Goals and Mainstreaming
This Tech Set shows you how to increase the durability of a building envelope, which in turn decreases maintenance costs. Six overarching goals that this Tech Set helps to achieve are listed below. However, in order to achieve these goals, some of the technologies need to become more mainstream.
- To decrease both the cost of construction and maintenance costs of a house by promoting effective systems integration of the foundation and frame.
- To reinforce best practices, such as redundant exterior barrier systems (flashing and weather resistant barrier), elevation designs that shield the envelope from elements (roof covering at door openings), and the use of mechanical flashings (rather than caulk) at exterior cladding/trim/roof abutments.
- To keep air and liquid moisture from penetrating the walls of the above-grade structure while allowing moisture vapor within the home to move through and out of the wall.
- To minimize energy lost to infiltration.
- To eliminate structural degradation due to excess moisture within the wall cavity.
- To enhance indoor environmental quality by managing moisture.
Although all of the technologies and techniques listed have proven benefits, some of the recommendations have yet to receive mainstream acceptance. In this section, PATH suggests a number of steps that need to be taken by manufacturers and building industry professionals to help mainstream specific components.
Manufacturers and SIPA should standardize panel details.
Prescriptive methods for designing and building with SIPS should be developed and introduced into model building codes.
Manufacturers need to perform more research and testing on fastener withdrawal at greater spacing, or fastener performance with 7/16" embedment in plywood or OSB sheathing. Currently, most manufacturers of wood, vinyl, and fiber-cement horizontal siding products specify that fasteners should be imbedded into the wood substrate 3/4" to 1¼" at intervals no greater than 16". This means that wall studs are the only appropriate members for attaching cladding because it suggests that securing the cladding to the sheathing provides inadequate fastener embedment. Some products, like Certainteed's fiber-cement Weatherboards
, contain fastening schedules for alternate conditions in the ICC Evaluation Service Legacy Report, rather than the installation instructions.
Manufacturer's recommendation for the attachment of cladding, trim, and architectural features, with respect to the spacing of the structural members, could limit the practice of optimum value engineering (OVE). Once fastening schedules are better defined for the method and (wind/seismic) region of construction, these should be provided in simple-to-interpret literature on a Web site and with the material packaging.
Content updated on 12/7/2005