Anybody done a variance for an unlimited area building, with another building within the 60' open space requirement?

[Morphdesigns]

I am working on a large unlimited area building. In Wisconsin, we are using IBC 2015. Per IBC 507, you need a 60' clear open space on all 4 sides. This building is a 1-story and sprinklered. Per IBC 507.2.1, you are allowed reduced open space, down to 40', if you build a 3-hr wall on the unlimited area building, on the side that is face the reduced open space, as long as it does not go less than 40'.

I have a another building on this site, that is at a 30d angle to my unlimited area building. This building is limited in area, is unoccupied, and is not sprinklered. A corner of this building goes into this required 60' clear space by 8'. So I have 16' of wall on one sidewall and 4' of the other endwall, of this second building within this 60' space. I know that one option is putting a masonry 3-hr wall on my unlimited area building, that is facing this 2nd building.

But I am looking into other options. And hoping that other people might have submitted to their local or state AHJ, as a variance to this code standard. I talked to the sprinkler contractor on the job, and he thought that he did a job that they added rows of exterior sprinkler heads, at 10' oc vertically, facing a tank farm, but after looking into it, it was actually a requirement of FM global to do that, and not because of IBC section 507.2.1.

I was hoping that somebody has done something similar and created a variance to go around this? In Wisconsin, we have a variance process that gives alternate opinions to do instead of following the code. If the description is adequate and the state reviewer discusses this with others, and agrees that this alternate option still follows the intent of the code, it will pass. As I have only worked here, I am not sure if other AHJ's have options to do this.

Thanks for the help.

 

[classicT]

The problem that I foresee, is the 60-ft yard is to provide area for firefighters to have access around the building while maintaining safe distance. Typically, firefighters want to set up at the corners of buildings, where the risk of a wall collapsing outward and on or towards firefighters and their equipment is lower. However, with buildings of significant size, they need to set up along the side to be able to conduct their firefighting operations. Therefore, the greater yard width is necessary for them to conduct their operations safely. They need to be out of the collapse zone, have enough room to set up, and still maintain access for other trucks to move around the building.

As an example, if you have building height of 20', the collapse zone is 1.5x the height, so 30'. A ladder truck with outriggers can be 20' wide, leaving only 10' to get around that engine where a 60' yard is provided.

So, what I'd suggest is that you start talking with the fire marshal, because while this issue appears to be established in the building code, the intent of the code is to provide safe area for firefighters to combat a fire.

 

[RLGA]

If the outer building has 60-foot open spaces around the perimeter that is not adjacent to the unlimited area building, then that building can be considered a portion of the unlimited area, provided the outer building's construction type, sprinklered condition, and occupancy group(s) are permitted for the unlimited area building requirements.

Since the outer building is nonsprinklered, this is probably unlikely.

Also, the 3-hour wall applies only to the portion of the exterior wall that has a reduced width. Thus, the entire wall on that side is not required to be 3-hour--just the portion that is reduced. So, you would only need about 16-1/2 feet of 3-hour exterior wall construction.