Type of Sprinkler System for Group III Hangar?

7/2/2024

We have a airplane hangar that is over the 2,000 sqft threshold for a residential hangar, which makes it a Group III Hangar.

I'm having a hard time determining what fire suppression system would be necessary - would it be an NFPA 13 system?

It's not really clear in NFPA 409. Thanks for any help.

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6 Comments

Pete H

7/2/2024 06:44:39 am

Well it might be fortunate this is not in NFPA 409 for you:

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NFPA 13 (2016 Edition)

A.5.4.1 Extra Hazard (Group 1) occupancies include occupancies having uses and conditions similar to the following:

(1) Aircraft Hangars (except as governed by NFPA 409)

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That said, NFPA 409 (2016 edition) Chapter 8 "Group III Aircraft Hangars" probably still applies.

Especially the parts about if it is over one story, treat as per a Group II hangar, if protected with the fire protection specified in Chapter 7 [Group II hangars], provide the drainage specified in section 5.11

And

8.8 Fire Protection for Group III Hangars
8.8.1 Group III Fire Protection
8.8.1.1 Fixed fire protection system shall be installed where required and by and in accordance with local adopted building codes.
8.8.1.2 In addition to the requirement of 8.8.1.1, where hazardous operations, including fuel transfer, welding, torch cutting, torch soldering, doping, and spray painting are performed in any Group III hangar shall be protected with the fire protection specified in Chapter 7 and also meet the requirements specified in 5.4.2

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A.8.1.1 Group III hangars for small aircraft either are prefabricated assemblies or are locally constructed of unprotected steel or aluminum, light wood framing, or cement or cinder blocks. The majority of prefabricated types are unprotected steel structures with short steel or aluminum roof coverings and sidings. Other prefabricated hangars have wood or cement sidings and wood or plywood doors. Except in unusual circumstances, construction types other than Type II and Type V are unlikely because of cost factors. Earth floors are common. Floor drainage is not required unless the hangar is protected in accordance with Chapter 7, although utility drains are useful and should be provided. The airport operator should have a master key for the Group III hangars on the airport premises so as to provide emergency access in case of fire.

A.8.8.1.1 Not all adopted building codes require fire protection systems in Group III aircraft hangars. Various building codes have different requirements such as maximum area, height limitations, construction type limitations, setback distances, from property lines and other buildings, and fire protection features.

A.8.8.1.2 Fire loss history has shown that in aircraft hangars, regardless of size, if the fire event involves aircraft fuels, there is a significantly increased potential for loss of the hangar and contents if an automatic fire suppression system is not provided

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TL/DR: You might not have to protect it at all as per your locally adopted building codes. You might have to protect it as per a Group II hangar. Or you might just have to make it an NFPA 13 system protecting an Extra Hazard Group I occupancy. Depending on the construction type and requirements of your local building codes and/or if you're over 1 story, or if it has any of the items outlined in 8.8.1.2.

Anthony

7/2/2024 08:44:08 am

I agree with Pete here. NFAP 409 2022ed Ch 10 (group III hangers) references you back to the requirements of ch 9.

Glenn Berger

7/2/2024 08:26:40 am

Actually NFPA 409 does apply. In your case Section 10.8.1.1 says to provide fire protection systems where required by and in accordance with local codes.

This then typically kicks to the IBC, Section 311.2 Group S-1. Now to Area / Height / etc coverage in Chapter 5. And then from there you determine if fire sprinklers are required / desired. Then you provide such a system in accordance with NFPA 13.

Ricardo Gonzales Jr

7/2/2024 09:07:20 am

I know a major airport's AHJ (3rd busiest) has allowed the use of NFPA 409 for private jet hangers that are larger than private hangers. It was 1/10th the cost of replacing the AFFF at the time when no 3Fs were not yet approved. Environmental Dept pushed for the elimination of the AFFF without a viable replacement.

Jerry Clark

7/2/2024 10:17:02 am

When 409 refers to fixed fire protection systems required by locally adopted building codes, it's a default to what that local requirement might be. In this case, if you're an ICC state, Chapter 4 of the IBC,Section 412, Aircraft -Related Occupancies is your governing section. Group III hangars are required a water-only fire sprinkler system unless there are hazardous operations being performed (look at the list provided in 412.3.6.1).

Jack G

7/2/2024 10:41:15 am

I m the with Jerry. Most states are ICC so it would be good to check it out.
409 systems tend to be astronomical cost.
Ord Haz 1 in my opinion. Wet system.

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Type of Sprinkler System for Group III Hangar?

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