Fire Rated Lobby When Connected to Corridor?

2/11/2020

We have a dormitory project where, on the first floor, and entry lobby at the front entrance connects directly into a main corridor that runs the length of the dormitory. On either end of the corridor are exterior exits. There are also exit enclosures from the two upper levels that discharge to the exterior on both ends of the building. This project is under NFPA 101-2018 and is fully-sprinklered.

NFPA 101-2018 7.1.3.1 and 28.3.6 state the following:

7.1.3 Separation of Means of Egress.
7.1.3.1 Exit Access Corridors. Corridors used as exit access and serving an area having an occupant load exceeding 30 shall be separated from other parts of the building by walls having not less than a 1-hour fire resistance rating in accordance with Section 8.3, unless otherwise permitted by one of the following:
(1) This requirement shall not apply to existing buildings, provided that the occupancy classification does not change.
(2) This requirement shall not apply where otherwise provided in Chapters 11 through 43.

Because this is a new dormitory, Chapter 28 also applies:
28.3.6 Corridors.
28.3.6.1 Walls.
28.3.6.1.1 Exit access corridor walls shall comply with 28.3.6.1.2 or 28.3.6.1.3.
28.3.6.1.2 In buildings not complying with 28.3.6.1.3, exit access corridor walls shall consist of fire barriers in accordance
with Section 8.3 that have not less than a 1-hour fire resistance rating.
28.3.6.1.3 In buildings protected throughout by an approved, supervised automatic sprinkler system in accordance with
28.3.5, corridor walls shall have a minimum 1∕2-hour fire resistance rating.

Our question is - is the lobby, by code, considered part of the corridor (and therefore need to be rated)?

Two ways of looking at this - one is that the code is strictly only discussing requirements for the corridor and not a lobby. The other way of looking at it is that the lobby is acting as the corridor when it serves as part of the exit access for the building.

Normally a 1/2-hour rating wouldn't make all that much of a difference, but there's storefront in the lobby space between an adjacent office and the lobby which would have a cost impact to the project.

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Michael Major

2/11/2020 01:10:54 pm

I hope this helps.

7.5.1.2 - Corridors shall provide exit access without passing through any intervening rooms other than corridors, lobbies, and other spaces permitted to be open to the corridor, unless otherwise provided in 7.5.1.2.1 and 7.5.1.2.2.

7.5.1.6 - Exit access from rooms or spaces shall be permitted to be through adjoining or intervening rooms or areas, provided that such rooms or areas are accessory to the area served. Foyers, lobbies, and reception rooms constructed as required for corridors shall not be construed as intervening rooms. Exit access shall be arranged so that it is not necessary to pass through any area identified under Protection from Hazards in Chapters 11 through 43

Kelly

2/12/2020 09:54:01 am

Love how these LS questions are always super quiet on here...I feel like the crowd on this site is def skewed suppression.

I don't have access to my codes at the moment, so I cannot really do a thorough analysis of your situation, just FYI. But I like to think of these kinds of problems from a first principles basis. The idea behind requiring separation from corridors is that the occupants, in a worst case scenario in these types of buildings, can possibly shelter in place and be rescued from the window (ie why there needs to be an emergency egress, why there are so many additional requirements for windowless buildings and buildings below grade, etc). If there is a dorm room bordering both the lobby and the corridor, wouldn't the required separation be compromised?

IF according to your code analysis, a separation between the dorm rooms and lobby is not required, then why wouldn't you simply put a rated door on the corridor to separate it from the lobby rather than rating the whole lobby? I would think that'd be a more cost effective solution, and one that serves to protect the corridor (egress access) from a fire that is in the lobby or on the other half of the building.

In my opinion, without looking into the codes, I would think you'd need to rate the first floor lobby 1/2 hour. I would also look more closely at your storefront separation requirements - might be dictated by IBC rather than 101 depending on the jurisdiction.

James

2/13/2020 11:53:50 am

Very well said Kelly! Agreed entirely, especially on the "big picture" view on an overall code approach.

Fire Rated Lobby When Connected to Corridor?

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