PATH - A Public Private Partnership for Advancing Housing Technology
[IMAGE: Tech Set Title]
Floor Trusses and Headers
New technologies, including Trim-able Open Web Floor Trusses, Insulated Headers, and Steel L-Headers can allow for the more rapid installation of premium building products.
Trim-able Open Web Floor Truss
Open web, or parallel flat chord trusses, represent the predominate type of floor truss used in homes.
[IMAGE: Trim-able Open Web Floor Truss]
They typically consist of a wood top and bottom chord, usually 2x4 material, and wood web materials connected at joints with metal plates. A few manufacturers use steel webs.
One advantage of open web over dimension lumber or I-joists is that the open space between web members allows for easier routing of utilities and ductwork. Open web floor trusses eliminate the need for field cuts for utility installations, reducing the risk of structural damage in the field.
However, truss dimensions must be known in advance to be within fairly close tolerances. Manufacturers and codes generally do not permit trusses to be trimmed or altered in the field.
Fortunately, new trim-able floor trusses now exist. These trusses, which can be trimmed onsite, add the flexibility of allowing the member to be shortened by as much as 12 inches on each end.
Trim-able floor trusses can be shortened by as much as 12 inches on each end.
Insulated headers are similar to Structural Insulated Panels (SIPs), in which two OSB webs enclose a layer of EPS foam insulation. The result is a lightweight header with a thermal break that does not sacrifice structural performance. The headers are straighter and more dimensionally stable than the usual un-engineered header, and less subject to shrinkage and warping that often causes drywall to crack in conventionally framed header areas.
The steel L-header is a new header design that cuts labor time over the C-channel design by significantly reducing the amount of cutting and fastening. Steel L-headers consists of two "L" shaped, light gauge steel angles. The shorter leg of the angle is about 1-1/2 inches wide, and the longer leg ranges from 6 to 10 inches long. The short leg rests on the wall's top track and the longer leg extends down toward the window or door opening. Steel thickness typically ranges from 16 to 20 gauge.
Content updated on 9/13/2005
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