Memorial Continental Hall is the original building of the DAR complex in northwest Washington, DC. The marble Beaux-Arts building was designed by Edward Pierce Casey in 1905, and completed in 1910. It was designated a National Historic Landmark for its architectural legacy, but also for its role in history as the host of the Conference on the Limitation of Armaments in 1921.
First, WEI conservators researched the acoustic plaster to determine whether asbestos testing would be necessary. According to archived original DAR construction specifications, the deteriorating product was Akoustolith, a proprietary product used at the beginning of the 20th century that contained cellulose fibers, not asbestos. While cellulose is not a hazardous material, it does swell and degrade when wet.
WEI removed the damaged flat plaster and decorative elements throughout the hall, with particular attention to the arch because of potential structural issues. The original lath was removed because of water damage, but the steel structure was sound. However, because of the thickness of the original plaster and the weight it entailed, the original lath structure was augmented with additional steel supports. The purpose of the new supports was three-fold: to bolster the original frame, to hold the new steel lath, and to reduce the amount of base plaster needed thereby reducing the final load on the arch.
The plastering team used classic techniques to blend the new material with the original ceiling. In flat areas, a new plaster finish coat was trowelled on and finished to match the existing in material and texture. In areas of bas-relief, molds were made of the pattern in undamaged areas; the casts were applied to the new base coat. Seams between the new cast pieces – as well as cracks in the wall – were covered and patched. When complete, WEI coordinated with the DAR in-house painters to schedule painting once the plaster was fully cured.