Attic Truss Load Rating

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

Attic truss load rating.

Both sides of the equation should be equal in order to end up with a stable and secure roof structure. The horizontal bottom chords of most garage trusses are designed to carry the weight of drywall and insulation. Of stuff on it. Safe load per table 4 1 specifies a 2000 lb over a 2 5ft x 2 5ft area.

Bcll 0 psf. Alpine truss designs are engineered to meet specific span configuration and load conditions. 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. The truss is analyzed for each possible location of the 640 plf load along 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. Live load psf roof type. The box truss is 290mm x 290mm 11 42 x 11 42 square. For trusses at 2 ft o c.

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. This translates into a uniform load of 640 plf across 2 5 ft of the span. So if your ceiling is unfinished you have some excess carrying capacity up there. Total load psf duration factor.

The shapes and spans shown here represent only a fraction of the millions of designs produced by alpine engineers. 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. Or the 25 psf snow load could be entered as a roof snow load with the unbalanced snow loading option turned off. 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 no storage available in floor trusses. That means you could lay a 2 x 4 ft. Scrap of plywood over the chords and set about 40 lbs. The formula for truss loads states that the number of truss members plus three must equal the twice the number of nodes.

Is a safe estimate. This truss load table guide illustrates how to read allowable load ratings for aluminum and steel truss.