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Allowable building area vs. Good old boy politics

Examiner

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Oct 22, 2009
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Good old boy politics,

Given: Existing School (Group E) of Type II-B construction with a fully automatic fire suppression system. One story building.

School has been in operation a year and is planning on additions to its structure. Floor plan shape/design is similar to a Y shape with a central entrance at the intersection of the V part of the Y. You could say the parts projecting from the center intersection are the classroom wings. Classrooms do not have additional doors to the outside at each classroom so unlimited area is out of the question. The School District will not put in additional doors either.

Allowable building area at time of CO: 14,500 Table 503 + 300 % spr + 75% perimeter = 68,875-sf

Actual building area at time of CO; 64,875-sf

Leaves an allowable addition to no more than 4,000-sf. Planned additions exceed 4,000-sf.

School district wants to add additional classrooms to two wings. Additions will exceed maximum allowable building area per floor.

Evaluations:

1. Firewall on one wing at the planned edition’s locations will reduce the allowable maximum building area of the existing building to below 68,875-sf. Leaving no room for the other wing’s possibility of any addition to the existing structure. The second wing cannot be added!

2. Firewall on each of the two wings reduces the allowable maximum area of the CO’d Building to less than is currently constructed. Say under 63,000-sf. Existing building is now in violation with new two firewalls!

3. Each abutment to the existing building using a firewall affects the existing building’s allowable area. I have confirmed this with Code Congress. Thus the reason why you cannot just put up a firewall every time you add onto a building.

4. Changing the existing Construction Type to a protected Type I-A or Type II-A is not an option.

Good old boy politics;

The owner is going to see the local Building Official to ask for a waver for adding additional classrooms to one wing and put a firewall at the other wing where more classrooms are planned to be added.

Remember, the one fire wall on one wing reduces the original building’s maximum allowable area where no other wings can be added even using a firewall at the other wings due to reduction of the maximum allowable area of the existing / CO’d building.

A wavier for two firewalls, if presented to the AHJ, reduces the existing / CO’d building’s allowable area to below the actual constructed existing building.

The owner will probably get his waiver request for the additional classrooms on the two wings.
 
I have seen interpretations where if the buildings on each side of a fire wall have full yards, everything gets maximum area increase. I don't necessarilly think that meets code, but it is more common than we think.
 
Additions to schools are the classic spot between the rock and a hard place. The evaluation for a code alternate needs to determine if the additonal area causes the safety afforded to the students and staff to be at least equal to what the prescriptive code requires. Schools generally have means of egress significantly better than code minimum. This can help offset a code alternate for additional area, especially if the building is sprinklered.
 
Can you drop a couple of fire walls in the existing portion say acroos the wings to break up the building into smaller areas?
 
Firewalls have to stand in place if the building collapes on either side of the firewall. Firewalls are not area separation walls, occupancy separation walls etc. When I was reviewing plans years ago under a older year NFPA 101, it was observed that the NFPA 101 allowed buildings to use area separation walls for building increases. They were not structural firewalls.
 
Examiner said:
Firewalls have to stand in place if the building collapes on either side of the firewall. Firewalls are not area separation walls, occupancy separation walls etc. When I was reviewing plans years ago under a older year NFPA 101, it was observed that the NFPA 101 allowed buildings to use area separation walls for building increases. They were not structural firewalls.
Agree however depending upon truss layout and other factors it may be possible.
 
Firewalls structurally are vertically cantilevered walls as I recall one structurally engineer's comment on these. The footings, subsequential construction of the wall to the bottom of the non-combustible roof deck alone would prohibit interior placement in an existing building due to cost. It would be better to just separate the buildings by the minimum required distance. The school does not have anything but one exit door on each of the end walls. No other openings. An enclosed connector would work but the owner wants to just add on with a firewall. Let's just violate the purpose of the Code's MINIMUM requirements when there is an alternate design consideration for the additions that does meet the Code and not affect the existing building's allowable area.
 
I would suggest you start looking at other issues that may be affected by this addition. Max. travel distance, common path travel and exit width with the added occupant load. This may add more weight to your argument.
 
Examiner,

Ever hear of "The Kingdom of the 152"? (i.e. - 152 separate school districts in the State of Mississippi ).

They get what they want.

As an aside to your question, ...are you the RDP for this project or are you just asking? RDP's usually

have a lot of control over "their" projects. Another option, if you are the RDP, is to back out of the whole

deal and wash your hands of it. Just saying.........
 
It is not that difficult to get a firewall in an existing building,I have seen it properly executed several times, improperly...more so....but I have seen it...we usually end up with it in our schools, in a former town, our HS was 3X over the allowable area with the sprinklers it DID NOT have....they added on...added sprinklers and 3 fire walls...
 
Examiner said:
Firewalls structurally are vertically cantilevered walls as I recall one structurally engineer's comment on these.
Examiner, help me understand the "cantilever" portion of that comment - - it implies (to me) that the wall must resist significant lateral forces (wind, earthquake, etc.)

However, IBC 706.2 only requires structural stability under "fire" conditions - no mention of wind or earthquake. If you could do parallel framing such that there was no roof or floor bearing loads, and with aluminum breakaway clips on such a wall, how much lateral force resistance would otherwise be necessary for a fire wall?
 
A structurally cantilevered firewall isn't necessary if the structural systems on each side are independent. The firewall can then have breakaway clips (or firecut joists as they did in the old days) on each side. It's usually difficult to pull an existing structural system apart and reconfigure it to achieve this independence.
 
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