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Keeping water out of a building is undoubtedly the primary function of a roof system. But one could argue that ensuring a building's roof stays in place during high-wind events is equally important. Let's face it, without a roof, it's hard to keep water out! This blog takes a look at one of the subsets of wind design of roof systems: Wall Zones 4 and 5 and their relationship with roof perimeters.
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Since its inception a roof's primary purpose has been to shelter its inhabitants from the elements, but now the underutilized potential of roof surfaces is being realized. For roofs with large surface areas, the potential for large overburden installations, such as solar, vegetative roofing, or amenity decks can be exceptional. Even smaller roofs can have overburden that make a significant impact on the sustainability goals of a building including: increased energy efficiency, stormwater retention, energy generation, biohabitat restoration, food production, reduced urban heat island effect, and outdoor space.
Roof systems require a number of performance properties, in addition to keeping water out of a building. Those properties include fire resistance, wind resistance, impact resistance, and R-value of the installed system, to name a few.
Specifying the right materials and assemblies for a low-slope roof system to satisfy a building's specific performance and safety requirements can be challenging. Even with design considerations in place, existing resources for finding applicable roof assemblies are limited in scope, functionality, and can feel disconnected. This is where the Directory of Roof Assemblies (DORA®) can help!
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A common question being asked in the roofing industry is whether or not the 2016 version of ASCE 7 is going to increase the design wind pressures acting on a building. The answer is "yes" in many cases. So, the follow up question is "by how much?" And, that leads to the next question, "how much more capacity will roof systems be required to have when wind design follows ASCE 7-16?"
What are the key material properties?In a previous article the use of thermal inertia to slow down heat flux through a roof assembly was discussed. In buildings where air conditioning costs dominate and heating use is relatively low, higher thermal inertia assemblies can potentially improve energy efficiency. This is particularly the case of buildings such as offices that are only occupied during daylight hours. Thermal inertia could delay the transmission of heat into a building towards the end of the day, increasing thermal comfort and allowing facility managers to reduce cooling during the day.
Thermal insulation is an important part of commercial roofing assemblies. As with anything, there are ways to design with and install polyiso insulation — a better way, a best way, and many variations in-between! What may be best in terms of lowest up-front costs, may prove only good or worse over the long-term life of the building.
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VIDEOS FROM GAF
VIDEO ARTICLE
Air Barrier vs. Vapor RetarderWelcome to Episode 4 of The Building Science FAQ series.The Building Science FAQ video series explores some of the technical questions that crop up when specifying a low-slope roof.
VIDEO ARTICLE
Air Barrier vs. Vapor RetarderWelcome to Episode 4 of The Building Science FAQ series.The Building Science FAQ video series explores some of the technical questions that crop up when specifying a low-slope roof.
VIDEO ARTICLE
Air Barrier vs. Vapor RetarderWelcome to Episode 4 of The Building Science FAQ series.The Building Science FAQ video series explores some of the technical questions that crop up when specifying a low-slope roof.
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