How Long Should Trusses Be?

Basic Short Span Trusses

• Short span trusses are less than 60 feet in length. Depending on the architecture of a particular building and local building codes, trusses can be metal or wood. Typically, trusses spanning more than 16 feet without a wall or other structural support underneath should be reinforced steel. Naturally, the specifics of a roof, including climate control mechanisms or other loads to be installed within the trusses, can affect appropriate length.

Long Span Trusses

• Long span trusses extend more than 60 feet from end to end. Trusses of this length are typically used in large structures, such as warehouses, airplane hangars and shopping centers. Experts recommend trained engineers for long span truss installation, as these components require extensive bracing plans to prevent collapse. Simply installing trusses greater than 60 feet requires specialized equipment to support the added weight of materials.

Bracing Requirements

• All trusses require bracing. A truss can be virtually any length, provided a proper bracing plan is in place. Bracing and cross bracing a truss prevents structural collapse, especially in cases where heavy loads on the structure are anticipated. For example, a simple residential roof uses short span trusses and requires only minimal bracing. However, in areas of the roof where climate control components, chimneys and other heavy loads are installed, additional bracing is necessary to help support the added weight.

Load Requirements

• Every building plan or blueprint specifies loads. Not only do installed components such as air handlers, heating units or chimenys affect truss length, but also choices in roofing materials. A slate roof, for example, needs more support than a shingle roof. Accordingly, the length of trusses, truss slope and associated bracing for a slate roof would be different than a shingle roof of the same square footage.