![]() See IRC 2018 for the testing requirements for all the materials used. Refer to the manufacturer’s details for installation. The self-adhesive membrane should consist of a material like a butyl or acrylic (meeting AAMA 711). For metal or rubber membrane roofs, continuous flashing is an alternative to step flashing. Note that step flashing is typically pre-formed individual metal pieces with 5-inch legs (5 inches high by 5 inches wide) and 7 inches long (referred to as 5 by 7 step flashing or base flashing). For asphalt shingle roofs, the IRC requires the base flashing against the vertical sidewall to be continuous or step flashing that is at least 4 inches high against the wall and 4 inches wide above the roofing underlayment (2018 IRC Section R905.2.8.3). Metal flashing must be corrosion-resistant and at least 0.19 inches thick (2018 IRC Section R903.2.1). The upturned leg of the step flashing is behind the vertical drainage plane (house wrap) on the wall or sealed to it with an adhesive membrane and sheathing tape. The metal flashing pieces are bent at a right angle, with half of the flashing against the wall and the other half interwoven with or underneath the shingles of the abutting roof. Step flashing is used with shingle roofs continuous flashing is used with metal and rubber membrane roofs. Either continuous L-metal flashing or step flashing is used to prevent water intrusion into the wall where a sloped roof intersects a vertical wall. This flashing may also be replaced as a stand-alone retrofit measure or as part of an exterior wall upgrade.įlashing is required at all roof-wall intersections. ![]() When the roof covering is being replaced on an existing roof, new flashing should be installed at roof-wall intersections. Figure 1. The down and out approach to flashing – metal flashing directs water down and out of building assemblies. These water control details are shown in Figures 4 and 5. Flashing should be integrated with roof and wall drainage planes, such as house wrap or building paper, in a shingle fashion where the top layer of the weather-resistant barrier (WRB) or flashing laps over the bottom layer to prevent water draining behind the bottom layer. Metal flashing and self-adhesive flashing tapes protect vulnerable building components and help direct water down and out of the building (see Figure). Flashing is the most underrated of building enclosure components and arguably one of the most important. The most elegant expression of the concept of drainage is flashing. Drainage applies to assemblies such as walls, roofs, and foundations as well as transitions to those assemblies such as lower roofs, porch roofs, decks, balconies, railings, and dormers. The key to this fundamental principle is drainage. The fundamental principle of water management is to shed water by layering materials in such a way that water is directed down, out, and away from the building. See the Compliance Tab for related codes and standards, requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Single-Family New Homes, and Indoor airPLUS. ![]() Department of Energy’s Standard Work Specifications.
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