Fence built in frontage area after C. O.

[mtlogcabin]

The term "open space" is used a number of different ways within the codes. However, it specifically allows you to include.

1. The closest interior lot line.

2. The entire width of a street, alley or public way.

3. The exterior face of an adjacent building on the same property.

How many streets, alley or public way, (interstates, freeways) have you seen with fences alongside them for various reasons and various height. I have seen highways with 10 and 12 ft tall concrete sound walls in certain areas.

It is up to the local AHJ for what is or is not allowed within that open space. I would be cautious about being over restrictive with the interpretation.
FYI
Our orange and blue home improvement stores along with Wally world have shipping containers located within the open space requirements or non-combustible products such as rebar, concrete blocks up against the back of the building. The FD is okay as long as they leave an apparatus road access for his equipment.

 

[Yankee Chronicler]

The provisions governing area increases for excess frontage are found in IBC 506.3. The IBC Commentary for 506.3 says:

The allowable area of a building is allowed to be increased where it has a certain amount of frontage on
streets (public ways) or open spaces, since this provides access to the structure by fire service personnel,
a temporary refuge area for occupants as they leave the building in a fire emergency and a reduced exposure
to and from adjacent structures. Sections 506.3.1 through 506.3.3 describe how this increase for frontage
is determined.

IBC 506.3.1 goes into how the allowable increase is computed. From the IBC Commentary on 506.3.1:

This section requires that an open space that is not a public way be on the same lot or dedicated for public
use, and it must have access from a street or an approved fire lane in order to contribute to the frontage
increase.
The requirement that the open space be on the same lot is so that the owner or the jurisdiction can
control the space that is assumed to be open for purposes of the area increase. One cannot encumber a
neighbor’s property with a requirement that the space will always remain unoccupied.
Any part of the perimeter that is not accessible to the fire department by means of a street or fire lane cannot
be considered open for the purposes of this section. For instance, if the back side of a building on a narrow
lot cannot be reached by means of a fire lane on one side of the building (and there is no alley or street at
the back), that portion of the perimeter is not considered open for purposes of frontage increase, even if
there is actual open space exceeding 20 feet (6096 mm) in width. See Commentary Figure 506.3.1(2) as
an illustration of this limitation.

 

[steveray]

I can't find the word "Yard" in the Frontage Increase section. But I only have the 2018 IBC and it might be in other versions. There is no definition of "Frontage" or "Open Space" in the 2018 too. So, I guess it up to everyone's interpretation.

As it should be.....

 

[Yikes]

The provisions governing area increases for excess frontage are found in IBC 506.3. The IBC Commentary for 506.3 says:

IBC 506.3.1 goes into how the allowable increase is computed. From the IBC Commentary on 506.3.1:

That's interesting. The open yard increase has been in the code for decades, and older versions of the ICBO Handbook said that better fire department access was a benefit, and access is a "good idea", but NOT a code requirement. I wonder when the commentary changed? And if it is critical to provide an apparatus access road in the yard, and not merely "have access from" a street/fire lane to the edge of the yard, why didn't the code say this explicitly?

Here's an excerpt from the 1995 IBC Handbook:

 

[Yankee Chronicler]

That's interesting. The open yard increase has been in the code for decades, and older versions of the ICBO Handbook said that better fire department access was a benefit, and access is a "good idea", but NOT a code requirement. I wonder when the commentary changed? And if it is critical to provide an apparatus access road in the yard, and not merely "have access from" a street/fire lane to the edge of the yard, why didn't the code say this explicitly?

Here's an excerpt from the 1995 IBC Handbook:

I assume that's a typo, since there was no 1995 IBC.

I'm in the northeast, so pre-ICC we used the BOCA codes. I have all our old codes, but no commentaries or handbooks. All I can say is as far back as 1972, when I graduated from architecture school and started working full-time as an architect, it was understood that in order to qualify for an increase in allowable tabular area, the open space had to be suitable for firefighting operations. For example, if the back of a building had 100 feet to the rear property line but two feet away from the building it started to slope down at a ridiculous angle -- it couldn't be counted as excess open perimeter for purposes of area increases. The same applied if it was thickly forested and the owner declined to cut down trees and grade the site for a sufficient distance away from the building to allow firefighting operations.

My old BOCA codes are in storage in the dungeon, but I'm fairly certain that in BOCA the open space and access thereto were a requirement, not just "a good idea."

 

[Yikes]

I assume that's a typo, since there was no 1995 IBC.

To clarify, it was a 1995 Handbook, covering the 1994 UBC.

 

[Yikes]

For example, if the back of a building had 100 feet to the rear property line but two feet away from the building it started to slope down at a ridiculous angle -- it couldn't be counted as excess open perimeter for purposes of area increases. The same applied if it was thickly forested and the owner declined to cut down trees and grade the site for a sufficient distance away from the building to allow firefighting operations.

From the same 1995 Handbook, here they think that a flood control channel would make a reasonable yard - - clearly not worried about fire vehicle access:

 

[Yankee Chronicler]

In BOCA days of old, if we had any question regarding the suitability of an open space we would consult the fire marshal and fire chief. If they were willing to accept it as suitable for fire department access (which was the intent of the provision), we would feel comfortable using it.

More recently, under a previous edition of the IBC, a museum wanted to build an addition and needed to use the excess frontage provision to be able to meet the area limitations. The rear of the building fronted ("reared"?) on an interstate highway ramp, which is certainly a public way. The fire department said there was no way they were going to stage their vehicles on a highway ramp to fight a fire in an adjacent building. No increase allowed.

 

[Yankee Chronicler]

I dug up a copy of an old BOCA Basic Building Code at work. Here's the way BOCA presented the area increase for excess frontage: