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Re: Roof Framing, Joist Spacing...Input please

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Scott,

  <<  I will say again that I am not sure where you are getting the 5'-0"
limit.>>

I refer to SDI Specifications and Commentary ie: "Recommended Maximum Spans
for Construction and Maintenance Loads Standard for 1 1/2" and 3 Inch Roof
Deck."

In these tables, note that NR22 with a span condition of "2 or more" is SDI
limited to a max span of 4'-9".  In the corresponding load tables of
Vulcraft's same catalog under "VERTICAL LOADS FOR TYPE 1.5F", again, lists
"Max. SDI Const. Span" as 4'-9", yet the Vulcraft load tables allow a 41 PSF
load for a single span on this same deck on a span condition of 6'-0".  I
consider a 41 PSF a reasonable load combination in this area.

To futher add to the confusion, Vulcraft lists F22 deck on a three span
condition as SDI maxed at 5'-10", (conflicting with SDI published tables of
4'-9" for "2 or more spans")  This same deck in Vulcraft's catalog on a
three span condition is listed as 41 PSF at a 7'-0" span condition.  Again,
a reasonable load combination in this area.

I am looking at Vulcraft's 1996 catalog on p.4 with the SDI "Max Spans"
listed on p. 10.  It is not untill one reaches a deck configuration of NR18
in the SDI tables that the allowable single span exceeds 5'-0".

I certainly don't call these restrictive SDI load limits as "promoting" the
use of steel decks.  About the only thing I see it "promoting" is confusion
and the likelihood of a lawsuit.


Jimmy  C.......(hisself)




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