With the purlin/bracing installed, the long rafter span would be broken into two shorter spans, thus allowing the rafter to carry additional load.īefore you decide on lumber sizing and span, consult your local building code officials to determine design loads for your area. This PDF document provides detailed information on the product features, benefits, specifications and installation guidelines, as well as span tables for various load cases and scenarios. No matter where they’re used, they install quickly with little or no waste. They can easily be built-up on site to reduce heavy lifting. You can break up a long span of rafters by installing a purlin and bracing on the underside. SmartLVL 15 is the latest innovation in engineered wood products from Tilling Timber, offering superior strength, stiffness and durability for a range of structural applications. Microllam LVL beams work well in applications all over the house. When calculating the span of joists or rafters, use the horizontal distance between vertical supports. The number 1 grade material is more expensive than the #2 grade, but if you can use fewer or smaller number 1 grade joists or rafters in your design, you may actually save money.ĭepending on the availability and cost of various size framing materials, it may be more economical to use larger joists or rafters in your design because you can typically use fewer of them. Span Tables Index of span tables í ì Scope of this publication This Design Guide and Load Tables assist in the selection of SmartLVL® í ð- beams for most of the common structural ar-rangements met in domestic construction. For example, you can span a #1 grade (no knots) southern yellow pine joist a greater distance than a #2 grade of the same species (with knots). The lengths and sizes of joists vary depending on the species and quality of the lumber used. To calculate maximum spans of additional species of lumber, use the Span Calculator or the Span Tables for Joists and Rafters on the American Wood Council website.Ĭonsiderations when using the Rafter and Joist Span Tables Contact your local building code officials to determine the building code for your area. Weigh all of the elements when designing wood structures. Some areas have wind and seismic conditions. For example, some localities get large amounts of snow, whereas others get none. Load Tables, use FASTBeam software, or contact Georgia-Pacific Engineered Lumber Technical Services. Before determining the maximum spans for joists and rafters, you must know the load requirements for your region.
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