In a previous article, I reviewed some techniques and concerns while operating on a pitched residential roof. Since we respond to multiple building types, we should be aware of the challenges of a flat roof. Firefighters often feel more comfortable on a flat roof simply because its flat. Although most of the operations performed on a flat roof are similar to a pitched roof, flat roofs can hold their own challenges and dangers.
Flat roof construction can play a major factor in the operation and its safety while working. You can find a flat roof on a residential structure, which can be made of two- x six-inch lumber with ½-inch thick or greater plywood decking followed by rubber or metal roofing material. In newer lightweight construction, you can find the preengineered beams and trusses with ¼-inch thick or greater plywood followed by the roofing materials. On commercial buildings, you can find a steel joist with steel “Q” or metal decking followed by a thin layer of concrete or fiberboard, and then foam that can range from ½ to two inches, then rubber roofing material and even those topped with stones.
Some of the common roofing materials are the following:
Built-up roof. The traditional hot tar-and-gravel roof is built from three or more plies of waterproof material alternated with hot tar and ballasted by a layer of smooth river stone. Once made of tar paper, these types of roofs gradually are using more advanced materials such as fiberglass membranes.
Rubber membrane. Ethylene propylene diene monomer (EPDM) is a true rubber. The durable material resembles an inner tube, but it’s engineered to resist damage from sunlight. EPDM can be mechanically anchored with fasteners, ballasted with stone, or glued.
Solar Paneled. This is one of the most common “special-use roofs.” If you gain access to a roof and notice solar panels, consider a second option. If you have multiple properties in your district that have solar panels, consider reaching out to the company that installs them to receive the most recent information on the systems being installed. Special-use roofs can hold another danger. Nowadays, a builder uses every space available to get the most out of the building. You can find roof-top decks, sitting areas, bars, grills, and gardens. These are all built over the top of the original roof construction, adding another layer to go through.
Make the same considerations when you access a residential or pitched roof such as using standard ground ladders, an aerial device, the interior stairs of an attached structure, and walking the roofline. Commercial roofs often have interior or exterior fixed ladders and hatchways that you can use. However, reaching the roof is when things can change. Typical flat roofs will have some type of parapet wall (a low way around the roof). The parapet can range from a few inches to a few feet in height. This is where you may need a second ladder to access the roof. Some aerial devices feature attachments that allow you to securely mount a roof ladder to the end of an aerial to provide access down a parapet wall.
Once you access the roof, consider the most beneficial way to open it. If roof hatches or skylights are available, it is often easier and safer to use those instead of cutting new openings. If your only option is to cut, then consider the material you are about to cut. Chain vent saws and circular saws work best on wood construction.
On flat roofs, consider all the layers you are going to cut. When cutting, equipment you could use includes a shovel to remove any stone that is protecting the rubber roofing material, a utility knife to cut the rubber, a larger blade knife or drywall saw to cut the foam insulation, an ax or sledgehammer to break through the concrete, or a metal or wood cutting saw to cut through the roof decking. Make the hole as large as possible, starting at the safest point ahead the fire, making sure you can finish the opening before the fire reaches your area. Once the hole is cut, you can now use a steel roof hook to push through the hole to clear away any drywall or interior ceiling materials. After you complete the ventilation process, exit the roof with all equipment.
No matter a building’s construction type, we always must remember we are there to do one job: to help move the chemicals, smoke, and heat out of the structure, making interior operations safer for firefighters; this buys precious moments for any victims that may still be trapped inside. As this is being done, the overall safety of operating on the roof will be compromised, and members should exit the roof as soon as possible.
Dennis Walton is a career firefighter for the city of Allentown, Pennsylvania. He is also an instructor for On Scene Training Associates, LLC, a FDIC International H.O.T. instructor, and an a djunct instructor at the Pennsylvania State Fire Academy.