In a recent article, part of three-part series, we took a look at several different types of mansard roofs, typically found at Capitol Hill and Washington DC type rowhomes
Read – Mansard Roof types – Part I
Read – Mansard Roof types – Part II
Anatomy of a Mansard Roof
The row buildings in the photo below have an original slate roof tile at the Mansard roof. The aesthetic value of these buildings is immense. They should be considered historic treasures which should be protected and preserved, but with any mansard roof, maintenance is complicated and expensive. There are several parts of a Mansard roof system that are relatively unique and require special care and historic upkeep, maintenance, and restoration.
Each course of roofing tile or shingle must be flashed into the sides of a dormer where the dormer walls interface with the roofing. The top of the mansard is covered with a ridge cap, similar to a coping metal found at a typical parapet wall, but in this particular case, the metal is formed with a radius shape to provide an additional aesthetic detail and value. The water table ()or built-in gutter) below the dormers, at the bottom of the mansard roof is complicated in a few different ways. The water table must be properly flashed to have a membrane that continuously extends above the bottom few courses of the mansard roof and is flashed in succession, under the window flashing of each respective dormer. As well, drainage from the water table or built-in gutter requires a concentric outlet, similar to a typical gutter, but in this case the downspout has a different historic aesthetic and is generally round whereas modern downspouts often have a rectangular shape.
The dormer at the left side of the mansard is a gable style, similar to some of the dormers shown in the last, most recent article, but the dormer at the right side has a radius, similar to a corner turret of many historic and particularly classic row buildings.
Added elements and why less is more
Although many people, specifically including our company, value and respect the historic details of mansard roofs, because of access requirements and supply chain limitations reducing material availability, it’s more difficult and particularly costly for many of the repairs and upkeep needed related to mansard roofs.
During the recent pandemic, prices for semi-precious metals such as copper have increased substantially. These materials are used and required for historic roofing elements where visible from the exterior of the building, particularly at water tables and aesthetic trims form mouldings and cornices.
The picture below shows two near identically built row buildings, side-by-side. Both buildings have beautiful architectural details, but both are in significant need of restoration and upkeep. The building on the right side has been carefully cleaned in more recent decades, but even now again shows signs of oxidation from ferrous metals above, in areas that follow drip trails, and the building to the right has not had an extensive overhaul in at least several decades.
Maintaining a Flat Roof System
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, contact us or fill out the webform below and drop us a line. We will be in touch if we can help.
