A Call for Fireproof Construction

“The first point to which our attention has been directed was the expediency of erecting a building which should be secure from danger by fire.”
~Congressional Committee on Public Buildings, 1835

Mills’ involvement with the architecture of the early Treasury building proved to be a rewarding transition toward obtaining his commission for the third and existing Treasury Building. In 1833, the Department of Treasury endured a second major fire leaving the building in ruins. Despite the increased cost and lengthy construction of fireproof construction, preventing the further loss of important government documents and property became a priority for a government in a city that recently suffered significant damage from fires. Furthermore, the fireproofing of a new Treasury building was particularly important given the department’s holdings of currency and public records. Congress therefore sought to replace the second Treasury building with one using the newest advances of fireproof technology.

Mills was an obvious choice having established a respectable record for vaulted construction among only a handful of American architects familiar with this technology. He already even sketched the surviving structure of Latrobe’s vaulted wing on the original Treasury building as documentation to the resilience of the vaulted masonry. Given his experience and his powers of persuasion, in 1836 Mills successfully convinced President Jackson to appoint him Architect of Public Buildings, beginning with the commission for the design and construction of the new Treasury building.

Mills employed his knowledge of materials, construction, and design to create the building that is our legacy today. The Treasury building is built entirely of masonry rather than wood, using the groin vaults made from brick for the module. This groin vault is a design of two intersecting barrel vaults based on the arch. Mills’ use of the groin vault used in a building on a large scale was a unique practice for its time. Instead of using lime mortar typically used in bricklaying, Mills’ used a new fast-drying hydraulic cement that allowed the walls to be a narrow 2’-3” wide rather than the 3’-6” thick, typical masonry wall. A hurdle blocking the assembly however, was the lack of masons versed in vaulting construction. Mills proved his versatility, training the masons hired for the project in the vaulting and thus the Treasury’s fireproof vaults were realized. The barrel and groin vaults used for the interior spaces may still be seen throughout the corridors of the center and east wings, a testament to the strength and resilience that characterizes Mills’ buildings.

For more information of Fireproof Construction, see The Fireproof Building: Technology and Public Safety in the Ninteenth-Century American City, by Sara E. Wermiel, The Johns Hopkins University Press, ©2000.