Can frontage increase be applied to multiple fire areas?

[Ryan Schultz]

Let's say you have (1) building made up of (2) fire areas--as illustrated below--all on the same property.

When determining the allowable area of the entire building, can the frontage increases alloted by the 60ft setbacks apply to both fire areas, or would it only apply to Fire Area B?

 

[classicT]

Well, seeing as frontage increases are applied to the allowable building area, it would apply to the entire building.

No such thing as an area increase for a fire area.

In the proposed image, the building does not have 25% of its perimeter on a public way or open space.

506.3.1 Minimum Percentage of Perimeter
To qualify for an area factor increase based on frontage, a building shall have not less than 25 percent of its perimeter on a public way or open space. Such open space shall be either on the same lot or dedicated for public use and shall be accessed from a street or approved fire lane.​

 

[RLGA]

The allowable area is applied to each separate building; thus, the frontage increase is based on each separate building. When a fire wall is used, the frontage where the building connects is zero for the length of the fire wall.

If Building A is a separate building, then no frontage increase would be permitted since not more than 25% of the building perimeter is on a public way or open space leading to a public way having a width of at least 20 feet.

 

[classicT]

Ahh...good eye Ron. I missed the fire wall and was responding as if the whole thing was one building, not two.

Ryan, is it actually a fire wall, and not a fire barrier? Structural independence to allow collapse on either side?

 

[Ryan Schultz]

Thanks Ron & Ty

Ryan, is it actually a fire wall, and not a fire barrier? Structural independence to allow collapse on either side?

That's t.b.d.--assessing whether existing walls are structural independent can sometime be hard to determine in the field. Any pointers, other than selective demo, to determine if the wall is structural independent?

The particular walls that i'm looking at are CMU walls that divide large chunks of Type 2B warehouse space (60,000sf, 50,000sf, and 10,000sf) with steel rolldown doors--one would assume these are firewalls.

 

[Paul Sweet]

Are the structural systems on each side independent? If the "fire wall" is load bearing then it has to be a double wall with a separate wythe supporting each side, or there has to be special detailing to allow the framing on one side to pull away when it sags during a fire without pulling the wall over with it..