Unlimited area buildings and separation distances between buildings.

[SprinklerDesigner2]

IBC

I am being told the minimum separation distance between two buildings is 31' but I don't see how this is arrived at given the following:

Buildings are manufactured steel type with 8" bent metal purlins, rigid metal frames and insulated metal roof decks. Eave heights are 24'-0" with peaks at 33'-4 1/2". Steel is not protected.... pretty much your standard bent metal purlin buildings.

Buildings are all sprinkled using ESFR systems. k=16.8 pendent discharging at 52 psi. Obviously buildings are used for storage of a wide variety of Class I through Class IV commodities and even some non-expanded plastics.

All the buildings are owned by a single owner who leases out the complex to a variety of different renters.

I can understand separation distances between buildings having different owners but on a single property?

As I am not the building professional I don't need to be able to answer this but I would like to know just for myself.

 

[cdafd]

Are you asking about an existing condition

Or if someone was going to build new?

 

[SprinklerDesigner2]

cdafd,

All new construction.

All same owner on single piece of property with multiple tenants. Distribution and storage centers so everything is ESFR.

Currently there's 60' separation between buildings but what I want to know is per IBC what is the minimum distance between buildings? Being fully sprinkled is there any minimum distance?

 

[SprinklerDesigner2]

Street View

 

[stookeyfpe]

For the buildings on the same property the separation distance is the same: 60 feet. The separation distance in conjunction with an automatic sprinkler system complying with IBC Section 903.3.1.1 is how they obtained the Unlimited Area status. I am assuming this is in Georgia, which adopts the IBC. I'm not sure of which edition they have adopted but my statements are based on the 2009 edition. See IBC Section 507.3.

If these buildings were constructed to the 2009 edition, they could reduce the distance to 40 feet if they applied the reduced space provision in 2009 IBC Section 507.5. However, this provision has some significant construction implications, especially in a pre-engineered "butler" building. IBC Section 507.3 is a new provision in the 2009 edition so if the buildings were constructed to an older edition of the IBC, that option is not available to them unless the building official authorizes its application.

 

[SprinklerDesigner2]

Stookey,

I think my problem is I am looking for a rationale for the 60' separation when one doesn't exist.

I have two buildings of 40,000 sq. ft. each measuring 200x200 that are separated by a minimum of 60'. Being two buildings I must have that 60' separation, assuming no rated exterior walls, but if I filled the 60' with building, effectively creating a 460'x200' building having 92,000 sq. ft., everything is fine?

 

[cdafd]

I think it is just a number in the code book,

just like some of the numbers in nfpa 13, not based on testing just a compromise in making the code.

Now scott may give the real reason.

 

[stookeyfpe]

SD2:

You lost me. Are you saying that your client want to increase the area of the building and by design, eliminate the 60 foot dimension on one side of the building? Because if that is done, the building is no longer Unlimted Area per the IBC. (SCENARIO A)

Or is the scenario where you take the 60 foot of open space, and fill it in with a building. In this scenario, the land owner has sufficent property still have 60 feet on all sides. In this scenario, that is perfectly legal because the building is sprinklered per IFC Section 903.1.1.1. However, ensure that no plat lines or easements are being violated. (SCENARIO B).

Or is the scenario where you have two buildings parallel to each other, each constructed as Unlimited Area buildings. The owner fills in the space by construction and takes two unlimited area buildings and make one building (SCENARIO C). Still legal, provided you have 60 feet on all sides.

I didn't bring up change of occupancy because I am assuming we're dealing with storage and manufacturing. For now, lets get through the question at hand.