Craftsmen from The Historic Roofing Company have been working diligently since the beginning of the month to replace the well worn wood roofing system on The Hilleary-Magruder House. Installed during the 1980 restoration, and now over 35 years old, the system has held up amazingly well, a testament to quality specifications, materials and installation. With few exceptions the roof has kept bad weather out as intended for even a bit longer than expected.
The roof is composed of what is called a 4-layer wood shingle system. Using 24″ vertical grain western red cedar “Royals,” the roof essentially has a extra layer of protection as opposed to a more typical 3 layer roof of the same material using 18″ perfections. That, in combination with the traditional open roof sheathing has allowed the system to breath and maintain equilibrium far better than a hybrid approach common today in wood roof shingle systems. As this is a restoration project (replace-in-kind) the system will be replaced using the specifications from the 1980 restoration by James T. Wollon, AIA, since it performed so well. During the demolition reconstruction we documented some areas of particular interest and/or concern for evaluation and treatment.
The process began with a visual inspection of the roof structure to determine any soft spots in the system which might present a safety concern for the workmen. A few rafters and sheathing areas were flagged as potential areas of concern, mainly where cracks or excessive sagging was observed in the structure and where spotting from rainwater leakage was detected. Close inspection of flashings at walls, dormers and roof penetrations was also performed.
Since the roof is gambreled (it has two pitches on each side with a break in between), the main roof replacement process was broken into four phases: 1&2 tear off the old shingles and replace the top sections of roofing on each side (including flashings around the chimneys), and 3&4 tear off and replace the lower half of each side (including, the 6 dormer roofs, valley, sidewall and sill flashing). A 5th phase of the roofing replacement includes repairing all of the associated trim, and finally the lower porch roofs and trim must be similarly treated.
This work all has to be carefully coordinated with the masons working on the chimneys and the carpenters restoring the dormers so a water tight envelope is maintained during the process and so that the flashing details are correctly completed.