Height of Sprinkler Underneath Seating Bowl?

12/13/2021

We need to provide sprinkler protection below the seating area of a hockey rink.

The frame for each seat is 2'-10" wide, and 2'-0" high, and slopes down towards the ice rink. The floor area covered varies depending upon the location and ranges from 5-ft to 15-ft.

Our designer has shown sidewall sprinklers with the deflector parallel with the slope, at the high point of the underside of the bowl. The problem is the deflector needs to be more than 2'-0" below the frame in order to not be obstructed by the seating risers below.

Obviously there are no sidewall sprinklers approved for this arrangement.

If we use uprights instead of sidewalls, these will also need to be more than 2'-0" below the framing and I don't see this meeting the requirements of obstructed construction (thus allowing us to be 22-inches down to the deflector).

Is there something in the code that will allow us to cover this area with upright sprinkerls, 22-inches below the framing, with deflectors parallel to the slope?

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7 Comments

Dan Wilder

12/13/2021 08:19:06 am

The description leads me to think you have more of a "stair step" look to the seating (ceiling/roof deck). If this is the case, I would create a "line" connecting the bottom & top edges of the stairs (along the slope)...22" from that upper diagonal and 1"-6" below the lower line is the sweet zone. I would also not put the upper sprinkler lower than 36" from the peak and keep the clear horizontal distance for the steep slope.

I would stay away from sidewalls and would space the uprights horizontally more aligned with a wood structure (8' to 10' on center max). I've done something similar beneath concrete seating stadiums.

Alex

12/13/2021 08:40:19 am

To follow off of Dan's response, if your seats are as Dan described, I cant think of a sidewall that is listed for that type of application. I think uprights are the only way to go.

Jesse

12/13/2021 09:22:47 am

Agree with Dan and Alex. I can't think of a HSW sprinkler that would be appropriate for this.

sean

12/13/2021 10:42:31 am

I would say this should be handled before the design, go the engineering team or to the AHJ and have a discussion

James Phifer

12/13/2021 11:53:37 am

The only time we use sidewalls under seating is when we have telescoping bleachers. Otherwise, we use uprights. But I agree with Sean, the AHJ or Engineer should be consulted.

Anthony

12/13/2021 12:15:48 pm

I agree with the rest of the comments about spacing up right heads it sounds like combustible obstructed construction with a sloped ceiling.

Make sure you're using the appropriate remote area. (11.2.3.2.4) NFPA 13-16ed

Also make sure the sprinklers aren't over spaced. Combustible obstructed construction reduces the maximum protection area of each head even in light hazard. (Table 8.6.2.2.1(a)) NFPA13-16ed

With regards to sidewall heads you'd need one specifically listed for obstructed construction.

NFPA 13-2016 8.7.4.1.1.2 says you can only use sidewalls that are below 6'' - 18'' from the ceiling with a specific listing.

Jay

12/14/2021 09:51:39 am

Finish the bottom of the seats/stairs with a noncombustible material so that you have a smooth, unobstructed, sloped surface, and install sprinklers accordingly.

Height of Sprinkler Underneath Seating Bowl?

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