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What You Should Know About Cavity Shaftwalls

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Nov 1, 2019 by Thad Goodman

OnBoard Newsletter | November 2019

OnBoard November 2019 | Cavity Shaftwall System

Do you know everything you need to know about cavity shaftwall systems? We receive many inquiries about them.

Used in commercial construction, cavity shaftwall systems are non-load-bearing, 1-hour to 4-hour, fire-rated partitions constructed from one side and used to enclose elevator shafts, stairs and mechanical shafts where the design requires resistance to both fire and air pressure. These systems can also be used as fire-rated, interior partitions where access is restricted to one side and as fire-rated, horizontal membranes.

Since many of you will be specifying cavity shaftwall systems for upcoming projects, we thought it would be helpful to share some of our most frequently asked questions and answers.

Answers to the Most-Asked Questions About Cavity Shaftwalls

Is it permitted to stack 1” shaftliner panels in a cavity shaft system?

When is a hardened shaft required and how do we achieve and specify a hardened shaft?

How are cavity shaftwall corners constructed?

Can horizontal shaftwall assemblies be used for a rated corridor ceiling?

Can cavity shaft systems be used for fire-rated mechanical and vent shafts in wood-framed buildings?

Are shaftwall stud types interchangeable between UL-rated designs?

How can I achieve a higher STC shaft assembly?

Can the shaft assembly overhang the slab edge – and if so, how much?

What is the recommended patching method for cavity shaftwall systems?

What are the suggested elevator door framing and guide rail details in cavity shaftwall assemblies?

Am I required to tape face panel joints in a fire-rated shaft assembly?

More Questions About Cavity Shaftwall Systems?
Call or email your Construction Design Managerfor more information. Also, if you have additional questions about products to incorporate, don’t hesitate to reach out. We’re here to help you design and build better.

National Gypsum’s UL Cavity Shaftwall Systems (1-4 hour)

1-hour Rated Shaft Assemblies
U499
W419 (System A)

2-hour Rated Shaft Assemblies
U428
U497
W419 (System B and System D)
W441

2-hour Rated Stair Shaft Assemblies
U429
U498
W419 (System C)

3-hour Rated Shaft Assemblies
W414
W419 (System E)

4-hour Rated Shaft Assemblies
V451
W419 (System F)

"Shaftwall and area separation wall gypsum product assemblies are options for many building types. Concrete Masonry Units (CMUs) and concrete walls have been and will always be excellent choices for fire protection. Gypsum has carved out a place in the built environment with its unique fire resistance. Knowing where and when to use both of these options can save money and time on construction projects. Call our tech line (1-800-NATIONAL) early and often for support."

Thad Goodman

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Thad Goodman

Construction Design ManagerNational Gypsum

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