Is the Truss Designer or the Building Designer responsible to calculate snow drift loads on a roof system?
It is the Building Designer’s responsibility to supply snow drift loading information. WTCA’s Standard Design Responsibilities in the Design Process WTCA 1-1995, outlines what is expected from the five parties involved in the design process – building owner, building designer, contractor, truss manufacturer and truss designer. For example, Section 3.2.5 states that one of the building designer’s responsibilities is to provide “The location, direction and magnitude of all dead and live loads attributable to: roof, floor, partition, mechanical, fire sprinkler, attic, storage, wind, snow drift and seismic.” At this point, WTCA 1-1995 is completely voluntary and is not enforced by any agency or building code. By the end of the year [2001], however, TPI should have a new standard in place called ANSI/WTCA/TPI 4-2001 that is based on WTCA 1-1995. The fact that it will become an ANSI document does not make it enforceable but it gives the document more credibility and clout for having passed t
