Unlimited Area 507.2 and Buildings on the Same Lot 503.1.2

[YongMNLad]

2012 IBC
I'm getting caught up on some language in the 2012 IBC. In Section 503.1.2 it states that two buildings may be regulated as one building if the building area is within the limitations of 503 as modified by 504 and 506. It does not, however, mention the "modifications" of 507.

507.2 allows an one-story S-2 building with at least 60' clear yard to be unlimited area.

I am curious of others' interpretation of this and whether it would be allowed to consider two unlimited area S-2 buildings as the same building.

I have attached a sketch of the scenario in question.

 

[steveray]

You could have 11 buildings on the same lot if they all work as unlimited....

 

[fatboy]

I concur with Steve ray....

 

[JBI]

I must take the opposing viewpoint here...
503 specifically recognizes the modifications in 504 and 506.
If the intent were to allow multiple unlimited area buildings to count as one then 503 would also cross reference 507.
Since it does not one would be limited to using 507 for a single building only.
As a practical matter it forces the described situation to use a construction classification that already allows 'unlimited area'. With some exceptions, type IA and type IB generally allow UL for area in table 506.2.

 

[steveray]

Good point....
I guess the question there then is does 506.4.1 ( as modifications per 506)get you there? I think that is our take..

506.4.1 Area determination. The total allowable building
area of a single occupancy building with more than one story
above grade plane shall be determined by multiplying the
allowable building area per story (Aa), as determined in Section
506.1, by the number of stories above grade plane as
listed below:
1. For buildings with two stories above grade plane, multiply
by 2;
2. For buildings with three or more stories above grade
plane, multiply by 3; and
3. No story shall exceed the allowable building area per
story (Aa), as determined in Section 506.1, for the occupancies
on that story.
Exceptions:
1. Unlimited area buildings in accordance with Section
507.

 

[mtlogcabin]

2012 IBC

I am curious of others' interpretation of this and whether it would be allowed to consider two unlimited area S-2 buildings as the same building.

No, not without the open space requirement between the two buildings

07.1 General.
The area of buildings of the occupancies and configurations specified in Sections 507.1 through 507.12 shall not be limited.

Exception: Other occupancies shall be permitted in unlimited area buildings in accordance with the provisions of Section 508.2.

Where Sections 507.2 through 507.12 require buildings to be surrounded and adjoined by public ways and yards, those open spaces shall be determined as follows:

1. Yards shall be measured from the building perimeter in all directions to the closest interior lot lines or to the exterior face of an opposing building located on the same lot, as applicable.

2 Where the building fronts on a public way, the entire width of the public way shall be used.

 

[YongMNLad]

Thanks for the discussion. These are the exact thoughts I was debating with myself in my head...

The commentary in 507.1 states "Two unlimited area buildings on the same lot must be separated by 60 feet unless they are treated as a single building under the provisions of Section 503.1.2"

 

[mtlogcabin]

I disagree with the commentary. The code does not reference Section 507 when applying 503.1.2.

503.1.2 Buildings on same lot.
Two or more buildings on the same lot shall be regulated as separate buildings or shall be considered as portions of one building if the building height of each building and the aggregate building area of the buildings are within the limitations of Table 503 as modified by Sections 504 and 506. The provisions of this code applicable to the aggregate building shall be applicable to each building.

 

[steveray]

Put a roof between them and it works (as one unlimited), take it away and it doesn't?....Stupid......Where is the safety or risk in any of that?

 

[Builder Bob]

Interestingly, the concept of all buildings acting as one also means fire protection systems are considered as for one building unless separate fire areas exist ----- it makes the FSD of Table 602 harder to enforce and creates all sorts of confusion on future projects - especially as codes change over time.

 

[steveray]

Yeah but, I don't believe you get UL area without sprinklers I don't see where the future confusion comes from....

 

[Builder Bob]

When people try to add an A 2 to a group if buildings that are on the same parcel.....that are non sprinklered in the first place but in a building the fire area would trigger fire rated separation or fire sprinklers

 

[steveray]

Change of use in any building will/can throw a monkey wrench....Less than 10%? Accessory? I guess we just don't run into that nonsprinklered 1 story UL area S or F here. Maybe they think the 12,000 ft fire area thing is not worth it?

 

[Builder Bob]

I don't know, but this section of the code makes sense when doing new construction, is a donkey (sorry if I offended any donkeys or donkey lovers ) when somebody takes a 4500 SF stand alone building and discover the occupant load or occupancy will create or cause a fire alarm to be installed in all buildings

 

[WRB]

Along these same lines of confusion, if I had four small detached buildings on the same lot built using same type of construction (VB), the same occupancy (M) and the same size, can the required separation between buildings be 4'-0" as compared to Table 602? Do I need fire rated exterior walls at separation locations as noted in Table 602 ? Are windows not permitted on these walls as noted in Table 705?

 

[ADAguy]

"Amazing" talk about multiple ways to "skin" a cat!
You need to be an English major and an FPE to support out this language.

 

[mtlogcabin]

Yeah but, I don't believe you get UL area without sprinklers I don't see where the future confusion comes from....

F-2 and S-2 can be unlimited and non-sprinkled

507.2 Nonsprinklered, one story.
The area of a Group F-2 or S-2 building no more than one story in height shall not be limited where the building is surrounded and adjoined by public ways or yards not less than 60 feet (18 288 mm) in width.

 

[WRB]

The last sentence in 503.1.3, Buildings on Same Lot, is the basis for the above question. It states "The provisions of this code applicable to the aggregate building shall be applicable to each building." Four separate buildings or one aggregate building?

 

[Builder Bob]

The use of allowing multiple buildings as one building is the same as building one building with four tenant spaces - however, this provisions creates headaches when modifications or changes of use involve one of the buildings on the lot.

I then have to review the plans as if the space was located in one building, so fire separations, fire sprinklers, fire alarm and so forth may become required.

 

[Francis Vineyard]

Your results may vary: Multiple Buildings on the Same Lot

 

[Builder Bob]

Imaginary lot lines would not apply if the separate buildings are considered to be one building as allowed by 507.2 (503.1.2 - 2015 IBC). The exterior fire rating by T602 . 705, etc. would apply only to the walls along the exterior footprint as if it was one building. No fire separations, fire alarms, fire sprinklers or any fire ratings are required unless the aggregate of the occupants, total fire area, etc. exceeded the requirements or the thresholds as established by code in other sections. However; alterations to building 4 may have an impact on the remaining buildings is the thresholds are exceeded.

This is the trade off allowed by this section. Each building is not a standalone building and would basically be looked upon as a tenant upfit for the "single Larger" Building. Thresholds for fire protection features would still be the same as if all 7 buildings in this example were in one building.