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Re: 1997 Building drift limits

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Thanks for your response to my question on drift. The clarification in the 
Blue Book Commentary to section 1633.2.4 will help.

I perform design calculations on cladding systems on projects in many cities 
and several states.  Many of these building departments will be adopting the 
1997 UBC and checking my design against the provisions of this code. They 
probably don't have the Blue Book and if they do, won't consider the Blue 
Book to take presidence over the 1997 UBC.

Many of the cladding systems are manufactured systems that were developed at 
great R&D expense to accomodate .005h drift and will not work with what 
appears to be a five-fold increase in building drift.  In the design of the 
building, the architect specifies a specific manufactured system in the 
design and the project is put out to bid based on the use of this specified 
system.  If the system is rejected at plan check because it cannot accomodate 
.025h drift, there will be serious problems that will ripple all the way back 
to the architectural design.

Any suggestons you could give me on how to head off these problems would be 
greatly appreciated.

Thanks again for your help.

Jim Sadler