Steel Trusses and Wood Purlins

by Don Friedman on May 19, 2017

No deep thoughts today, just appreciation for a well-designed roof. It’s an industrial building so finishes were kept to a minimum, and there was no requirement for fire-rating. The trusses are steel because they span about 50 feet; the purlins span 18. The end bays have diagonal rod bracing in the plane of the truss upper chords to allow the roof to serve as a diaphragm for resistance to wind loads.

Given the technology of the era of construction – no plywood, no welding, relatively low ratio of labor-to-material costs for steel – this is just about perfect. I can’t think of any way it could have been built better. With today’s technology we’d design in differently, but not necessarily any better.

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