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
Thanks again for your help.