Sprinkler omission/design?

[steveray]

Guys,
Same building we have been dealing with and you have seen comments/ questions before. 2003 IBC and 2002 or 2010 NFPA 13 apply (don't think it really matters) 2010 sections referenced I believe...


4 story, wood fame (VA), R2 building, full 13 system. They have omitted sprinklers in the combustible space per 8.15.1.2.6 and NFPA’s interp. (my previous post was about the construction of the metal furred floor/ceiling) Problem is that they didn’t take the fire loading/ water demand of the concealed space into account per 11.2.3.1.4(3)….Which then refers you to 11.2.3.1.4(4) for allowable exceptions.


11.2.3.1.4(4)(j) is very similar to the requirements of 8.15.1.2.6 for allowing the exemption of coverage, but is very specific on ½ gyp board or equivalent for firestopping when exempting from designing the system for those concealed spaces whereas 8.15.1.2.6 says equivalent to the joist web (in this case 7/16 OSB)…..


I believe the FM and I both don’t love this design, so we just want to make sure we have our I’s and T’s in order….


The IBC allows structural sheathing, for fireblocking but at 0.719 inch….not 0.4375 (7/16”)….


718.2.1 Fireblocking materials. Fireblocking shall consist

of the following materials:

1. Two-inch (51 mm) nominal lumber.

2. Two thicknesses of 1-inch (25 mm) nominal lumber

with broken lap joints.

3. One thickness of 0.719-inch (18.3 mm) wood structural

panels with joints backed by 0.719-inch (18.3 mm)

wood structural panels.

4. One thickness of 0.75-inch (19.1 mm) particleboard

with joints backed by 0.75-inch (19 mm) particleboard.

5. One-half-inch (12.7 mm) gypsum board.


Trying to determine if NFPA is looking for fireblocking at 160 cuft. or designer is leaning towards draftstopping. This will decide whether or not they need to fully insulate the 24" deep floor ceiling cavities of a 4 story 80 unit apartment building....
.

Any input?......Did I mention that would be a really expensive change order?

 

[cda]

Looks like NFPA 13 is tougher, and to me they are required to meet all requirements, if they want to use the NFPA 13 exception for no sprinklers.


I kind of hate building design in NFPA 13, when a building designer doe not know anything about NFPA 13.


Sounds like they need fire stopping and shall be 1/2 inch, or equal.


(4)
The following unsprinklered concealed spaces shall not require a minimum area of sprinkler operation of 3000 ft2 (279 m2):

A.11.2.3.1.4(4)(j) The gypsum board (or equivalent material) used as the firestopping will compartment the concealed space and restrict the ability for fire to spread beyond 160 ft3 (4.5 m3) zones covering multiple joist channels.

 

[cda]

Am I missing something in the question?


Those are some large unprotected void areas!!!!

 

[steveray]

Thanks CDA!....Anyone else?

 

[steveray]

160cuft each.....no limit in NFPA that I am aware of....

 

[cda]

You can always ask for a third party Fire Protection engineer to evaluate the entire set up, at owners expense.

 

[steveray]

I think it will be at the building designers expense.....

 

[IJHumberson]

Looks to me like they have to provide the 1/2-inch gyp board (or equivalent) firestopping or design the sprinkler demand for the added amounts per the concealed space.

 

[tmurray]

Agree with everyone else, looks like they've decided to firestop with 1/2 gypsum by going this route.

 

[steveray]

^^^^The problem is they would be drywalling every joist as the joist bays are around 114sqft each....If there has to be a physical change, they will be filling the cavities with insulation I imagine. I was trying to get a feel for you NFPA guys and how you felt about NFPA using "firestopping" vs. ICC "fireblocking" or "draftstopping" and where those all lined up? The designer of course is saying DS is the intent, because then the web becomes equivalent per ICC. I say FB is the intent and 7/16 OSB is not equivalent...

 

[cda]

Would say follow NFPA 13

I guess osb does not make it into 722 of IBC

The other thing 13 does not specify the type of Sheetrock to be used, as in plain o vs type X

 

[tmurray]

You can't mix and match requirements from different standards. The designer should have read the whole code section when spec'ing the project out. The standard says 1/2 gypsum or equivalent, but does not provided how to measure equivalency. Ultimately, it would be up to you as the AHJ to determine what is equivalent, but personally I would have them provide evidence that the web is equivalent from a fire perspective. I'm not helping someone out of a mess they've put themselves in without them doing some work too.

Education is expensive you can either take courses and avoid mistakes or make mistakes and pay for the consequences.

 

[steveray]

Kind of my thoughts too TM....I just like to check and see if anyone else has a different perspective than me or some hard info. I will help wherever I can, but I am not going to stretch to fix their mistake...