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Cavity Shaft Wall System

Provide the strength to withstand lateral loads and fire protection necessary for walls that enclose elevator shafts, stairwells and other vertical shafts.

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Find all the necessary components to build strong, fire-protected stairwells and mechanical and elevator shafts.

The Cavity Shaft Wall System includes components that provide the strength to withstand lateral loads and fire protection necessary for walls that enclose elevator shafts, stairwells and other vertical shafts. The system includes gypsum liner panels, gypsum panels and cement board, interior finishing products and framing components.

Main Features

Below are links to products that help detail, specify, bid and install the USG Cavity Shaft Wall System.

Gypsum Liner Panels Gypsum Panels, Gypsum-Fiber Panels and Cement Board Interior Finishing Products Framing Components

Documents & Files

Catalogs & Brochures

System Catalog (English)

SDS, Certifications & Reports

Evaluation Reports (English) PDF 1.3 MB

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q & a

  • How do I install the USG Cavity Shaft Wall?

    The wall should be installed from floor to floor.

  • Where can USG Cavity Shaft Wall be used?

    USG Cavity Shaft Wall can be used in elevator and mechanical shafts, air ducts, stairwells, and areas where wall construction is only available from one side. In addition, USG Cavity Shaft Wall can be used to provide horizontal protection for corridor ceilings, underside of stairwells, and other applications.

  • Is the Horizontal Shaft Wall UL tested?

    While not tested by UL, the system has been tested for fire and is covered for use throughout the United States. The fire test number is WHI 495-PSH-0154/0167 and report number is AER-09038 available at

  • Does USG offer a three hour rating for the Cavity Shaft Wall?

    Yes, U416.

  • What structural header is required above a two-hour fire damper located within a two-hour fire rated USG Cavity Shaft Wall system?

    The design of structural members containing fire damper assemblies is normally the responsibility of the fire damper manufacturer, and not USG. This is for proper operation of the fire damper during a fire.

  • I need to have a 2 hr. rated corridor ceiling. What can you offer?

    USG Cavity Shaft Wall

  • Can studs be substituted in UL design test number?

    Yes. It is possible to substitute studs as long as the stud is of thicker gauge, size, or both.

  • How are the Double USG E-studs attached?

    Fasteners should be located at both ends, and staggered 12 inches or closer the full length of the studs.

  • Can the Horizontal Shaft Wall be penetrated for light fixtures?


  • What type of fire rating can I get with a USG Cavity Shaft Wall?

    USG Cavity Shaft Walls provide UL tested 1- to 4-hour fire resistance.

  • What sizes are available for USG C-H Stud?

    2 1/2", 4" and 6" 25, 22 and 20 gauge. Please contact your local USG Representative for pricing and availability.

  • Can the Horizontal Shaft Wall carry live loads?

    No. The ceiling is designed to carry only its own weight.

  • How can a fire rating be achieved with access to only one side of a partition?

    A shaft wall can be built in front of the existing partition. This system can be used for ratings of up to 4 hours.

  • In the literature piece SA926, I see limiting height tables for unlined shafts, as well as regular shafts. What is the difference?

    The difference is in one case the load is considered intermittent, or the load is only applied as the elevator moves by. In the other case the load is sustained or constant. This would be the case for air handling systems. The sustained load is far more severe. The codes allow us to increase the allowable stress by 1/3 if the load is considered intermittent.

  • Who makes the steel components for USG Cavity Shaft Wall?

    All steel framing components for USG Cavity Shaft Wall are made to precise USG Specifications.

    Depending on the market you are in, the product will be made at one of three manufacturing locations:

       • Marino/Ware Industries, South Plainfield, NJ
       • USG Medina, Medina, OH
       • CEMCO, City of Industry, CA

  • What are the UL Design numbers for USG Cavity Shaft Wall?

    UL Design Numbers U415, U438, U459, U467, U469, and U492.

  • Can the Shaft Wall span be greater than what is published?

    In order to achieve span heights greater than the limited spans the system must be tied back to the structure. The Architect or Engineer of Record determines the details for this attachment.

  • Can you test a wall assembly horizontally to acquire a fire rating for a ceiling?

    Not in general. The exception is the Sheetrock® Brand Shaft Wall, which is the only wall assembly that can be tested for ceilings by testing it horizontally.

  • My project design requires that a continuous run of USG Cavity Shaft Wall be installed beyond the limiting height allowance listed in the SA926 brochure. What can I do to solve the problem?

    For heights exceeding the limiting height tables found in the System Catalog (SA926) brochure, we recommend installing the 20 gauge x 6" C-H Stud in combination with a standard 4" C-Stud of heavier gauge. The two stud sections should be fastened together (back-to-back with fasteners spaced 12" o.c. and staggered. The design or project structural engineer must review any design.

  • Can you use the USG Cavity Shaft Wall in a curved condition?

    The system does not lend itself for tight radii. A 50 radius has been done, but anything less would require the assistance of the USG Architectural Services group. They can be contacted at 1-800-USG-4YOU (800-874-4968).  

  • Is it possible to substitute Type C for Type X?

    Yes. Type C can be used in place of Type X, but Type X cannot be used in place of Type C.

  • What are the components of USG Cavity Shaft Wall?

    Sheetrock® Brand Gypsum Liner Panels & Sheetrock® Brand Gypsum Panels (Firecode, Firecode C, or Ultracode Core. Please refer to the appropriate fire-resistance design for specific panel selection.

  • In the Sheetrock® Brand Shaft Wall System, can 5/8 inch Type X gypsum board be substituted for 1/2 inch Type C gypsum board?


  • Is the Thermafiber insulation necessary? Can I substitute fiberglass insulation?

    There are designs that require Thermafiber insulation to achieve the fire rating. Check the UL Fire Resistance Directory for the specific design requirements. In other assemblies, the Thermafiber insulation is used to increase the STC. Fiberglass insulation cannot be substituted for Thermafiber insulation.

  • Where can Double E-studs be placed?

    Do not locate the splice in the middle 1/3 of the span.

  • How is the air pressure load determined? If I am not using the USG Cavity Shaft Wall in an elevator shaft, can I work off of the 5 psf pressure load?

    The elevator cab speed and the number of elevators per shaft determine the air pressure load. Yes, if not enclosed in an elevator shaft you can work off the 5 psf pressure load.

  • Is it necessary to tape the joints of the 1-inch Sheetrock® Brand Gypsum Liner Panel in a USG Cavity Shaft Wall assembly?

    No. The joints do not require tape, however it is necessary to stagger the joints of the liner panels. Please refer to System Folder System Catalog (SA926) for detailed information on this application.

  • I have an air duct I need to enclose. Can I use USG Cavity Shaft Wall?

    Yes. USG has a design for a 2-hour Cavity Shaft Wall enclosure.

  • How do I treat the horizontal butt joints of the 1-inch Sheetrock® Brand Gypsum Liner Panels in a USG Cavity Shaft Wall?

    The Fire Resistance Rating does not require any joint finishing of the horizontal butt joints of the 1" Liner Panels. We do recommend for heights greater than 12 feet the horizontal butt joints be staggered for proper structural integrity of the wall system. Please refer to USG Cavity Shaft Wall System Catalog (SA926) for additional information.

  • Can Double E-studs be spliced?

    Yes. We recommend that the splice not be located in the middle 1/3 of the span.

    Please refer to System Catalog (SA926) for additional information.

  • In the literature piece SA926 in the base section detail there is a piece of gypsum board at a 75 minimum angle. What is this for and is it required?

    When the slab extends over 2" from the interior side of the Shaft Wall that piece is there to offer protection from things falling onto the ledge and to provide safety to ensure nothing can sit or be left there. It does not have an effect on the fire rating.

  • Can I substitute other products in these USG Cavity Shaft Wall assemblies?

    No. Only the products indicated in the UL Design should be used to construct the USG Cavity Shaft Wall.

  • Can USG Cavity Shaft Wall be used for vent shafts?

    Yes. USG Cavity Shaft Wall vertical vent shaft assembly rated 2 hours per UL Design Number U529.

  • What is the limiting height of the USG Cavity Shaft Wall?

    The limiting height is based upon the stud size and gauge, allowable deflection and air pressure load. System Catalog (SA926) contains a limiting heights chart.

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    Call our Technical Support team at 800-874-4968 (Monday-Friday, 7:30 am - 4 pm Central).