Attic Truss Load Rating

They have not been updated for the change in lumber values within the last decade.

Attic truss load rating.

Alpine truss designs are engineered to meet specific span configuration and load conditions. This translates into a uniform load of 640 plf across 2 5 ft of the span. If unbalanced snow loading isn t required or specified the truss designer may enter the 25 psf snow load as a top chord live load tcll set the load duration factor to 1 15 for snow and turn snow loading off completely. Included are a series of representative roof truss span tables that will give you an idea of the truss spans available for a particular load condition load duration lumber type and truss configuration.

That means you could lay a 2 x 4 ft. If the bottom chord of a roof truss functions as a floor joist such as in an attic room it carries a live load that also varies by use but a typical live floor load for a residential space is about 40 pounds per square foot. The horizontal bottom chords of most garage trusses are designed to carry the weight of drywall and insulation. The explanations below will help you determine the appropriate truss to use for your application or conditions based on allowable load ratings.

Bcll 0 psf. Bcll 0 psf no storage available in floor trusses. So if your ceiling is unfinished you have some excess carrying capacity up there. If the number of members is labeled m and the number of nodes is labeled n this can be written as m 3 2 n.

Safe load per table 4 1 specifies a 2000 lb over a 2 5ft x 2 5ft area. Load rating chart ct290 load data ct290 truss sections are manufactured using 50mm 1 97 diameter x 2mm 08 wall main tube and 20mm 79 x 2mm 08 wall diagonal tube 6082 t6 aluminum alloy. Both sides of the equation should be equal in order to end up with a stable and secure roof structure. Or the 25 psf snow load could be entered as a roof snow load with the unbalanced snow loading option turned off.

For trusses at 2 ft o c. Is a safe estimate. The formula for truss loads states that the number of truss members plus three must equal the twice the number of nodes. Scrap of plywood over the chords and set about 40 lbs.

This truss load table guide illustrates how to read allowable load ratings for aluminum and steel truss. The live loads a truss is required to bear are determined by local building codes. Total load psf duration factor. The truss is analyzed for each possible location of the 640 plf load along the span.

The box truss is 290mm x 290mm 11 42 x 11 42 square. The shapes and spans shown here represent only a fraction of the millions of designs produced by alpine engineers.