NFPA mezzanine definition

[Inspector Gadget]

A municipality in our region is constructing an aircraft hangar. NFPA 409 is a document being used as a reference in the design.

The proposed design (which I haven't seen) features an open second storey that under Canadian codes cannot be considered a mezzanine. [In National Building Code of Canada - NBCC - , mezzanines are storeys if the area of the mezzanine exceeds 40% of the open area of the floor below AND do not contain enclosures that exceed 10% of the floor area.]

NFPA 409 requires sprinklers for any hangar with more than one storey (Group III does not require sprinklers, group III limited to one storey; Group II requires sprinklers...)

My thinking is this: While I naturally have to use NBCC within my normal plans reviews, I'm of the view that if the design does not meet the trigger of being two storeys *as NFPA intends* that our office wouldn't have to apply the sprinklering requirements of NFPA 409 for a two-storey hangar.

NFPA obviously doesn't use Canadian Code definitions/restrictions for mezzanine area, etc, but NFPA 409 does NOT reference IBC or ICC Codes, either. Looking at what NFPA uses to delineate a mezzanine versus a storey, NFPA 101, one of the documents referenced in NFPA 409, defines a mezzanine as an open area that does not exceed 30% of the open floor area. Enclosed areas appear to be exempt if the occupant load of the enclosed area is less than 10.

Any contrary views?

 

[jar546]

A municipality in our region is constructing an aircraft hangar. NFPA 409 is a document being used as a reference in the design.

The proposed design (which I haven't seen) features an open second storey that under Canadian codes cannot be considered a mezzanine. [In National Building Code of Canada - NBCC - , mezzanines are storeys if the area of the mezzanine exceeds 40% of the open area of the floor below AND do not contain enclosures that exceed 10% of the floor area.]

NFPA 409 requires sprinklers for any hangar with more than one storey (Group III does not require sprinklers, group III limited to one storey; Group II requires sprinklers...)

My thinking is this: While I naturally have to use NBCC within my normal plans reviews, I'm of the view that if the design does not meet the trigger of being two storeys *as NFPA intends* that our office wouldn't have to apply the sprinklering requirements of NFPA 409 for a two-storey hangar.

NFPA obviously doesn't use Canadian Code definitions/restrictions for mezzanine area, etc, but NFPA 409 does NOT reference IBC or ICC Codes, either. Looking at what NFPA uses to delineate a mezzanine versus a storey, NFPA 101, one of the documents referenced in NFPA 409, defines a mezzanine as an open area that does not exceed 30% of the open floor area. Enclosed areas appear to be exempt if the occupant load of the enclosed area is less than 10.

Any contrary views?

NFPA 409 does not define Mezzanine and it is only mentioned 3 times.
11.14.4
In Group IV hangars that require protection in accordance with 11.14.1, 11.14.2, or 11.14.3, all mezzanines used for storage and all enclosed areas including separate shops, offices, and storage areas located in membrane-covered rigid-steel-frame-structure hangars shall be protected by an approved automatic sprinkler system in accordance with NFPA 13.

 

[tmurray]

It would be appropriate to use the intended definition from those drafting the code/standard.

Are they voluntarily getting a permit?

Aviation falls under federal jurisdiction and Transport Canada exercises their right to interjurisdictional immunity over provincial and local building inspection regimes.

Here is a good summary of the leading decision: https://www.lexpert.ca/archive/gtaa-v-city-of-mississauga/348570

It is important to note that interjurisdictional immunity is not related to the ownership (government vs. private) of the land, but constitutional jurisdiction over the use taking place on the land.

The only case I have read where it was not upheld was when someone was clearly trying to use interjurisdictional immunity to skirt around the building inspection regiment. He claimed to be building an aircraft hanger, but did not have a pilots license, own an aircraft, or have a business leasing hanger space to people who do own aircraft.

A builder/owner can voluntarily subject themselves to a building inspection regime despite having interjurisdictional immunity. However, they may choose their level of involvement and would not be subject to enforcement actions.

 

[Inspector Gadget]

It would be appropriate to use the intended definition from those drafting the code/standard.

Are they voluntarily getting a permit?

Voluntary, municipally owned property, post-disaster building due to the intended use.

 

[Yankee Chronicler]

Any contrary views?

What's your question?

NFPA is not the ICC and is not the NBCC. NFPA standards are NFPA standards, and with them the NFPA definitions apply.

You have said this proposed hanger has an upper level that can't be considered a mezzanine under the NBCC. Is that because the NBCC limits mezzanines to 40% of the area of the story in which the mezzanine is located, and this upper level exceeds 40% of the area of the main floor? If so, it's a story -- so you're dealing with a 2-story structure.

The NFPA limit on the area of mezzanines is more restrictive than the NBCC limit, so it's a 2-story building for the NFPA, also.

You need sprinklers.

 

[Inspector Gadget]

The NFPA limit on the area of mezzanines is more restrictive than the NBCC limit, so it's a 2-story building for the NFPA, also.

IIRC - and again, I haven't seen the design - the issue is not the 40% (30%) but that there is an enclosed area that exceeds the 10% threshold under NBCC but may not exceed the 10 occupant load under NFPA.

In any case, it's still in the designer's court. They're aware of the issue, and I'd wager they'll find some solution - I'd just move services to a first-storey structure.