System Protecton Area Limitations 1

[mx272]

There is a retail store that is 100,000 sq ft and two stories. There are vertical openings and sprinkler protection per 8.14.4 (nfpa 2002 ed), smaller ones with sprinklers around and the larger ones that do not require sprinklers. I am told that because of the larger vertical openings (that are not protected with sprinklers) I have to count the square footage on each floor to determine how many risers I need. I designed with 2 risers, they say 4 risers. Who is correct and why.
Thanks in advance.

 

[cdafd]

Interesting

How many sq ft per floor for clarification

 

[mx272]

100,000 sq ft.

 

[Jondoeiowa]

NFPA 13 2013 8.2

8.2.1 The maximum floor area on any one floor to be protected by sprinklers supplied by any one sprinkler system riser or combined system riser shall be as follows:
(1) Light hazard - 52,000 sq ft.
(2) Ordinary hazard - 52,000 sq. ft.
(3) Extra hazard - Hydraulically calculated - 40,000 sq ft.
(4) Storage - High-piled storage (as defined in 3.9.1.17) and storage covered by other NFPA standards - 40,000 sq ft

So if you have a retail store that would be Ordinary Hazard so you would need 4 risers to cover 2 systems per floor. If that helps.

 

[cdafd]

it appears that it is a correct call per black and white, just never seen it applied.

from the 2013 commentary:::


Where protection is required or where sprinklers are utilized in lieu of rated construction, vertical openings are assumed to be protected as outlined in 8.15.4.

Where multiple floors are not separate fire areas, and vertical openings are not protected, the total area protected by a single system on the multiple floors should not exceed 52,000 ft2 (4831 m2). In a single-story, 312,000 ft2 (28,986 m2) building of ordinary or light hazard occupancies, at least six systems would be required.

I guess one way to go back to two risers is provide opening protection, even though it may not be required???

 

[mx272]

This is going to open up a can of worms. There are a considerable number of buildings that have been designed only counting area's per floor with openings to the story or stories above. Offices, malls, apartment buildings and the list goes on.

 

[stookeyfpe]

It depends on the vertical opening. If it's a shaft and it's in my jurisdiction, the building code will dictate when fire-resistive separation is required. On the other hand, if it's atrium, we include the space when the vertical openings don't require opening protectives.

 

[cdafd]

Is the problem nfpa 13 vs a building code?

For instance a two story department store with large openings for whatever reason
Building code may allow them without any rating

But

Nfpa 13 says sprinkle protect some of them and others do not require them.
And it appears if nfpa 13 does not require opening protection on even one of them,than both floors have to be included in the maximum area allowed per riser???

 

[mx272]

It could be a problem with nfpa 13 vs building code. I am not versed at all in egress, fire ratings etc., but I would bet floor area does matter. Do the building codes make you count both floors when the vertical openings are not protected? I guess I am looking for consistency.

 

[SprinklerDesigner2]

While we are talking about size of systems what's the latest on FM Global? Was unlimited then I heard it went to 60,000 then back to unlimited again.

 

[skdesigner]

FM DS 2.0 2.4.1.6 Maximum Area of Coverage - The maximum area of coverage for a sprinkler system is limited only by (1) the hydraulic requirements of the sprinkler system's design and (2) the waterflow alarm requirements outlined in section 2.6.4.

Straight from the website, so I presume it's current.

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[stookeyfpe]

mx272:

What is the building code in your jurisdiction?

 

[SprinklerDesigner2]

mx272,

If memory serves me right the wording in NFPA #13 was different 35 and 40 years ago that allowed us to protect up to 52,000 sq ft per floor which allowed a single riser to protect up to 104,000 sq ft on two floors.

I know I wasn't alone in figuring it this way because nearly everyone did. Correction, everyone did it like that.

Back then our industry was insurance driven and whatever it was the insurance company (FM, ISO, Lumberman's or whatever) would buy we would do because nobody else looked at our sprinkler drawings.

For the first three years I was doing this I never once turned in a drawing to any government agency for approval. Strange as it sounds nobody in Ohio wanted anything to do with sprinklers.

I wasn't unusual for an insurance company accepting a pipe schedule system where the water supply was 55 static, 30 residual flowing 600 gpm because there take on it was "something is better than nothing" and that is exactly what they got.