Understanding Roof Truss Reaction Bearing Size

Factors that affect truss pricing and cost.

Understanding roof truss reaction bearing size. 7 21 20 20 the first thing to consider with bearing sizes is the minimum required by the building codes. So it is important to specify the actual bearing sizes for the truss. Just remember the acronym. Scissor truss slope differentials between top and bottom chords must be greater than or equal to 2 12 maximum span to depth ratio is 24 for parallel chord roof trusses for example a 24.

Ridge line formed by truss apexes. Roof floor truss manual 7 31 08 10 43 am page 11. Reaction the total load transferred from the uniform load psf applied to the floor truss deck then into the floor truss and ultimately to the floor truss bearing or support. Rim joistan exterior transition member supporting the decking edge and wall sheathing usually tying the ends of floor trusses together.

Intermediate bearing floor truss supported by steel or wood beam special engineering required. R802 6 when a ceiling joist is supported directly on wood or metal the minimum bearing size required. Per 2018 irc international residential code for one and two family dwellings sec. Cojinetes de truss ubicaciones de cojinetes de soporte anchos requeridos de los cojinetes nota.

The important point to keep in mind when you use your truss calculator is that every truss calculation is completely unique and is based on the size of your roof and its specific dimensions. Truss to truss connection details i e hangers maximum reaction force and direction b. Evstudio november 16 2018 building. The truss is a framework consisting of rafters posts and struts which supports your roof.

The span in short is the length of the bottom of the truss. When the minimum required bearing size exceeds the input bearing size the warning required bearing size at joint s greater than input bearing size in the general note section of the truss design drawing is displayed. Understanding bearing size at a wall or beam. The truss chord member bearing on the support.

28 mitek plate allowables psi estimated truss weight fabrication tolerance 29 lumber requirements 30 required bracing for all members 31 reaction pounds bearing size input and minimum required if shown 32 maximum uplift and or maximum horizontal reaction if applicable and maximum gravity if shown. So for example a dimension string that reads. This is the distance of the bottom chord of the truss from outside overhang of bearing wall to outside of the other bearing wall. Roof trusses do not break truss triangulation by removing webs.

In some cases the size or shape of wood trusses is such that some field assembly is required. 4 7 12 would be the dimension 4 7 12 16 or 4 7 3 4. The answer is a convention of the truss producing industry. Maximum span truss with un triangulated heels 20 0.