By John Grogan
Many challenges must be faced in the design and construction of commercial buildings. One limiting factor is the length of ceiling span that can be accommodated without supporting structures such as columns and interior walls.
As building owners and users know, interior structural elements disrupt the flow of activity in a space, create fixed points around which uses must be planned, and can visually mar an otherwise attractive design.
Warehouses and other industrial buildings that require extensive open floorspace have dealt with this problem for years by using open-web roof trusses. These trusses are pre-manufactured with top and bottom sections (chords) made of wood with a network of tubular steel members (webs) installed at an angle between them. With more types of profiles for open-web trusses available in today's market, A&D professionals are incorporating them into stores, offices, schools, libraries, and other public and commercial buildings. In schools, open-web trusses are often found in gymnasiums, auditoriums, cafeterias, and other common-use areas.
For buildings with exceptionally long ceiling spans (more than 100 feet), open-web trusses are an ideal solution. Their high strength-to-weight performance allows long spans with fewer supporting structures. For other building applications where design flexibility or economy is desired, open-web trusses work equally well.
Today's open-web trusses are available in numerous configurations, allowing architectural freedom and a range of aesthetic options. Truss profiles include straight, tapered, pitched, scissor, barrel, and parabolic, among others. In addition to creating greater flexibility in the shape of roofs, designers are increasingly using open-web trusses as design features in exposed ceilings. They provide ceilings with an open, light, and airy appearance, and allow for easy routing and placement of ducts, wires, lighting fixtures, and other utilities. In addition, they add the warmth and feel of wood.
Open-web trusses are lightweight, stable, and easy to install. Pound for pound, they are among the strongest structural components available. They are typically custom-manufactured to an individual project's specifications. In some products, the top chord is made from engineered wood, which can provide exceptional strength and splitting resistance.
In addition to strength and design flexibility, open-web trusses are also a cost-effective choice. Commercial buildings are often built under very tight budgets; structural elements can be a significant portion of project costs. The variety of truss depths and different configurations of tubular steel webs helps professionals specify an open-web truss that meets load-bearing requirements while reducing the amount of materials needed. Some manufacturers' products are also recognized for use in educational facilities and commercial buildings by major building codes, which can mean fewer delays during approvals and inspections.
John Grogan is the commercial business development manager at iLevel by Weyerhaeuser (www.iLevel.com), Federal Way, WA. More information can also be obtained by calling (888) 453-8358.
