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FAQs

Fire-rated assemblies

Frequently asked questions

National Gypsum Construction Services team answers common questions about fire-rated assemblies

How do I achieve a fire rating if I can only access one side of the wall?

Use UL design W419 for 1-4 hour shaftwall systems or UL design V497 for 1- 2-hour options using multiple layers of gypsum board on one side of minimum 3-5/8” steel studs.

What modifications can be made to fire-rated wall assemblies without affecting the assigned fire rating?

  • Stud spacings are maximums. UL designs with studs spaced 24” o.c. can be used for walls 16” o.c.
  • Stud dimensions are minimums. 6” studs can be used in UL designs that list 3-5/8” studs.
  • Wood structural panels can be added to one side or both sides of fire-rated walls as either the base layer or the face layer.
  • Additional layers of gypsum board may be applied to any UL design.
  • Glass fiber or mineral wool insulation may be added to any UL wall assembly.

In multi-layer assemblies, do I have to fire-tape the base layer?

No, the base layer in multi-layer fire-rated assemblies do not require joint treatment.

How can I upgrade an existing 1-hour, steel stud partition to 2 hours with access from one side only?

UL design V449 is rated for 2 hours from both sides with one layer of 5/8" Gold Bond® Fire-Shield® Gypsum Board on one side and three layers on the opposite side.