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IFC Fire Flow

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TravisMack

TravisMack

Mechanical
Sep 15, 2003
1,757
Have a project where the architect is using area separation walls to create separate buildings from one large building. It is allowing the system to be a 13R system by doing that - which is what the architect intends. However, a question has risen in regard to Appendix B.

Appendix B says something like the area separations with fire walls without openings. Now, I don't want to sound completely stupid, but can you have a rated fire door in that area separation wall?

It becomes and issue because this jurisdiction has amended the fire code to only permit a 50% reduction in required fire flow for an NFPA 13 system and there is no reduction allowed for a 13R system.

If the area separation walls are not permitted to have openings, then this system would have to be a 13 system because we would need the reduction to meet site fire flow requirements.

We have a meeting about this later in the week. I am not an IFC/IBC expert by any means. How do those on this forum with experience in this area view the issue?

Travis Mack
MFP Design, LLC
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Is the enitire building a "R" occupancy?

But you are saying no matter what a 13R gets no reduction in that ahj, so do you need to do a 13 system anyway?

 
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The entire building is "divided into 7 buildings" via area separation walls. 6 of the areas are under the required area to allow a 13R system. 1 area will have a 13 system.

The issue that may throw a monkey wrench is IFC Appendix B: B104.2 Portions of buildings which are separated by fire walls without openings, constructed in accordance with IBC are allowed to be considered separate fire flow calculations areas.

These area separation walls have a rated door at the corridors. Does that violate the "fire walls without openings," or is the rated door permitted?

If that doesn't violate, the site water flow can meet the flow required of an individual area. But, if the rated door is not permitted, then we don't have it. The total building is >190k sq ft. That requires 8000 gpm at 20 psi. Our water flow test only has about 4500 gpm at 20 psi. If the individual areas are allowed, then those have fire flows under 4000 gpm @ 20 psi per Appendix B.

It is just a big difference if we protect the entire "building" as 13 vs 13R. The architect is from out of state and was not fully aware of the amendments to the IFC that only allows a reduction for NFPA 13 systems. Typically this would not be an issue because the IFC allows a 75% reduction for 13 or 13R systems.

But, the question is out there if "fire walls without openings" means that you can't have rated fire doors.

Travis Mack
MFP Design, LLC
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Have not delt with this section,

The IFC commnetary backs up "NO" openings, and adds that it is a "Specific" requirement that overrides the IBC.

Has the AHJ been asked the question about openings??? since they reduced the flow allowance, they might allow the openings. And not sure what rating the doors were proposed to be, but the desinger might bump them up to equal the rating of the wall, and see what the ahj says.


 
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TravisMack:

The appendices of the code are not a mandatory part of the code unless they are specifically adopted by the jurisdiction. You might want to verify this with the building department - it may give you some wiggle room.

Regards,

DB
 
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Travis:

Sorry to be late to the event but I'm have been hammered at work.

Your jurisdiction has adopted Appendix B, and amended it. We do the exact same thing, which is actually prudent because everyone know the rules. Before I go deeper into this I am assuming this is some form of a City In The Box and the architect, rather than employing IBC Type III construction chose to break the building up with many fire walls to keep the construction Type V-A. I will also be using the 2012 IFC to respond to this question. I also am going to assume the corridors do not have conditioned air because they are open, so smoke detection is not an option. One more thing: area separation is a legacy Uniform Building Code term, so unless this is a UBC building, the correct term is a FIRE WALL not an AREA SEPARATION WALL.

The IBC has always allowed openings in fire walls. When I worked for ICC I told many people I could not justify the basis for Section B104.2 and I still can't. It's perfectly permissible and in your client's building I suspect the architect is using the fire wall openings as Horizontal Exits. IBC Section 716.5.9.3 requires hold open devices on these doors which can be easily made to release upon sprinkler activation.

I have a couple of options but your architect is probably not going to like any of them.

1) Construct all fire walls using strictly noncombustible materials with the lowest thermal conductivity (i.e., concrete). The IBC allows wood frame fire walls, and these are perfectly acceptable. However the introduction of true noncombustible construction does reduce the available fuel load.

2) Change the construction type in the largest buildings to Type IIIA. The IFC fire flow requirements are silent on mixed construction buildings and in these cases I have applied the mixed use ratio equation in IBC Section 506.1.

3) Accept the fact that fire flow is not available and protect the building per NFPA 13.

At this point I am going to step away because I've spent an hour looking at this problem and I'm not being paid for this free experience. I hope you are.
 
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Scott:

Thanks for your time. I was hoping you would happen to check in on this one. Yes, this is in your former jurisdiction. :)

I find it interesting that the meeting has yet to happen with the architect and GC to go over this issue. Your assumptions are just about dead on. Hey...I think you have done this once or twice before....

I think the GC is wanting to move forward with an NFPA 13 system as it just solves all sorts of issues. It seems to be the architect that is pushing for an NFPA 13R system. I really don't care, we can draw it however. 13 just means I have a few more circles on the plan than 13R. My customer is fine with either. He gets more $$ for a 13 but already has the job as 13R.

I'll let you know how it plays out.

Travis Mack
MFP Design, LLC
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T-Mack:

I've sat across the table in so many meetings discussing this issue. Lets face it: the developer made the call on going cheap and because he was a schmuck, he chose Type V-A construction and believed he solved all the problems with some extra gypsum wall board and rated doors. If he would spent $20K on a real fire protection engineer, either of us could have engineered this to meet fire flow, employ a 13R system, and saved him some money.

As a point of information, the issue of permissible fire flow reductions in Appendix B of the 2015 IFC is moot. Unless the jurisdiction amends Appendix B, the maximum reduction anyone will get is 25%. You wanna talk about a cost killer that provision will be it, especially with these maga Cities in A Box or any Group S-1 High Piled Combustible Storage warehouse in Type V or III buildings, which is pretty much everything in your time zone.
 
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