# Classifying multiple buildings as one



## Mech (Nov 8, 2012)

2009 IBC

Proposed 7,100 sf type IIB, Group B occupancy being built within 10 feet to an existing 5,200 sf type IIB building, also Group B occupancy.  No fire rated walls, doors, assemblies, etc.

The aggregate area will be 12,300 sf.

There is an S-1 storage area in the new building, not separated from the rest of the new building.

*903.2.9 Group S-1.* An automatic sprinkler system shall be provided throughout all buildings containing a Group S-1 occupancy where one of the following conditions exists:

1. A Group S-1 fire area exceeds 12,000 sf.

2. omitted

3. omitted

4. omitted

Must the buildings be sprinklered since the aggregate area exceeds 12,000 sf, making the fire area exceed 12,000 sf?

Thoughts?

Thanks.


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## mtlogcabin (Nov 8, 2012)

> The aggregate area will be 12,300 sf


No it is not. You have 2 fire areas

The exterior walls are not required to be rated except by Table 602 and then you assume a property line and rate the new construction only

[F] 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.


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## Mech (Nov 8, 2012)

Thanks MT.  I failed to re-acquaint myself with the definition (the defining boundaries.)


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## Coug Dad (Nov 9, 2012)

If they are on the same property, the two buildings may be classified as one building.  503.1.2.


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## brudgers (Nov 9, 2012)

Mech said:
			
		

> 2009 IBC  Proposed 7,100 sf type IIB, Group B occupancy being built within 10 feet to an existing 5,200 sf type IIB building, also Group B occupancy.  No fire rated walls, doors, assemblies, etc.  The aggregate area will be 12,300 sf.  There is an S-1 storage area in the new building, not separated from the rest of the new building.  *903.2.9 Group S-1.* An automatic sprinkler system shall be provided throughout all buildings containing a Group S-1 occupancy where one of the following conditions exists: 1. A Group S-1 fire area exceeds 12,000 sf. 2. omitted 3. omitted 4. omitted  Must the buildings be sprinklered since the aggregate area exceeds 12,000 sf, making the fire area exceed 12,000 sf?  Thoughts?  Thanks.


  why on earth would anyone propose those buildings as IIB rather than VB?


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## Mech (Nov 9, 2012)

> why on earth would anyone propose those buildings as IIB rather than VB?


1. Group S-1 Type VB construction is limited to 9,000 sf while IIB is allowed 17,500 sf.

2. (Some) insurance carriers will give a lower rate to owners with non-combustible construction as opposed to combustible construction.

3. If the owner wishes to add another building in the future, reference can be made to these plans to determine existing building type instead of explaining the different types to the owner and figuring out the classification again.

There is a method to my madness.


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## brudgers (Nov 9, 2012)

Mech said:
			
		

> There is a method to my madness.


  I may have to try that.


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## Builder Bob (Nov 12, 2012)

I thought when you classified multiple buildings as one that all requirements for the "single" building had to meet the requirements of the code for the footprint of a single building. The final sentence of 503.1.2 states" The provisions of this code applicable to the aggregate building shall be applicable to each building."

In other words, if the fire area exceeds 12,000 SF in the aggregate building, occupancy separation must be used or a fire sprinkler system would be required. Although the definition of fire area is right on in this topic, the application is not. (definitions are general, this code section is specific)


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## AegisFPE (Nov 12, 2012)

Bob spells out the code pretty clearly, the 2 structures are 1 building, consider if they were just 1 foot apart...eventually, we get to assuming a lot line per 705.3.

I would be curious if the aggregate S-1 area would satisfy the allowable area for an accessory space (10% of the total building area per 508.2.1) such that the building could be considered 100% Group B.


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## kilitact (Nov 13, 2012)

AegisFPE said:
			
		

> Bob spells out the code pretty clearly, the 2 structures are 1 building, consider if they were just 1 foot apart...eventually, we get to assuming a lot line per 705.3.I would be curious if the aggregate S-1 area would satisfy the allowable area for an accessory space (10% of the total building area per 508.2.1) such that the building could be considered 100% Group B.


Accessory use would still require that the S-1 area be under 12,00 sq ft or separated into smaller fire area. The two buildings have exterior walls which will separated them into smaller fire areas.


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## Builder Bob (Nov 13, 2012)

No, the fire area would be considered the footprint of the two buildings which are now considered one building........
	

	
	
		
		

		
			





The single building now has a 17,000 SF footprint since it is now (one) aggregate building instead of two separate structures.


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## kilitact (Nov 13, 2012)

Builder Bob said:
			
		

> No, the fire area would be considered the footprint of the two buildings which are now considered one building........
> 
> 
> 
> ...


Buildings on the same lot in section 503.1.2, doesn’t delete the exterior walls of each building, which would be as defined in section 1402 definition of exterior walls. This building is enclosed and bounded by exterior walls which meet the definition of fire area in section 902.


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## AegisFPE (Nov 13, 2012)

Kilitact, you've got me with 508.2.2 for occupancy classification of the accessory space. The accessory provisions address height and area, but the fire area issue remains.

Bob has you on 503.2.1, as the exterior walls do not satisfy Section 705.5 or Table 602 where there is no lot line assumed between the buildings.

I would buy what you're selling it if the new building were 1-hour with no openings (per Tables 602 and 705.8) as if on an imaginary lot line, and the existing building at least 10 feet away had maximum 15% openings in the portion of the wall that faced the new building.

Otherwise, from what you're saying, instead of 10 feet apart they could be say 3 feet apart, with unlimited openings and nonrated exterior walls. Without sprinklers, there is no effective fire separation. How far apart do they have to be to use the exterior wall to establish a separate fire area? See Tables 602 and 705.8.


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## kilitact (Nov 13, 2012)

AegisFPE said:
			
		

> Kilitact, you've got me with 508.2.2 for occupancy classification of the accessory space. The accessory provisions address height and area, but the fire area issue remains.Bob has you on 503.2.1, as the exterior walls do not satisfy Section 705.5 or Table 602 where there is no lot line assumed between the buildings.
> 
> I would buy what you're selling it if the new building were 1-hour with no openings (per Tables 602 and 705.8) as if on an imaginary lot line, and the existing building at least 10 feet away had maximum 15% openings in the portion of the wall that faced the new building.
> 
> Otherwise, from what you're saying, instead of 10 feet apart they could be say 3 feet apart, with unlimited openings and nonrated exterior walls. Without sprinklers, there is no effective fire separation. How far apart do they have to be to use the exterior wall to establish a separate fire area? See Tables 602 and 705.8.


Not selling just regurgitating code.

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.

 There is no separation distance given, only that it be an exterior wall. The fire rating based on distance of the exterior walls to buildings, lot lines would be in accordance with sections 705 and table 602. What you’re trying to suggest is that an exterior wall that is defining a fire area would need to be rated based on distance to property of other buildings, which is not correct.


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## Builder Bob (Nov 13, 2012)

Although the definition of fire area is right on in this topic, the application is not. (definitions are general, this code section is specific)


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## Builder Bob (Nov 13, 2012)

2012 IBC

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.

In other words, if multiple buildings can be built within the area limitations of T 503, they may be considered as one building. However, any other code related provisions shall applied to all buildings..... for example, fire sprinkelr system when storage exceeds 12,000 SF, then all buildings would have to be sprinkled or separated by occupancy separations to eliminate the sprinkler system.


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## mtlogcabin (Nov 13, 2012)

If you do not accept the exterior walls for creating two separate fire areas then Table 707.3.9 is your only option when dealing with fire areas in an aggregate single building under 503.2.1

An "S-1" requires 3 hour fire barrier

A "B" requires 2 hour fire barrier

I would assume a property line of 10 feet from the existing building and rate the new exterior wall in accordance with 602 and not consider them one building



> 2. (Some) insurance carriers will give a lower rate to owners with non-combustible construction as opposed to combustible construction





> There is a method to my madness. :grin:


Yes but your method and the insurance companies madness are not the same

Insurance companies use ISO classifications to determine if a building is combustible construction and they are not on par with the building codes.


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## kilitact (Nov 14, 2012)

Builder Bob said:
			
		

> 2012 IBC 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.
> 
> In other words, if multiple buildings can be built within the area limitations of T 503, they may be considered as one building. However, any other code related provisions shall applied to all buildings..... for example, fire sprinkelr system when storage exceeds 12,000 SF, then all buildings would have to be sprinkled or separated by occupancy separations to eliminate the sprinkler system.


If the storage area (S-1) exceeds 12,000 sq ft than it would have to be sprinkled or separated into smaller fire areas (less than 12,000 sq ft). This would take you to the requirements for fire areas i.e exterior walls etc. If the two buildings were separated by 78 feet would you require fire barrier construction in place of the exterior wall? Do you consider the exterior wall has an interior wall?


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## TJacobs (Nov 14, 2012)

_2006 IBC Section 702.1 Definitions:_

_FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or fire-resistance-rated horizontal assemblies of a building._

The exterior walls should make separate fire areas assuming rated exterior walls and opening protectives in accordance with Table 706.3.9.


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## AegisFPE (Nov 14, 2012)

So looking at Building A and Building B above, where the exterior wall of each building was nonrated construction and contained unlimited unprotected openings, where the separation between the buildings was 6 inches, you would conclude that those were separate fire areas?

If you are going to rest on the definition of a fire area being defined by exterior walls, then you must simultaneously accept that the exterior walls shall comply with Section 705.

These walls do not comply with Section 705, and are therefore not exterior walls as anticipated in the definition of a fire area. These are perhaps "intermediate weather protection partitions" that are part of a single building that happens to have a detached addition. This is treated as one building as addressed in 503.1.2.


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## kilitact (Nov 14, 2012)

Where exterior walls serve as a part of a required fire-resistance-rated shaft or exit enclosure, or separation, such walls shall comply with the requirements of Section 705 for exterior walls and the fire-resistance-rated enclosure or separation requirements shall not apply.


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## AegisFPE (Nov 14, 2012)

I don't think 707.4 helps, because though it waives the fire-resistance requirement of the fire-resistance-rated enclosure, it prescribes compliance with Section 705, including appropriate fire-resistive construction and opening protection requirements of 705. You're not going to tell me I can have a stair with a nonrated exterior wall built on the property line? Section 707.4 is trying to say that the fire barrier need not need to interrupt the exterior wall, not that the exterior wall of an exit enclosure need not be rated.

I think Section 705.3 is more applicable to the subject discussion, which states: _"Where a new building is to be erected on the same lot as an existing building...the existing building shall be such such that the exterior wall and opening protection of the existing building meet the criteria as set forth in Sections 705.5 and 705.8. __*Exception:*__ Two or more buildings on the same lot shall either be regulated as separate buildings or shall be considered as portions of one building..."_

The exception goes on to explain: _"Where the buildings contain different occupancy groups or different types of construction, the area shall be that allowed for the most restrictive occupancy or construction."_ Based on this statement, it is clear that the use of the spaces is treated as for nonseparated uses, without separate fire areas.

Interestingly enough, I will grant you that a strict reading of the _"Fire Area"_ definition, which refers to the term _"Exterior Wall"_ as defined in the code, which is found in Chapter 14, does not ever send us back to 705.  Hmmm.


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## kilitact (Nov 14, 2012)

Section 707.4, exception does address your concern in regards to stairs, exit enclosures etc. Perhaps the section should have been written diffrent, but I'll hang my hat on it.


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## Builder Bob (Nov 15, 2012)

kilitact said:
			
		

> If the storage area (S-1) exceeds 12,000 sq ft than it would have to be sprinkled or separated into smaller fire areas (less than 12,000 sq ft). This would take you to the requirements for fire areas i.e exterior walls etc. If the two buildings were separated by 78 feet would you require fire barrier construction in place of the exterior wall? Do you consider the exterior wall has an interior wall?


If the designer designated this to be in accordance with 503.2.1, if that is the case, then the aggregate building would have to meet the provisions of the code as stated by this last sentence of the code.


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## kilitact (Nov 15, 2012)

Builder Bob said:
			
		

> If the designer designated this to be in accordance with 503.2.1, if that is the case, then the aggregate building would have to meet the provisions of the code as stated by this last sentence of the code.


The last sentence states that the provisions of this code applicable to the aggregate building shall be applicable to each building.


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## Builder Bob (Nov 15, 2012)

code "The provisions of this code applicable to the aggregate building shall be applicable to each building. "  The provisions of this code applicable to the aggregate building (i.e sprinkler requirement for example) shall me applicable to each building.......

In other words, if it would be required for the footprint of the newly combined aggregate building, it (the code provisions) would be required for each building.   The only thing that 503.2.1 does in reality, is to allow you to remove fire protection ratings for exposure for multiple buildings if they could have been built as one building.


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## kilitact (Nov 16, 2012)

Builder Bob said:
			
		

> code "The provisions of this code applicable to the aggregate building shall be applicable to each building. "  The provisions of this code applicable to the aggregate building (i.e sprinkler requirement for example) shall me applicable to each building.......In other words, if it would be required for the footprint of the newly combined aggregate building, it (the code provisions) would be required for each building.   The only thing that 503.2.1 does in reality, is to allow you to remove fire protection ratings for exposure for multiple buildings if they could have been built as one building.


And if each building had exterior walls that could defined a fire area.


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## globe trekker (Nov 16, 2012)

Which way is the "more restrictive" in this application?

.


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## Builder Bob (Nov 26, 2012)

kilitact - read section 102.1 ------- The definitions of a fire area are a general requirement,  the consolidation of all buildings into one common aggregate building is specific..... where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.

( The issue isn't about the most restrictive as the purpose of this code section is to allow you to build multiple buildings on the same lot as if it was one building.


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## Builder Bob (Nov 26, 2012)




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## kilitact (Nov 28, 2012)

Builder Bob said:
			
		

> kilitact - read section 102.1 ------- The definitions of a fire area are a general requirement,  the consolidation of all buildings into one common aggregate building is specific..... where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.  ( The issue isn't about the most restrictive as the purpose of this code section is to allow you to build multiple buildings on the same lot as if it was one building.


The definition of fire area is specific to defining  fire area design requirements and the code sections to go to. Chapter 9 also has specific language has to when and where they are required, nothing general about it.


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## jpowell (Jan 31, 2013)

Hi guys, I haven't posted much, but have been lurking.

To the original question, I believe the designer has a choice to either consider both new & existing bldgs as one building, or to have the new bldg assume a fire distance and rate the exterior walls accordingly.  Either way there will be different consequences for how the code is applied.

Regarding the sidebar discussion on multiple buildings on one lot:

I agree with Builder Bob here.  The "two or more buildings on one lot" are to be considered one building.  I'll break it down how I follow it in the code.  Under 705.3 it is made clear:

Chapter 7 - Fire and Smoke Protection Features

SECTION 705 EXTERIOR WALLS

705.1 General. Exterior walls shall comply with this section.

705.3 Buildings on the same lot. For the purposes of determining the required wall and opening protection and roof-covering requirements, buildings on the same lot shall be assumed to have an imaginary line between them.

Where a new building is to be erected on the same lot as an existing building, the location of the assumed imaginary line with relation to the existing building shall be such that the exterior wall and opening protection of the existing building meet the criteria as set forth in Sections 705.5 and 705.8.

*Exception: Two or more buildings on the same lot shall either be regulated as separate buildings or shall 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. Where the buildings contain different occupancy groups or are of different types of construction, the area shall be that allowed for the most restrictive occupancy or construction.*

This exception is specific to exterior walls and opening protection within those walls.  If you have assumed these portions as one building, then there would not be exterior wall protection between "itself", and there would be no imaginary line between them.


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