3 buildings on the same lot

[BayPointArchitect]

Applicable Code: 2006 IBCSection 705.3 (or whatever section relates to buildings on the same lot)New buildings (no existing buildings - all new)Type VB / Nonsprinkled.Given that there are three buildings - similar to what is shown in the illustration - what commentary reference can you provide that makes it clear the the imaginary line does NOT necessarily need to be exactly in the middle of the building structures?Please note that the combined aggregate total divided by the base allowable area is equal to 1.085 (over the allowable limit). Unless I am missing some allowable area increase for opening separation - as if the three buildings could take advantage of a 75% +/- increase around the group perimeter.Again, my main question is with regards to the arbitrary location of the imaginary line.Thank you,ICC Certified Plan ReviewerNFPA Certified Fire Plan Examiner

View attachment 2156

SeparatedBuildings-2.pdf

SeparatedBuildings-2.pdf

 

[zigmark]

You can always consider all three one building and take area increases for frontage at their perimeter. There is not allowable area increases for opening separations. Building area modifications are only allowed per Section 506. Are they sprinkled? Are you trying to figure out how they are in existence now or is this in design phase?

It appears you are saying they are Type VB construction (6510/6000 = 1.085)?

As long as the existing buildings remain complaint per Table 602,Table 705.8 and Table 716.5 that line can be wherever you would like. Moving the line may or may not have impacts depending upon type of construction, square footage, existing openings, opening protections, fire protection level provided etc..

The imaginary line is anything but arbitrary, your cited code section requires that it's location must be such that existing buildings remain code complaint.

ZIG

 

[mark handler]

http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_6_par002.htm

The imaginary property line can be at any location between the structures. Wherever the line is established, fire separation distance for each wall must be measured from the line, and wall and opening protection based on the distance to the assumed location.

 

[ADAguy]

Thanks MH, clear and concise.

 

[north star]

# : #

BayPointArchitect,

Are you sure that Section 705.3 is the applicable section ?

I am looking in Section 704.3 [ from the `06 IBC ]

See this link for multiple bldgs. on the same lot:

http://publicecodes.cyberregs.com/icod/ibc/2006f2/icod_ibc_2006f2_7_sec004.htm

# : #

 

[ADAguy]

06! ???? State that far behind?

 

[BayPointArchitect]

As Zigmark pointed out, the exception to 2006 IBC Section 704.3 (and 2009 IBC Section 705.3) allows all three buildings to be considered as "portions of one building if the aggregate area of such buildings is within the limits specified in Chapter 5 for a single building".

The base allowable area for A3 occupancy, Type VB construction is 6,000 S.F. per story.

Frontage increase = [F/P - 0.25] W / 30'

= [327'/327' - 0.25] x 30' / 30'

= [1 - 0.25] x 1

= 75% frontage increase of 4,500 S.F.

Therefore our allowable limit based on the most restrictive occupancy (A3) is 6,000 + 4,500 = 10,500 S.F.

We are only asking for an aggregate area of 6,513 S.F. for all three buildings = much less than the allowable 10,500 S.F. based on frontage increase.

And since there is no separation required between an A3 occupancy and another A3 occupancy, then the one-hour fire-rated walls (highlighted in orange for the sketch contained in the original post) are not necessary and there is no need to think about imaginary lines.

Am I correct in my thinking?

 

[zigmark]

I thought that was what you were getting at with that question.

You are indeed correct.

ZIG

 

[BayPointArchitect]

My main question is with regards to the arbitrary location of the imaginary line.

But I anticipated that the answer might be that the location of the imaginary line is irrelevant due to the frontage increase and aggregate area exception.

 

[BayPointArchitect]

Without fire-rated exterior walls to compartmentalize the three fire areas, my overall area of 6,513 S.F. is less than the 12,000 S.F. limit per IBC 903. No sprinkler required based on aggregate area. But would I then need to prove that my calculated occupant load is either less than 300 people or have those areas compartmentalized into three different groups less than 300 people each? Compartmentalized with fire-rated walls as shown in the original sketch and highlighted in orange?

 

[zigmark]

Yes the requirements out of Chapter 9 for fire protection are based on fire area, occupant load or level of exit discharge. Buildings not meeting fire separation distances to be considered separate buildings are all part of the same fire area unless further separated by one of the allowable methods described in the definition of fire area and meeting the required fire resistance rating of IBC Table 707.3.10 and having openings protected. This is where cost/benefit of fire sprinklers vs. fire separation becomes critical.

ZIG

 

[steveray]

Thanks MH, clear and concise.

Agree.....

 

[jwilly3879]

The fire area of the pavilions (if open sided) would be zero. Went through this on a project and the reviewer called for sprinklers because of the OL but it turned out to be incorrect.

 

[zigmark]

FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above.