Concerns/Issues in Protecting All-Glass Atrium?

10/26/2022

Looking for some insight on a project I'm reviewing.

We have an 1,800,000 sqft storage occupancy with business and assembly mixed in. It has a 2-story open foyer main entrance. The graphic annunciator and fire alarm panel are in the same location.

My problem is the 2-story space is all glass around the means of egress.

How would sprinkler protection and using the the graphic annunciator work in a all-glass space?

I'm looking to get sprinkler coverage at the glass window, which are floor-to-ceiling. Also, the outside wall in the corner of the building is all glass too.

Looking for insight on how to approach this and any concerns you might have regarding an all-glass space.

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

5 Comments

matt

10/26/2022 08:06:59 am

are the walls required to be fire rated as part of the egress corridor? If they are required to be rated, then you can use window specialty sprinklers to achieve a 2hr rating. the sprinklers have very specific requirements for the window construction though - so keep an eye on that.

sean

11/8/2022 10:58:17 am

unless some very specific requirement came in there is an exception for two story atrium not requiring any special features.

Alex

10/26/2022 08:27:55 am

Hi,

I would first check with Table 705.5 (IBC 2021 edition) to verify your fire-resistance rating requirements for non bearing exterior walls. Assuming your fire separation distance is greater than 30 feet, your exterior wall does not require a fire rating.

Although, if you are less than 30 feet, and do not meet the fire separation distance and the construction type for 10 to 30 feet, your wall will require a (1) hour rating. If this is the case, I believe using fire rated glass is your best bet. Again, nothing changes for your sprinkler system.

I'm not sure of your question regarding the graphic annunciator. I would install it adjacent to the panel, on a non glass wall.

Thanks,
Alex

Todd E Wyatt

10/26/2022 09:15:47 am

The first step is to determine IF the scoping Code (e.g. 2021 IBC) requires an automatic sprinkler system (ASPS) for the (3-4) Occupancy Classifications (OC) identified :

A) Group S-1 Moderate-hazard Storage
B) Group B Business
C) Group A-2 Assembly (e.g. Cafeterias)
D) Group A-3 Assembly (e.g. Conference Rooms)

Per 2021 IBC 903 Automatic Sprinkler Systems, these are the requirements for an ASPS by OC :

A) Group S-1 Moderate-hazard Storage
ASPS required IF the Fire Area (FA) >12000 SF or if the FA is >3 stories above grade plan (Not Applicable) or if the FA including mezzanines >24000SF or if the FA is used for storage of commercial motor vehicles and >5000 SF.
B) Group B Business
No requirements for an ASPS.
C) Group A-2 Assembly (e.g. Cafeterias)
ASPS required IF the Fire Area (FA) >5000 SF or if the Occupant Load (OL) is >100 or if the FA is on a story other than the level of exit discharge.
D) Group A-3 Assembly (e.g. Conference Rooms)
ASPS required IF the Fire Area (FA) >12000 SF or if the Occupant Load (OL) is >300 or if the FA is on a story other than the level of exit discharge.

If the B, A-2 and/or A-3 do not meet these requirements and the Owner does not want to provide an ASPS in these areas, the building can be treated as separated, mixed OC. Per IBC Table 508.4, the S-1 OC w/an ASPS (S) would be required to be separated from the non-sprinklered (NS) OCs as follows :

S-1 (S) – B (NS) = No separation
S-1 (S) – A-2 (NS) = 2 Hour Fire Barrier (2FB)
S-1 (S) – A-3 (NS) = 2 Hour Fire Barrier (2FB)

If the entire building is to be protected with an ASPS, these OC separations are not required.

The title of this question (Concerns/Issues in Protecting All-Glass Atrium?) uses the term “atrium” which is not the condition here. “Atriums” are defined as “a vertical space that is closed at the top, connecting two or more stories in Group I-2 and I-3 occupancies or three or more stories in all other occupancies.” The condition you are referring to is a “two-story opening” (TSO) … see Section 712 Vertical Openings, 712.1.9 Two-story openings :

712.1.9 Two-Story Openings
In other than Groups I-2 and I-3, a vertical opening that is not used as one of the applications specified in this section shall be permitted if the opening complies with all of the following items:
1. Does not connect more than two stories.
2. Does not penetrate a horizontal assembly that separates fire areas or smoke barriers that separate smoke compartments.
3. Is not concealed within the construction of a wall or a floor/ceiling assembly.
4. Is not open to a corridor in Group I and R occupancies.
5. Is not open to a corridor on nonsprinklered floors.
6. Is separated from floor openings and air transfer openings serving other floors by construction conforming to required shaft enclosures.

The fire-resistance rated (FRR) protection of this TSO will be required based on 712.1.9 and possibly by the Type of Construction, specifically the FRR of the floor construction.

The “solution” to add a deluge ASPS to the glass surface of this TSO is not applicable since this only available for “atriums” per 404.6 Enclosure of Atriums :

404.6 Enclosure of Atriums
Atrium spaces shall be separated from adjacent spaces by a 1-hour fire barrier constructed in accordance with Section 707 or a horizontal assembly constructed in accordance with Section 711, or both.
Exceptions:
A fire barrier is not required where a glass wall forming a smoke partition is provided. The glass wall shall comply with all of the following:
1.1. Automatic sprinklers are provided along both sides of the separation wall and doors, or on the room side only if there is not a walkway on the atrium side. The sprinklers shall be located between 4 inches and 12 inches (102 mm and 305 mm) away from the glass and at intervals along the glass not greater than 6 feet (1829 mm). The sprinkler system shall be designed so that the entire surface of the glass is wet upon activation of the sprinkler system without obstruction;

Atriums have additional prescriptive requirements (e.g. smoke control) that will add additional costs so defining this as a “two-story opening” (TSO) is recommended.

Chris

11/1/2022 02:57:38 pm

It is my understanding that if an atrium is 55 ft or taller it does not require sprinkler protection, is this atrium that tall?

Concerns/Issues in Protecting All-Glass Atrium?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES