Roof Truss Bottom Chord Live Load

In other words the truss design drawing should tell you what the truss was designed for.

Roof truss bottom chord live load.

And wind loads per chapter 16 of this code. If the number next to bcdl bottom chord dead load is less than five psf pounds per square foot then the trusses and the building are not designed to support a ceiling. The live loads a truss is required to bear are determined by local building codes. Live loads on roof trusses.

Load bearing walla wall specifically designed to transfer a roof load and or upper floor load into the foundation. 20 4 10 means that the truss was designed for 20 psf top chord live load tcll 4 psf top chord dead load tcdl 0 psf bottom chord live load bcll and 10 psf bottom chord dead load bcdl. The area of the attic where. Truss capacity is listed by pounds per square foot based on the following load rating criteria.

I for sloping or flat roof with slopes up to and including 10 degrees. 2319 17 2 1 3 roof trusses shall be designed for a minimum live load of 30 psf 1436 pa a minimum dead load of 15 psf 718 pa on the top chord and a minimum dead load of 10 psf 479 pa on the bottom chord. 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. Truss bottom chords shall be designed for a uniformly distributed concurrent live load of not less than 10 lb ft2 note that in footnote b the uninhabitable attics without storage have a 10 psf non concurrent live load while this same load in footnote g i e.

In some cases a live load can be applied to a bottom chord either for storage purposes or if there will be movement within the truss such is the case in an attic truss. A when access is provided 1500 n m 2 b when access is not provided 750 n m 2 except for maintenance ii sloping roof with slope greater than 10 degrees. Top chord live load snow and other temporary loads top chord dead load roofing materials weight of the truss itself other permanent items attached to the roof bottom chord live load storage and bottom chord dead load insulation ceiling. Typically roof live load is snow while floor live loads are furniture human occupancy storage.

Machine stress rated lumber msr lumber which has been individually tested. On the truss drawing will be a section which outlines all of the live and dead loads which the trusses are designed to support. The live load shall be taken as follows.