Thread: Surface Rusting Structural Steel

Is there an issue that would need to be reported with surface rusting of open web bar joists and steel roof deck?

The building has been vacant for a while and had some prior roof leakage issues. Overall, the rusting does not appear to have progressed to the point of a structural integrity issue.

I wasn't sure if reconditioning should be recommended or not.

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Jon,
In my experience, steel stock often has surface rust when it is delivered from the supplier. In a first class installation it would be cleaned and primer applied. In most cases this is not done and has no practical adverse affect.

If I was convinced the surface rust formed after the installation, I would tend to focus on identifying the building conditions that are conducive to causing rust such as the roof leaks you mentioned, AC not removing humidity, etc.

Darrel Hood
DILIGENT PROPERTY SERVICES

Jon, Since the roof has some leakage concerns I'd defer the decking to the roofing contractor and let him run with it. The rusting is a reasonable condition to point out and had there not been a need for a repair for leakage I'd write that the rusting (that you referenced) should be monitored.

Jon

Surface rust is of no structural problem, its rust that goes deep enough to significantly reduce the cross sectional area of the steel members that creates a problem. Then it will depend on which member, top , bottom or web and its location within the span. Web joists like other beams are design based upon the bending, shear and deflection requirements of the job. Those forces change depending upon the location along the joist or beam. To complicate matters the load can vary between beams. Designers typically, for ease of construction, will design the beam for the work case and specify that size for all. So what might not be a problem for one beam may be significant for another identical beam in another location.