Frontage

[Sifu]

Large building, separated into 3 by fire walls. In the snippet, the yellow highlight is one building, and the smaller non-highlighted one is another. Frontage is being taken for the exterior walls adjacent to the area that contains the pool. Given the snippet, would you consider the space around the pool as available frontage?

It is an "open space", on the same lot. Access is provided at the lower area from the street through the pool barrier fence (yellow). Does that answer my own question? I always get a little heart-burn over what constitutes frontage perimeter.

 

[steveray]

Is it accessed from a fire lane?

506.3.1​

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.

 

[walker.t]

I always get a little heart-burn over what constitutes frontage perimeter

2018 IBC Illustrated Handbook commentary on 506.3 Frontage Increase (partial quote, emphasis added)
Although the term open space is not specifically defined in the IBC, the definition of a yard is an open space unobstructed from the ground to the sky that is located on the lot on which the building is situated. It is logical that this definition is consistent with the intended description of open space. This definition seems to preclude the storage of pallets, lumber, manufactured good, home improvement materials, or any other objects that similar obstruct the open space.

Do you have 20’ between the pool and the walls of the building surrounding the pool? Also, not sure what is in the space between the pool and the building but it looks so cluttered with stuff (maybe tables and umbrellas) that I don’t think it meets the intent of “open” for the sake of access for fire fighters even if you provided the required fire lane through the gap between the buildings.

 

[steveray]

I say nay nay....

 

[Sifu]

Accessed from a street located plan south. Hard to make out but you can just see the bike riding figure and arrow which is adjacent to the street. A hose dragger could get in at the fence shown on plan south, but that is it. Also looking at the pool. If the frontage is permitted, I need to determine the smallest frontage distance. The pool edge is a little less than 20' from a section of wall. So that couldn't be counted unless standing in the pool counts, and most of the walls are less than 25', so the 20' to 25' row in the table would be applied. Unless standing in the pool counts. Hard for me to imagine standing in the pool counts as providing fire-fighter access, then again, your in WATER.

So the two issues are whether frontage is allowed at all for these enclosing walls with just the narrow opening at plan south to the street, and if allowed, how/what to measure to for the 20' min.

 

[Sifu]

Do you have 20’ between the pool and the walls of the building surrounding the pool? Also, not sure what is in the space between the pool and the building but it looks so cluttered with stuff (maybe tables and umbrellas) that I don’t think it meets the intent of “open” for the sake of access for fire fighters even if you provided the required fire lane through the gap between the buildings.

Based on scaling, a small section is a few inches shy of of the pool edge, the rest is around 22 to 26'. First real test of the new frontage table for me. Old code provided a weighted average of distance. Doesn't appear to be the case in the table as it seems to say use the smallest measurement and plug it into the table. Do I have that right?

 

[Yankee Chronicler]

The basis for the allowable increase is that the "excess" open space is accessible to and usable by fire fighters to fight fires. They can't stage ladders or run hose streams for a swimming pool, so that frontage IMHO can't be counted.

I have argued that a proposed building surrounded on three sides by heavily forested land cannot be used to claim an area increase. The property was large enough, but stands of mature trees precluded any meaningful access to most of the "excess" perimeter.

Also, in the plan you posted there's a fence between the wing or building at lower left and the pool (see the note with call-out arrows at extreme lower left). If it's fenced, it's not open.

 

[Sifu]

While I agree that "open" is subjective, I have also been advised that trees and fences can be included in frontage. The fence shown here has a gate, though not sure that would slow down the firefighters. The pool area is full of tables, chairs, umbrellas, planters, and as you point out, water. The archiect is using the pool area in his calculation. He is using 30' which would put you in the pool on the entire peremiter of the pool. He is the using the 30' row from the table, but I suppose he could be using that because he is including the surface of the water.

So same two issues...is it "open" enough for fire-fighters, and if so, what can be in/obstructing it?

FWIW, I think the "open" part is too subjective. A hose can be dragged in there. The obstructions are also subjective, fire-fighters can navigate and move chairs and umbrellas, but while I have great respect for fire-fighters, I don't THINK they can walk on water.

I THINK the area could be used as frontage, but I also THINK the open width would be limited to the pool edge. I also THINK the 2021 IBC did away with the weighted average of width an now applies the narrowest point to the entire frontage.

Having dinner with a local Lieutenant tonight, I'll be interested in his thoughts.

 

[Yankee Chronicler]

While I agree that "open" is subjective, I have also been advised that trees and fences can be included in frontage. The fence shown here has a gate, though not sure that would slow down the firefighters. The pool area is full of tables, chairs, umbrellas, planters, and as you point out, water. The archiect is using the pool area in his calculation. He is using 30' which would put you in the pool on the entire peremiter of the pool. He is the using the 30' row from the table, but I suppose he could be using that because he is including the surface of the water.

So same two issues...is it "open" enough for fire-fighters, and if so, what can be in/obstructing it?

Ask your fire marshal to ask his fire chief.

Several years ago I consulted to an architect who was designing an addition to a museum. He wanted to get an area increase, and we had one of the long sides of the parcel fronting on a highway (I-95) on ramp. On paper, it met all the requirements. It was paved, it was wide open, and as a state highway the road was maintained in all weather.

The fire chief said there was no way he was going to shut down an interstate highway ramp to fight a fire, so he told the building official that under no circumstances should he consider that as excess open perimeter.

From the 2021 IBC Commentary:

While I agree that "open" is subjective, I have also been advised that trees and fences can be included in frontage.

What was the source of this advice? In my days as an architect I dealt with a lot of fire departments when discussing area increases. That's where I got the notion that the intent isn't just "not a building" bot open meaning "Open enough for firefighters to do their thing." There's no way I would allow, for example, a forest. A site with one or two scattered specimen trees, that's negotiable. Raw forest is not open enough for firefighting operations.

Had another one where the back of a proposed addition to a factory backed up to a fairly steep incline, with some rock outcroppings poking out of the hillside. This was another case where the fire department said, "No just 'No' but "Hell no!' " They were very serious that if the space surrounding the building wasn't open, flat, and firm enough for men (in turnout gear), hoses, and ladders to get in and fight a fire -- they were opposed to allowing an area increase. In this case, the fire chief determined that the hill was too steep and uneven for his personnel to safely get back there, so he vetoed the increase.

An actual swimming pool obviously doesn't count. If portions of the open space was swampy terrain, that probably shouldn't be allowed, either.

 

[Yankee Chronicler]

More from the 2021 IBC Commentary:


IIRC, the rule of thumb is a 100-foot hose line. (I am NOT certain of this.) The Commentary makes it pretty clear that the open space isn't just property that's part of the parcel on a deed or survey map, it's space from which firefighters can actually fight a fire without undue impediments.

 

[walker.t]

as it seems to say use the smallest measurement and plug it into the table. Do I have that right?

Yes, that is correct per 2021 IBC 506.3.2. Kind of seems a little unfair because you could have 30’ on three sides and 21’ on one side and you’d have to use the 20’ to 25’ column in Table 506.3.3 for your minimum frontage distance. Table 506.3.3 does say that interpolation is permitted, I’ve been wanting to make a chart or a spreadsheet to do that calculation but haven’t had the time.

I have argued that a proposed building surrounded on three sides by heavily forested land cannot be used to claim an area increase.

There’s no argument in my opinion, you’re absolutely correct.

2018 IBC Illustrated Handbook commentary on 506.3 Frontage Increase (partial quote)
…the frontage increase is based on the ability of the fire personnel to physically approach the building’s exterior under reasonable conditions. For example, where the space adjacent to the building is heavily forested or steeply sloped, the frontage increase…is not permitted. The presence of a lake or similar water feature next to a building would also prohibit an area increase.

 

[steveray]

The intent is a safe space to fight the fire from….I don’t think that works…

 

[Yankee Chronicler]

The intent also seems to be that each portion or side of the open space is to be considered separately for being accessible from a street or posted fire lane. Again from the 2021 IBC Commentary:



Comparing this to the plan being discussed, the rear yard with the swimming pool would be at the top (replace "trees" with "pool"), and the side yard at the right would be the space between the two wings of the building. The "side yard" can be accessed from the street (except for the fence), but there's no posted fire lane providing firefighter access to the "rear" yard -- where the pool is located.

 

[Sifu]

The way I am interpreting the frontage limitations from the 2021:
The street at plan south provides the access point, personnel can access through the gap to the courtyard and take frontage for the space directly off the access to the right (in green) but once they turn the corner the access is from the street is no longer direct so the two sides (in red) are no longer available for frontage. Plus the right side is < 20'. From the access point to the left (in yellow) there is a gap of 12'5" total, and 3' from the fence so they couldn't use this as a continuance of the access route to get to the 26'11" space from the left side either.

So these statements are what I think are true based on the code and commentary:
1) From a street you get to make your way to one side of the building and use that as open frontage if it is 20' min. but you can't access the next side of the building since access is no longer provided by the street (you can't turn the corner).
2) You can't use a space that has a 20' min. distance from the building if the only way to get to it is by traveling through spaces that do not have the min. 20' distance.
3) If you can't physically use (stand on) a 20' wide piece of ground that A) provides access to the structure by fire service personnel or B) provide temporary refuge for building occupants then the space can't be used as open perimeter.

However, notice the gap distance between the building and the corner of the adjacent building. It is less than 20'. Does this negate everything? Code says the measurement is at a right angle to the building, so I'm not sure if this can be the limiting distance.

No matter how one interprets what can or can't be in the open space the only way to take all the open perimeter at 30' they would have to count the surface of the water as open space and get to all of the spaces through a gap that is less than 20' wide.



This is their frontage calculation:

 

[steveray]

If it was a doughnut you wouldn’t use the courtyard as perimeter, but you would not count it either…

 

[Sifu]

Now I want a doughnut!

I have requested a technical opinion about this stuff. I asked about the surface of the water. I feel silly asking, but since the DP is proposing it I would like something more than my own opinion. I asked about the effective gap, measured at the angle. I asked about no longer using a weighted average for frontage width.

Looking at the allowable area calculation and ratio sum for a 4 story building I am afraid this could be a significant issue since they are close to 3 using the allowable area with full frontage.

 

[Tim Mailloux]

If it was a doughnut you wouldn’t use the courtyard as perimeter, but you would not count it either…

a little off topic, but if it was a doughnut why wouldn't you could the inside of the doughnut as part of the perimeter?

To calculate the "perimeter" of a donut (an annulus), you need to sum the circumferences of its outer and inner circular edges. You can do this by finding the outer radius (R) and the inner radius (r), calculating each circumference using the formula C = 2πr (or C = πd if you have the diameter), and then adding them together: Outer Circumference + Inner Circumference = Total Perimeter

 

[Sifu]

Now I am getting a little more skeptical. This is an an analysis of a 2nd building. It wouldn't need frontage to make allowable area, but the calculation they use takes it as NS x 1.

 

[Tim Mailloux]

Do these buildings have an NFPA-13 or NFPA-13R sprinkler system? There are some difference in the math for calculating Allowable Building area depending on the type of system.

 

[Sifu]

Full 13.

 

[Yankee Chronicler]

The way I am interpreting the frontage limitations from the 2021:
The street at plan south provides the access point, personnel can access through the gap to the courtyard and take frontage for the space directly off the access to the right (in green) but once they turn the corner the access is from the street is no longer direct so the two sides (in red) are no longer available for frontage. Plus the right side is < 20'. From the access point to the left (in yellow) there is a gap of 12'5" total, and 3' from the fence so they couldn't use this as a continuance of the access route to get to the 26'11" space from the left side either.

So these statements are what I think are true based on the code and commentary:
1) From a street you get to make your way to one side of the building and use that as open frontage if it is 20' min. but you can't access the next side of the building since access is no longer provided by the street (you can't turn the corner).
2) You can't use a space that has a 20' min. distance from the building if the only way to get to it is by traveling through spaces that do not have the min. 20' distance.
3) If you can't physically use (stand on) a 20' wide piece of ground that A) provides access to the structure by fire service personnel or B) provide temporary refuge for building occupants then the space can't be used as open perimeter.

However, notice the gap distance between the building and the corner of the adjacent building. It is less than 20'. Does this negate everything? Code says the measurement is at a right angle to the building, so I'm not sure if this can be the limiting distance.

No matter how one interprets what can or can't be in the open space the only way to take all the open perimeter at 30' they would have to count the surface of the water as open space and get to all of the spaces through a gap that is less than 20' wide.

Looking at the sample diagrams from the IBC Commentary, I think the application of those principles to this project would result in less space being allowed for open perimeter than your mark-up. The portion of your colored lines that I changed from yellow to red is no different from the rear yard in the Commentary figures. It's not accessed directly by a street or a posted fire lane, so it can't be counted. What this project has is like figure 506.3.1(2), not like Figure 506.3.1(3).

 

[Sifu]

Looking at the sample diagrams from the IBC Commentary, I think the application of those principles to this project would result in less space being allowed for open perimeter than your mark-up. The portion of your colored lines that I changed from yellow to red is no different from the rear yard in the Commentary figures. It's not accessed directly by a street or a posted fire lane, so it can't be counted. What this project has is like figure 506.3.1(2), not like Figure 506.3.1(3).

View attachment 16737

Yes, I was skeptical of even this space since it is not direct and there is a corner to navigate. So maybe they get nothing.

 

[walker.t]

the new frontage table

So that means you’re using 2021 IBC, but the applicant has submitted a plan using the 2018 IBC method - are you in a transition period that allows the designer to comply with either code? Table 506.3.3 says interpolation is permitted, it doesn’t say calculation per the 2018 IBC method is permitted.

However, notice the gap distance between the building and the corner of the adjacent building. It is less than 20'. Does this negate everything?

I think it precludes anything on the far side of the reduced width from being considered frontage:

1. 2021 IBC 506.3.1 requires perimeter to be accessed from a street or fire line. Implied in my opinion is that the entire access path be open space per 506.3.2.
2. 2021 IBC 506.3.2 says minimum width of the open space is 20’.

but the calculation they use takes it as NS x 1.

Nice catch, shows you’re doing a thorough review.

 

[steveray]

a little off topic, but if it was a doughnut why wouldn't you could the inside of the doughnut as part of the perimeter?

Because the interior perimeter of the doughnut is not available for firefighter operations..Because that is the intent…

Read it like this a little…

506.3.1​

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.

If the space doesn’t have direct access from a street or fire lane it doesn’t count…IMO