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OFS — Firestop Spacers

How to Specify

Using tables from the National Fuel Gas Code or our Sizing & Application Guide, determine the diameter of venting required. The Sizing & Application Guide also offers tips on good design including multi-appliance system sizing and design.

How to Purchase

Vent FAQs

OFS — Firestop Spacers


  • The firestop spacers center vent in 16" O.C. stud space and serve as a firestop at the ceiling level. This is a required component for Type B 2 x 4 and multi-story Type BW installations.

Firestop Spacer dimensions (inches)

4OFS4"2" x 4"
5OFS5"2" x 4"
4OFS64"2" x 6"