Extend Sprinkler How Far Beyond a Service Area?

11/6/2024

I am trying to find how far to provide sprinkler coverage past the edge of the above-ceiling mechanical service area.

There will be mechanical units and duct work in this area, the floor is covered with 3/4" fire resistive plywood over metal studs. I would also like to know where to reference this in NFPA 13 for future use.

I attached the drawings for reference the hatched area is the service area. Thanks in advance.

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4 Comments

Pete H

11/6/2024 06:31:23 am

From NFPA 13 (2016 Edition)

11.1.2 Adjacent Hazards or Design Methods. For buildings with two or more adjacent hazards or design methods, the following shall apply:
(1) Where areas are not physically separated by a draft curtain, barrier, or partition capable of delaying heat from a fire in one area from fusing sprinklers in the adjacent area, the require sprinkler protection for the more demanding design basis shall extend 15 ft (4.6 m) beyond its perimeter.
(2) The requirements of 11.1.2(1) shall not apply where the areas are separated by a draft curtain, or barrier located above an aisle, where the aisle has a minimum 2 ft horizontal seprateion from the adjacent hazard on each side, or a partition that is capable of delaying heat from a fire in one area from fusing sprinklers in the adjacent area.
(3) The requirements of 11.1.2(1) shall not apply to the extension of more demanding criteria from an upper ceiling level to beneath a lower ceiling level where the difference in height between the ceiling levels is at least 2 ft located above an aisle, where the aisle has a minimum 2 ft horizontal separation from the adjacent hazard on each side.

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If you're in a noncombustible above ceiling space that would not normally require protection without fuel fired units:
At least 15'-0", probably to the walls though (AHJ might allow 15'-0" based on the passage above, but I'd still advise to the walls as if you're protecting a room, you should just be protecting a room). And it might be cheaper just to put some sheet rock up and put walls around the mechanical space to not have to protect the whole area.

If you're in a combustible space and just figuring where to switch from the ordinary hazard mechanical space to the light hazard unoccupied space, 15 feet of additional ordinary hazard protection around the perimeter should apply.

My two cents, take it with a grain of salt.

Dan Wilder

11/6/2024 07:13:23 am

In these cases, I have always referenced 13-19'-9.3.14.3 and figured the distance as 0.6√Remote Area for extension of coverage into an area that does not require it (but no less than 24' per 9.3.14.3.1)

I will also review any full height walls and structure as that will further define the final outline.

Franck

11/6/2024 08:08:08 am

I am using the same references as Pete

Only exception : with hydraulic oil (and similar equipment) where you expect an oil spray fire, I am using 20 ft (6 m). This comes from FM Global.

And if you expect a combustible/flammable liquid spill fire, you need to protect the entire bonded area (if extends more than 15 ft)

Glenn Berger

11/6/2024 08:43:55 am

Is your question based upon a Mechanical Equipment Room that does not have full height walls at its perimeter and then how far do you need to extend sprinkler piping into the adjacent above ceiling space?

If this is the case, then a complete above ceiling sprinkler system is required. I would recommend that you get the architects to complete the walls to extend from the floor to the deck above.

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Extend Sprinkler How Far Beyond a Service Area?

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