Roof Truss Load Path

The sheathing transfers the loads to the roof rafters.

Roof truss load path.

All roof and wall loads are assumed to be uniform with no concentrated loads on the trusses or walls present. Vertical load path in traditional sloped roof framing loads are transmitted vertically downward through the roof framing to the exterior walls that transmit the load downward to the home s. The building is designed for design load possibilities that may never occur. If one part of the load path fails or is discontinuous building failure may occur.

This allows wind uplift forces on the roof to be safely distributed through the walls to the foundation. 50 psf x 14ft 700 pounds per lineal foot. A primary goal for buildings subjected to high winds is to maintain a continuous load path from the roof to the foundation. I for sloping or flat roof with slopes up to and including 10 degrees.

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. Live loads on roof trusses. Load path loads on the roof are initially supported by the sheathing. To transfer loads from the wall above to the truss ends where they can be transferred to the wall below.

The truss could be designed based on the assumption that the 25 psf roof snow load is a factored ground snow load in which case a ground snow load is back calculated using asce 7 based on the specified roof snow load pg 25 psf therein lies the problem with specifying only a roof snow load. Design loads the building dead load is the only known load. Roof truss span tables alpine engineered products 15. Total load psf duration factor live load psf roof type 55 1 15 40 snow shingle 55 1 15 30 snow tile 47 30 snow 40 20 snow 1 25 20 construction or rain not snow load 55 1 15 40 snow 47 1 15 30 snow 40 1 15 20 snow 40 1 25 20 rain or constn.

All other forces will vary in magnitude duration and location. The live load shall be taken as follows. Truss spanning between bearing walls. R roof live load w wind load s snow load e earthquake load r rain load.

The roof rafters transfer the loads to the ceiling joists and to the bearing walls that support the trusses. The irc does not provide specific guidance as to when blocking may be required to transfer the loads directly. 910 pounds per lineal foot.