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Building Classification Types
When working on prefire plans (preincident for those who use that term) I ran into an issue that took most of the day to resolve.
Here is the situation:
Hanger 51 is both a hanger and office building. The center section (the hanger) is of typical Type II construction, light weight truss and I beam framing.
The roof is tongue and groove plank as are the exterior walls (not exactly noncombustible, but...)
The building is classified for inspection as a Type II
However the east and West walls of the hanger are closed in by 2 story wood frame with heavy fire loads. Both live and dead.
My job is to give the incoming CO a basis point to start his size up before getting to the scene.
If he leaves the barn thinking it is simply a Type II building and the fire is located outside the hanger bay he or she is behind the 8 ball when they arrive.
So what I would like to know is...in combination use structures would you go with the predominant structure type or the predominant fire load type when setting up your pre-fire plans?
Here is the situation:
Hanger 51 is both a hanger and office building. The center section (the hanger) is of typical Type II construction, light weight truss and I beam framing.
The roof is tongue and groove plank as are the exterior walls (not exactly noncombustible, but...)
The building is classified for inspection as a Type II
However the east and West walls of the hanger are closed in by 2 story wood frame with heavy fire loads. Both live and dead.
My job is to give the incoming CO a basis point to start his size up before getting to the scene.
If he leaves the barn thinking it is simply a Type II building and the fire is located outside the hanger bay he or she is behind the 8 ball when they arrive.
So what I would like to know is...in combination use structures would you go with the predominant structure type or the predominant fire load type when setting up your pre-fire plans?
Replies to This Discussion
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Permalink Reply by Tony P on
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The Preplan layouts I've used all allow for multiple use/structure. Your building would probably be described as an "Aircraft hanger with integral office space", The structural description would also describe the the outer shell and inner office building methods. Depends on the format used for the Preplan of course - yours may not allow this method?
If a multiple description can't be used in your format, I'd be inclined to describe the highest risk/load area first then add that the office space is located inside a Type II aircraft hanger.
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Permalink Reply by Christopher J. Naum, SFPE on
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The factors related to Fire Loading and Construction Type Classification are somewhat interdependent. Construction Type Classifications ( the type of structural support systems and envelopes) are defined by the degree of fire resistance and the degree of limiting exposure (vulnerability to fire exposure and degradation), this is then related to the allowable size (area of the structure) in square footage. Permissible fire loading is then relate to fire area related to degree of (structural) fire resistance there is.
A type II occupancy with a significant fire load should be of a pre-planning concern related to the fire loading firstand foremost; since the amount of materials (furnishing and structural systems) will dictate the required fire flows necessary, the amount of handlines (and GMP) that will be needed, manpower, apparatus etc. The hanger area would not be considered a significant concern since it has Type II construction, even with the T&G decking, a presumed large volume space and low fire loading. (low concerns related to fire behavior). The adjacent structure’s fire loading would be the deciding factor in formulating the pre-fire plan and calculating the required resources etc. for the various incident scenarios that you may be confronted with. Think worst case in terms of fire load/ fire dynamics and affects on structural fire resistance, degradation and compromise and FD resources…
Let me know if I can be of further help in this...........
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Permalink Reply by FETC on
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You state the exterior walls are T&G and the east/west walls are closed in by 2 story wood frame.
What is the actual structural framework components of the Hangar?
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I think he stated they were steel frame with lt. wt. bar joist trusses.....
That's what I based my response on...what are your thoughts?
"Hanger 51 is both a hanger and office building. The center section (the hanger) is of typical Type II construction, light weight truss and I beam framing".
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Permalink Reply by Allen Wahlstrom on
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Support structures are I Beam reinforced with lateral L beam supports.
The hanger is WWII era retrofitted in the late 1980's to look like the more modern hangers on base. A have corrugated fibreglass sheathing is boxing in the wooden exterior.
The office space is two stories with access at both ends and the middle entering the hanger on both levels and to the exterior with exits on 3 sides.
Exits are not an issue, nor is access to both decks.
I will take photos tomorrow and post them on here of the structure.
And guys...thanks!
Allen
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That'll be great...thanks
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