion in Boston that was intended to instruct architects and designers, whether currently involved in preservation or not, about how to properly treat the historic fabric of an old house. This approach may seem obvious to those of us in the field, but there are still a lot of professionals out there with minimal familiarity about the tenets of preservation.

We had the usual pictures of horrible lumberyard front doors and replacement windows crammed (with spacers, no less) into the facades of Federal and Victorian houses. I railed about preserving pantries; others chimed in about the beauty of original plaster and clapboards. The panel was mainly comprised of ardent preservationists who were also used to getting their hands dirty as builder-architects – meaning we know what it is like in the trenches as well as in the ivory tower.

Things got feisty about windows. I had a shot of a ca. 1820 house on which the fenestration had been replaced sometime between 1850 and 1870 with two-over-two sash. The moderator of the panel maintained that it was O.K. to leave these, as they were good, old work. I argued that nothing else on the front elevation was post-1820; there was no wraparound porch or Colonial Revival front door; thus, I would replace the sash with authentic twelve-over-twelves. After all, there were only five of them on the façade. We also pondered whether to rebuild the central chimney, which had been replaced with a diminutive brick one when the house was converted to central heating.

For me, the most surprising topic was our discussion about roofing materials. We decried the deteriorating quality of wood (which now seems to last no more than 15 years), and while we all adored a nice slate roof, the challenge seemed to be what to do in the absence of it or what to do on an early house. The panel moved, somewhat as a whole, to declare that the best choice is the lowly triple-tab asphalt.

There was much disparaging talk of “architectural shingles” as they look shaggy and gimmicky and cost a fair amount more. Yes, there’s the promise of longevity (or at least the warranty thereof, should anyone remain in that house for 30-40 years and live to remember where they got them). Triple-tab, we thought, just made a soft, gray plane that did not draw attention away from the architectural detail of the elevations, while the more textured shingles did. By using them, you’re not doing anything irreversible, unless you’re ripping the slate off. Unless wood shingles are mandated, such as in a strict historic district, it is difficult to justify the materials and labor cost. There’s also a huge amount of waste culling the bundles of shake, and that’s not very green.

There’s artificial slate (rather expensive for materials and labor) and actual slate (really expensive for materials and labor), and these are perfect for a 19th-century home but not really appropriate for an 18th-century one. We all kind of looked at each other sheepishly but could not come up with a better solution.

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  1. Gary D Ramsburg
    April 20th, 2009 at 14:29 | #1

    I would opt for the wood shingles. Unfortunately the modern application methods utilized today are the main culprit in the premature failure of the shingles. Wood has been used as a roofing material in America for close to 400 years and the old roofs lasted a long time. Then we started to install them over solid sheathing with asphalt felt underlayment and interweaving. The bottom side of the shingle could not dry at the same rate as the top of the shingle and they start to warp and rot.
    The original application was over open slats of wood that allowed the wood to dry uniformly and did not trap moisture on the underside of the shingle. The wood of choice in the 1600’s and early 1700’s was Eastern White Cedar, but the demand was high and the supply was used up quickly. Other woods such as pine and oak were also used as the white cedar supply was depleted.
    Currently the best material is cypress and if installed over open slats with proper ventilation the material will last a lifetime. If you life cycle the cost of the cypress roof over the asphalt (yuk) you will find that the cypress is a very good deal even though it is very pricy to start off. The main problem is finding a contractor who has enough confidence to install them without all the felt underlayment and interweaving.

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