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RE: Roof Deck Personnel loading

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Roger,

You are Correct for uniform loading.  My question is how we tell an
owner it is safe to walk on the roof.

Scenario 1:   An employee weighs 200 pounds and can easily stand with in
the 12" square tile on the office floor.  This computes as 200 psf.  The
owner asks "It is safe to walk on a 30 psf roof????"

Scenario 2:  The metal roof deck spans 4 ' between the joists.  A - 200
pound man are standing on a bay 12" wide between the joists.  Another
200 pound man walks up and stands beside him to look at the AC unit.
Their weight on the deck bay is now 400/1/4 = 100 psf.  The combinations
are endless.

I have not seen any information in SDI that can document that the
loading is safe.



Ronald A. Hill, P.E.
HILL Consulting Engineering
PO BOX 26525
Birmingham, Alabama 35260 USA
Phone: 205-823-4784
FAX: 205-823-4145
email: ronhill(--nospam--at)hillce.com
http:\\www.hillce.com


-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com] 
Sent: Friday, September 20, 2002 10:29 AM
To: seaint(--nospam--at)seaint.org
Subject: Roof Deck Personnel loading

Ron,

I think that the 30 psf roof load relates more to stacking roofing
materials 
and the effect of snow than it does to personnel loading.

For personnel to come close to the 30 psf loading, you would have to
have 180 
pound people standing 2.5 feet apart over the entire considered area.
In 
other words, it would be quite congested.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Ron Hill wrote:

. > I have a question about roof decks and 30 psf live loading.  I have
. > looked in the codes and in the manufacturers data concerning
permissible
. > personnel loading on roof decks and can not find anything. 

. > When we design a roof for a uniform live load of 30 psf, how does
that
. > correlate to how many men can stand in one area on the roof at any
given
. > time??

. > Ronald A. Hill, P.E.

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