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By: Robert Grupe
Director, Architectural and Technical Solutions, United States Gypsum Company

Phil Shaeffer
Manager, Codes and Technical Support, United States Gypsum Company

Dean Updegrove
Product Marketing Manager, United States Gypsum Company

	Gypsum shaft walls (seen here from inside the cavity) are the thinnest and lightest-weight shaft walls available.

Gypsum Shaft Walls

Since their introduction nearly 40 years ago, gypsum drywall shaft systems have offered architects a highly attractive combination of performance and installation benefits. As such, they are considered the preferred choice for most applications. The systems are lightweight. A two-hour fire-rated gypsum wall weighs only 9 pounds per square foot. They are thin. A two-hour fire-rated wall is only 31/2 inches thick. They also install more quickly and economically than “wet” shaft walls, such as masonry. Gypsum panel shaft walls are completed early in the construction process and finished later, along with other interior partitions. Most importantly, the systems have undergone extensive independent testing for fire, sound and structural performance.

The most widely used gypsum shaft wall system consists of only five components. They are:

• Gypsum Liner Panels – 1-inch-thick and 24 inches wide, with double-beveled edges
• Gypsum Panels – 5/8-inch-thick Type X or 1/2-inch-thick Type C core
• Steel C-H Stud – 21/2, 4 and 6 inches deep, 25, 22 or 20 gauge
• Steel J-runners – 21/2, 4, and 6 inches deep, 24 or 20 gauge (J-runners may also be used as starter studs.)
• Steel E-stud – 21/2, 4 and 6 inches deep, 25, 22 or 20 gauge

Substitutions for any of these components are not advisable without a thorough evaluation by the architect. Substitution is typically outside the scope of independent system evaluation and therefore is not endorsed by system manufacturers.

Installation of the gypsum shaft system is handled as follows:

1. J-runners are attached to the concrete floor and to the structure above. Attachment is accomplished using a power-driven fastener of a known pull-out and shear capacity.

2. An E-stud is vertically attached along one side of the terminating wall or structural element. In cross-section, the E-stud, in fact, looks like an “E,” and is designed to receive a 1-inch-thick, 2-foot-wide gypsum liner panel.
(J-runners can be used as an alternative to E-studs.)

3. A gypsum liner panel is placed into the top and bottom of the J-runners and fitted into the E-stud. Because no fasteners or adhesives are required, the application moves quickly. (When using J-runners instead of E-studs, attachment screws are required.)

4. A C-H-stud is then placed over the free edge of the liner panel and the next panel is positioned within the J-runners and inserted into the “H” portion of the stud. The C-H-stud provides a tight friction fit along the entire length of the panel to eliminate rattles when in service. Again, no fasteners or adhesives are needed. Like the E-stud, the C-H-stud derives its name from its cross-section profile. The “C” section of the stud forms a cavity that can hold insulation, as well as plumbing and electrical lines. It has 1-inch-diameter holes located 16 inches from each end to accommodate horizontal conduit runs. The “H” portion of the stud features vertical slots to minimize heat transfer through the stud.

5. The installation continues progressively. Each succeeding liner panel is fitted with a C-H-stud and the next liner panel is inserted until the full length of the wall is reached. The wall is completed by fitting the final gypsum liner panel into another E-stud or J-runner attached to the intersecting construction.

6. After the gypsum liner panels are installed, one or more layers of 5/8- or 1/2-inch-thick Type X or Type C core gypsum wallboard panels are screw-attached to the front of the “C” section of the studs. The face panels are finished using standard wallboard joint compound and tape, then primed and painted. For enhanced abuse resistance and a more monolithic look, Type X or Type C veneer plaster base panels finished with veneer plaster can be used in place of the gypsum wallboard.

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