Safe and Stylish Roof Deck Fire Escapes
Fire escapes are somewhat common here in Washington DC. We specifically find many of these external fire escapes on buildings that are multi-family apartment favilities which have often been converted from single residences to multiple separate individual apartments or condos. In those types of cases, the original internal parts of the building will not necessarily have a secondary needs of egress from each area or residence. Those pathways are particularly important and rental unit requirements.
Today we’re looking at a particular fire escape at the rear part of the building that goes from a rooftop deck area, towards the ground. In studying this particular layout and configuration, we will also discuss other parts of the root system which convey and direct water away from the rooftop. You can see that the gutter system meanders around the edge of the roof, not just that a single rear termination location which is typical in Washington DC, but here as well it goes back up from the side of the building.
A portion of the neighbor’s side wall which stands above this roof is clad with a ferrous sheet metal. That particular metal cladding is almost entirely covered with oxidation / rust. It’s likely that this application is many decades old. The chimney at the neighbors side of the building appears to have significant deterioration and areas of spalling.
As you look at the flashing that extends from the edge of the roof membrane, into the gutter, you can see there’s also several spots of oxidation and rust here at this metal flashing. The rust at the drip edge flashing is one particular issue, but the grade of the gutter is also related.
The height and configuration of the flashing is directly affected by the grade of the gutter. A relatively short run of a gutter will not require as much overall great and therefore generally can have a lower amount of total or overall flashing height. In general, gutters should have a minimum slope of at least one quarter inch per layer foot. We would even recommend more, if the overall space and layout allows for a more significant change in grade.
Water will flow by gravity alone, but it has to be unimpeded for that flow to work in a gutter system. In general, particularly long gutter systems can be problematic because it can be more difficult to achieve the total amount of overall grade, in a longer run.
There are multiple different types of roof gutters. Some of the most common types of gutters include box gutters, half round gutters, and built-in gutters. Water tables are technically different but work in a similar type of way, but just to shed water without collection and channeling. This particular style of gutter is a half round gutter with a black paint finish. Many historic gutters were originally manufactured with ferrous metals, but aluminum metals are more common today because aluminum generally has a higher degree of resistance to oxidation and or deterioration related to exposure to water and the natural elements.
The picture below shows several elements with a closer view of the details. This rooftop is an area without a guardrail or fall protection system, originally not intended to be used as a rooftop deck or terrace area. The door still potentially has a use as a secondary means of egress. From this point, someone at the upper level of this building could retreat from a fire or similar type of danger for the door and then down through the fire escape stairway.
In the picture above, you can also see the areas of oxidation, more clearly, at the galvanized ferrous metal drip edge. Ferrous metal is made from iron, steel, or an alloy of those substrate metals. The particular points where the zinc galvanization cover on the drip edge has failed are coincident with areas where the rooftop concentrates and directs water over the drip edge between the low-slope part of the roof and the wall.
When you look closely at the steel or iron fire escape in the picture below, you can see that the surface of this metal structure is also significantly oxidized and rusted. Unlike the galvanized drip edge above, these materials were not manufactured with a zinc protective coating. In most cases is this galvanization like the coating at the metal drip edge must be applied through a dip type process which means that the metals must be small enough to fit into a vat or pool in the manufacturing facility or factory where the application is applied.
Relatively thin sheet metals, such as the metals used in roofing flashings and terminations can generally be manufactured and or purchased in rolled coils. The coils can be treated in smaller equipment areas because the size is relatively compressed. Then during application, the coiled metal can be unrolled and flattened. Structural iron and steel, like the metals used in the construction of the fire escape stairway though cannot be easily rolled and unrolled, and therefore are less likely to be dip-galvanized. Also, the galvanization manufacturing processes that we use today were not available at the time of construction of the majority of the row buildings found here in the historic neighborhoods of Washington DC.
We recommend every building owner in DC who values the longevity of their roof (and their investments) and building use a contractor who values the simple and important principles of proper roof construction like Dupont Roofing DC. Learn more about our company and the proper techniques of working with roofing on historic buildings in Washington DC here on our blog at DupontRoofingDC.com, and you can call us at (202) 840-8698 and email us at dupontroofingdc@gmail.com. We are happy to help and at least talk through options.
