Looking Behind A Historic Water Table – Part I

We often look at the front of facades of historic row buildings in Washington, DC and Capitol Hill and think about the overall aesthetic, in terms of classic architecture, but we don’t often think about what the water tables or roof cornices are built from, at the tops of the front facades.  The water tables are like small roofs.  The water tables and or build in gutters project away from the front building facades.   This intentional projection creates a cover or small roof that protects the portions of the front facade of the building below from windless rains. Often, rain will be coincident with heavy winds, but just as often, many precipitation events have relatively low or no wind. In those conditions of low wind with precipitation, the majority of the facade can be protected from hydration and exposure precipitation by a projecting ledge, cornice, or water table, in this case. 

metal support frame

Historically, these projections, made from sheet metal, wood, or even masonry were used to safeguard building facades from some degree of water exposure. Water tables are architectural elements, resembling miniature roofs.  They serve as protective ledges positioned at or near the top of the main building facade or attached structures such as porch or portico roofs.   This strategic placement aimed to divert rainwater away from the walls, mitigating the adverse effects of moisture exposure. By functioning as barriers against moisture, these water tables effectively deterred water-induced deterioration.

water table
In this photograph, you can see the neighboring house across the alleyway with the water table still intact, for comparison

Often constructed from materials such as copper or ferrous alloys, the sheet metal ledges were shaped and attached to the facade to protrude, as an edge from the building. This overhang configuration served as a preventative measure to obstruct the brunt of rainwater. In essence, these ledges acted as a defensive canopy, guarding against the degree of infiltration of water and its potential deleterious consequences.

The consequences of moisture infiltration are well documented, right here on our website and also another locally based site called Infinity Design Solutions. Building materials like bricks and mortar have some degree of moisture tolerance or resistance but especially historic masonry has a certain absorbent quality, rendering them susceptible to water absorption. As moisture permeates these materials, it prompts structural degradation starting with deterioration of the inherent cementitious binder but later leading to additional damage such as cracking, breakage, and erosion. Freeze-thaw cycles are particularly problematic with the expansion of water due to freezing in our winter colder climates, exacerbating the physical stress endured by these materials.

water table intact
In this photograph, you can see the neighboring house across the alleyway with the water table still intact, for comparison.

Smart proactive replacement, construction, upkeep and maintenance of low slope roof and mansard roof systems requires an enthusiastic interest and understanding of historical methodologies, waterproofing principles, and building science.   Here in Washington DC, historic and modern residential and commercial buildings are extremely expensive and the roof and related systems provide the shield that preserves the building. 

We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the value of quality construction and building maintenance, and develop a relationship with our company.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the roof and related systems of your building in Washington DC, fill out the webform below and drop us a line, it’s quick and easy.  We will be in touch if we can help.

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