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RE: Factory Mutual Span

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The FMRC Approval Guide has a listing titled, "Steel Roof Decks Class 1 Fire
& I-60 or I-90  Windstorm Rated".  This document gives guidance on maximum
roof deck spans and minimum fastening requirements for steel roof decks that
are insured and rated through Factory Mutual.

If an owner desires a "Factory Mutual" roof, the structural engineer should
review the requirements contained in the FMRC Approval Guide for the
appropriate requirements.  Generally a 6'-0" span is O.K. for most roof deck
manufacturers.  I am aware of only a couple of exceptions.

The big requirement that is occasionally overlooked, is the sidelap fastener
requirement.  All FM steel roof decks require sidelap fasteners unless
supporting steel members are at a spacing less than or equal to 36".
Fastening of steel deck to supporting members is not to exceed 12".

Harold Sprague

> Richard Lewis wrote:
> > I am looking for information on the maximum Factory Mutual span for 22
> ga.
> > 1-1/2" wide rib roof deck.  My United Steel Deck catalog gives a 6'-0"
> max
> > span for the FMS span.  The footnote tells me this is for  class 1
> > construction.  It refers to FMRC Approval Guide.
> >
> > Can anybody elaborate of what this means?
> >
> > __________________________________________________
> >
> > Richard Lewis, P.E.
> > Missionary TECH Team
> > rlewis(--nospam--at)
> >