Engineered Framing

COMMON FRAMING PROBLEMS AND HOW TO AVOID THEM

Transferring Roof Loads In today's large houses, the complexity of some roof structures makes it difficult to properly support some of the members.Too often, hips and valleys are unsupported or tied into lower ridges that are also unsupported.Hip and valley rafters need to be supported by headers ordoubled-up rafters to handle the loads. Headers aroundopenings such as skylights, up to 4 feet long, can be put insquare with the rafters. Headers over 4 feet should be put inplumb and its members stepped to follow the slope of the roof. Header rafters more than 6 feet long should be supported by framing anchors.   Roof loads are also transferred by the use of purlins and struts that will reduce long rafter spans. Specific requirements for the size and span of purlins, and the size and maximum unbraced length of struts can be found in the conventional construction provisions of the building code.  

Figure 1  : Transfer roof loads using purlins and struts. Transfering roof loads1