![]() Where the most common roof surface for decades has been the standard 3-tab asphalt shingle, there is a growing popularity in metal roofing. Homeowners are trying to save money and stretch the life of their roofs for as long as possible. ![]() Also note that the roof rafters are not visible due to the thickness of the foam. This is the attic of a home built in 2013. ![]() Sounding may not indicate anything until you punch through the decking with your body. Even if every support member burns out, the insulation can support the entire roof. The insulation is sprayed at least 12” thick on the underside of the decking. They may show limited or no signs of fire from the outside. ![]() These foam-insulated attics are sealed air-tight. This is becoming more frequent, so we’re bound to have to ventilate these roofs more often. While we’re still under the roof, let’s talk about spray foam insulation. Once shingled and trimmed, there's no indication that the cold roof is even there. Note the 4" thick block of foam, the air gap, and the plywood decking. Here you can see a prefab cold roof panel retrofitted to an existing roof. Steel trusses supporting a pitched roof decked with a cold roof system.Ĭold roof system on a steel-trussed pitched roof. Again, after the roofing is laid, there is no outward indication that the roof might pose any issues to firefighters. These cold roofs can also be made of prefabricated panels that are retrofitted to the existing structural decking. The idea is to allow airflow under the roof decking to aid in cooling the attic space during the summer. Cold roof systems often involve a corrugated metal deck over the roof trusses, with layers of insulation capped off by normal wood decking a architectural shingles. Cold roof systems are becoming more popular for residential roofs. Steel trusses or TJI beams instead of rafters are possible. Then there are construction methods that one would not normally predict on a residential roof system. At a glance, these rafter tails can look like the edges of legacy roofs with 12” or 16” rafter spacing, when they actually have 24” spaced trusses under the roof. Likewise, new truss roofs can have false rafter tails. Old and new conventionally-built roofs can have ridge vents just like truss roofs. The age of a home cannot be used as the sole size-up of the roof. A 2007-built, 2-story home with TJI floor joists and a traditional ridge & rafter roof, pictured below. I would like to point out that even today brand new houses are being built with legacy construction. Over the years, however, I think many books, periodicals, and instructors have led students of the fire service to believe that anything built after the advent of trusses WILL be made of trusses. as early as the 60s, with widespread use coming about in the 70s. We know that trusses came into use in some areas of the U.S. We know that the wood itself is different, as is the way that wood is put together. We all know the difference between traditional ridge & rafter “legacy” construction and truss construction. I’d like to talk about some new and old roofs, how they can trick vertical ventilation crews, and how we can avoid some of the tricks before they cause unexpected problems.įirst off, let’s talk about basic construction types. With today’s engineering capabilities and ever-changing building construction technology, residential pitched roofs are starting to look a lot different than those that we were venting even five years ago. Difficult roofs aren’t new commercial flat roofs have long been a tough cookie to crack, with an infinite number of roof material combinations and challenges that pop up right in the middle of the cut. Even today, the process hasn’t changed, but the difficulties encountered while completing the task have multiplied. It used to be that ventilating residential fires was pretty straightforward.
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