Jim Mitchell

by Jim Mitchell

Principal, Executive Vice President, Director - Civic/Community Studio

Code Corner: Watch Out for Penetrations in a Rated Stair Enclosure!

  • APRIL 06, 2011
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Often, we construct gypsum fire resistance rated barrier enclosure walls around a stair to provide a 1 or 2 hour rating.  The outside membrane of the stair enclosure sometimes then serves as a finished wall for the spaces that surround the stair enclosure, and since they are gypsum partitions, it is often desired to locate penetrations in outer membrane gypsum walls to serve the adjacent spaces.

However, beware that Section 1019.1.2, of the Ohio Building Code (OBC) stipulates that “penetrations into and openings through an exit enclosure are prohibited…” which would include all membrane penetrations, as well as through penetrations, into any fire-resistance-rated assembly, or portion thereof, of the enclosure.

There are a list of exceptions included in Section 1019.1.2, but they are very specific, and do not include a provision for penetrations in outer membrane gypsum outside of the exit enclosure. There is a formal code interpretation which supports this position, so it would be hard to argue this if the condition comes up.

How can this be addressed?  Obviously, the first choice is not to locate penetrations in outer membrane gypsum walls of a fire rated assembly, such as electrical boxes. If an electrical outlet needs to occur at these locations, a furred out wall with gypsum could be provided for the electrical boxes which would be supplemental to the fire rated wall assembly. Or surface mounted boxes and conduit could be utilized, but this condition is rarely found visually acceptable.

The best solution is to pre-plan for this condition and address it in the drawings.  I do know from working with various communities in code enforcement that Chief Building Officials and Inspectors are beginning to look for this infraction, to which repairs/compliance could be costly.

Jim Mitchell

by Jim Mitchell

Principal, Executive Vice President, Director - Civic/Community Studio

Jim has been with M+A since 1981 and currently serves as the executive vice president of the company. Jim's favorite place to eat is Polaris Grille, and his favorite movie is Animal House.