Project Profiles: Historic Preservation



SHEET METAL CONTRACTOR: James R. Walls Contracting Co. Inc., Clinton, Md. ROOF CONSULTANT: Roof Consulting Services Inc., Glen Allen, Va.

JRWCo reuses old hardware and trim to install the new custom windows.

JRWCo reuses old hardware and trim to install the new custom windows.

Roof Materials

Work on the Library section of the building was completed on the perimeter mansard and included upper and lower built-in gutters, copper wall cladding, cornices between dormers, 26 radius eyebrow dormer cornices, barrel roof covers, and new historically accurate windows and framing.

The first task was mobilization for demolition. A platform was erected to set up a hoist that was used throughout the job. Storage space on the roof and ground were limited because of the urban density. James R. Walls Contracting Co. (JRWCo) Inc. was only able to use one parking space.

Demo began by removing the barrel tops on each of the 26 eyebrow dormers, radius cornice on each barrel dormer face, upper built-in gutter (416 linear feet) and cornices below the upper built-in gutter. Next was the removal of 500 copper cladding wall panels, window flashing around the entire perimeter for each of the 26 windows, the lower main built-in gutter and counterflashing in the stone parapet (498 linear feet). Often, there was only 18 and up to 36 inches between the materials being removed and the balustrade. Material from the demolition had to be carried over the built-in gutters. Bigger pieces had to be passed up to the batten roof, across a flat EPDM roof, down one level and finally taken over to the hoist.

JRWCo began rework but also needed to address the damage discovered during demo. New plywood was installed on the walls, which were previously covered by cladding, and the built-in gutters were patched as needed. There was not funding to redo the batten-seam roof, so JRWCo devised a method using a lock strip to tie in the areas and keep them watertight until the Daughters of the American Revolution can provide funding for a later phase to replace that roof.

Onsite, to get the job watertight, ice and water shield waterproofing membrane was installed over all vertical structures, lower and upper built-in gutters, and tops of all 26 barrel-roof covers. In the shop, fabrication began on a wide-range of copper architectural elements: built-in gutters, window trims, counterflashing, straight cornices (40 sections) and radius cornices. Radius window heads were then assembled in JRWCo’s shop. These came in 14 pieces. Assembly took 12 hours each, and then clips were soldered to the back of each window head in the field to provide additional support when they were hung.

Back outside, JRWCo started from the lowest built-in gutter and worked up. Space in the gutter was extremely limited—insufficient to install scuppers from inside the built-in gutter, which required installation from the exterior of the building, balancing on the 12-inch water table (workers were tied off in accordance with safety regulations).

Next, the counterflashing for the gutters and balustrade was installed and caulked. They installed counterflashing on stone parapet on exterior walls, window sill flashing, and window side and radius head flashing.

Next, each of the 26 windows had to be raised 8 inches by installing new blocking at the bottom of each window so water would no longer enter through the window. Previously the sill was only about 1 1/2-inch above the gutter. Next, expansion joints were fabricated and installed in areas where there was no previous method to accommodate expansion. After that, the copper surround was installed on the inside where the new windows would be installed. Copper wall cladding came next, using 3/4-inch lock cleats, spaced every 12 inches. Each cleat was fastened to plywood with two flathead screws. Panel size was 24 by 28 inches; 500 panels were installed. Next was installation of the radius window-head cornices, as well as straight cornices between the radius window-head cornices. After the cornices were installed, the upper built-in gutter could be installed as it was locked to the cornice.

After the prep work, JRWCo reused old hardware and trim to install the new custom windows; new hardware and trim would not only cost $500 per window but the hardware and trim would have had to be ordered from England. JRWCo trimmed the windows inside and outside with trim salvaged during the demo.

Next, the custom-fabricated roofs on top of the barrel dormers were installed, and JRWCo tied the existing batten-seam copper roof into the new upper built-in gutter and barrel dormer tops. The final rework was replacing the lone roof drain in the gutter system.

COPPER SUPPLIER: Revere Copper Co.

Roof Report

JRWCo and Roof Consulting Services worked in partnership for 11 months, adhering to strict historical and quality specifications while business continued as usual within the facility.

The complex, which is one block from the White House, consists of one city block and is comprised of three sections: Constitution Hall, which hosts concerts, graduations, weddings and other large affairs; Administration, which is located in the center and the smallest of the three sections; and the Library, which is the most ornate of the three sections.

The Library is a 3-story room with a 4,489-square-foot skylight and 3-story atrium. Around the perimeter of each of the three floors, rooms branch off from the atrium. Each room and the hallways are decorated with antiques from the Revolutionary War period. All exterior work on the roof was coordinated with the museum curator to protect all contents and antiquities. Drop cloths were put out by the curators over all furniture and equipment.

During the 6,436.5 man-hour job, there were no injuries, accidents or time lost. Despite exposure to the elements for an extended period, there was no water or other damage to the Library or contents.

The New York-based Copper Development Association Inc. recognized these feats and honored the project with a 2016 North American Copper in Architecture Award in the Restoration/Renovation category.

Photo: James R Walls Contracting Co. Inc.

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