nfpa 13

[cdafd]

Using only nfpa 13 if an office building is 55,000 sq ft., one floor, but there is a two hour wall down the middle are you still over the sq ft that you are required two risers???

Once again using only nfpa 13

 

[TravisMack]

Yes. NFPA 13, to my knowledge, does not allow for 2 hr walls to separate a floor so that you don't need multiple systems in that size of a project.

It is my understanding that the system size limitation is based on maximum "allowable" impairments when a system is taken out of service for maintenance. Otherwise, in a wet pipe system, why not just have one system for 500,000 sq ft.

 

[stookeyfpe]

CDA:

I would say no. Section 8.2.1 (2) has the limitation of 52,000 square feet. However, it is not realistic to assume that the fire is going to extend from one separated compartment to another so long as the openings have adequate protection.

 

[pipedream]

two risers will be needed, 52,000 sq. ft. is the limit.

 

[firestop]

I do not think you need two risers, I think that NFPA 13 does not limit the number of floors that can be protected by a single riser, because each floor I think is considered a seperate fire area. However, limitations are placed on the area of each floor.

 

[TravisMack]

Firestop:

You are not limited to the number of floors that can be protected per riser. You also don't need control valves on each floor until you get into hi-rise buildings.

However, the initial post stated 55k sq ft on one floor. Therefore, 2 risers (or system control valve assemblies if you prefer).

I have had AHJs allow an increase in system areas in situations like this. We have typically been able to get 5-10% overages in system area from the AHJs.