Roof Trusses for Strength and Span

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Roof trusses are engineered to sustain specific roof and wind force loads. Lumber lengths are specified and connector plates are used to tie all members together. After hurricanes ravaged Florida in recent years, building codes were strengthened to keep future damage to a minimum. Officials and builders have learned that keeping the lid on a house means forming a tight bond between the sail-like roof deck and the walls below. That job falls to the engineered roof truss system that holds it all together. Trusses Surpass Traditional Framing Carpenters used to use two-by lumber to frame into stringers and rafters. Engineers and architects now design roof trusses built of 2x4s in triangular configurations that are joined together with metal connector plates. The result is a cohesive roof truss that stands up to state, local, and national building codes. Trusses perform to such a high degree because the lumber is uniform in size, density, and quality, and metal connector plates ensure rigidity at joints. Engineered trusses have been on the building scene for 35-years, a track record that impresses many builders and homeowners. Kirk Grundahl, executive director of the Wood Truss Council of America (WTCA), Madison, Wisconsin, says homeowners can be assured their roof trusses are engineered to exacting design standards nationwide since manufacturers must meet the standards set by WTCA and the Truss Plate Institute (TPI). Sean O’Connor of Robbins Engineering, in Tampa, Florida—designers, plate fabricators, and truss system engineers—explains that roof trusses create a stronger roof structure because they are engineered using CAD (computer aided design) design techniques and computer analysis for worst-case scenarios. “Because every one of the roof trusses are engineered, it literally takes into consideration all the forces acting on the truss from gravity loads to wind loads, seismic loads, and uplift loads,” O’Connor says. Roof Trusses Allow Open Floor Plans Trusses have many pluses, including their overall strength, ability to be placed quickly, and span capability. Since they’re built from shorter lengths of lumber, roof truss systems are typically less expensive to build than roofs with conventional framing. Trusses are engineered to span larger distances than conventionally framed roofs. Since they transmit weight from the roof to the exterior walls, none of the interior walls needs to be load bearing. This opens up interior space and allows for many interior design options.

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