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RE: Wind load-gable vs hip roof

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I'm in digest mode, sorry about the delay.
 
I don't see where Figure 6-2 refers to hip roofs at all, although I suppose Method 1 could apply to hip roofs since Method 2 now also appears to apply to hip roofs in the 02 edition. Also, zone C does not necessarily refer to the gable end of the wall...just the wall perpendicular to the MWFRS direction being evaluated (not neccessarily the same as wind direction). The 8.5 psf you refer to applies to a building with a flat roof since theta is measured from horizontal.
You would need to use Figure 6-3. As far as the actual wind pressures, you should see a rise in pressure on the wall zone 'C' as the roof pitch increases since more of the wind is "stalled" and more force is transferred to the wall as required by Bernoulli's principle. At least this is my understanding. 
 
 
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From: "Chies, Bill NAB02" <Bill.Chies(--nospam--at)nab02.usace.army.mil>
To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
Subject: Wind load-gable vs hip roof

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Is the wind load less for the walls of a gable roof or a hip roof. Figure
6-2 of ASCE 7-02 shows that the horizontal wind pressure (zone C) on the
vertical walls (below the roof line) is 8.5 psf for the gable end and 11.5
psf for a hip roof with a roof angle of 35 to 45 degrees. Looks like this is
saying a hip roof actually increases the wind load on the vertical wall
below the roof bearing (more than a gabled roof). Why is this? TIA   Bill

Christopher A. Banbury, PE
Vice President
Nicholson Engineering Associates, Inc.
PO Box 12230, Brooksville, FL 34603
7468 Horse Lake RD, Brooksville, FL 34601
(352) 799-0170 (o)         (352) 754-9167 (f)
www.nicholson-engineering.com