What should I do if a shaftwall needs to be higher than the limiting heights table will allow?
The limiting height can be increased by switching to thicker steel (lower gauge), using a deeper stud, lowering the deflection criteria, lowering the operating pressure, or adding an extra board layer. Example: For the same deflection criteria, operating pressure and stud depth, you can increase the limiting height from 14’2″ to 15’10” by switching from 25 to 20 gauge steel for the 1-hour design. For a 2-hour design, use two layers of board and the corresponding limiting height goes up from 14’2″ to 15’6″. The operating pressure is the pressure exerted on the shaftliner surface by air when the elevator travels up and down. At some point, you will exceed the maximum limiting height, for instance, if you want to build a 45′ high wall. This number obviously is higher than the highest number given in the table. In such cases, three or four shaftwalls making up the 45′ height should be built on top of each other using a back-to-back J track arrangement. Each wall needs to be supported by a
