Flat roof setbacks in California

[fraser]

So I've asked a similar question before, but now after finally reviewing the 2022 NFPA and IFC codes, I think I have this right. I have a mixed roof, one part flat, one part pitched. On the flat part, if I read the codes right, there are NO setback requirements for flat roofs, right??? I would put in a 36" pathway to get to the pitched roof, but that is it for requirements, and even that seems more than the code requires. For the pitched roof, if I am covering less than 33% of the roof, and its not the side facing the street, then an 18" setback from the horizontal ridge is the only requirement. There does need to be 3 feet on either side as well (for fire ladders) I was told by a building inspector, but that doesn't seem to be exactly right (seems only 1 36" area is needed). If this is correct, then those houses with flat roofs can accommodate a lot more solar panels then what most solar installers are suggesting. Any comments or thoughts would be welcomed, especially anyone who has installed on flat roofs.


Here is the IFC code (Flat roofs are actually excepted from these requirements though):

1205.2.1Solar photovoltaic (PV) systems for Group R-3 buildings.


Solar photovoltaic (PV) systems for Group R-3 buildings shall comply with Sections 1205.2.1.1 through 1205.2.3.

Exceptions:

1. These requirements shall not apply to structures designed and constructed in accordance with the International Residential Code.
2. These requirements shall not apply to roofs with slopes of 2 units vertical in 12 units horizontal (16.7-percent slope) or less.

1205.2.1.1Pathways to ridge.


Not fewer than two 36-inch-wide (914 mm) pathways on separate roof planes, from lowest roof edge to ridge, shall be provided on all buildings. Not fewer than one pathway shall be provided on the street or driveway side of the roof. For each roof plane with a photovoltaic array, not fewer than one 36-inch-wide (914 mm) pathway from lowest roof edge to ridge shall be provided on the same roof plane as the photovoltaic array, on an adjacent roof plane or straddling the same and adjacent roof planes.

[Calsun]

There is an overriding requirement to have room for a fire fighter to be able to move around on the roof in the event of a home fire. I had to devote 25% of my flat roof space for this requirement. The local fire department had to sign off on my installation before the building department would do so and this was a requirement of the local utility company.

A separate problem is attachment of panels to insure they do not end up on the ground or hit someone on the ground in the event of an earthquake and that can make a parapet mandatory in some situations.

[fraser]

There is an overriding requirement to have room for a fire fighter to be able to move around on the roof in the event of a home fire. I had to devote 25% of my flat roof space for this requirement. The local fire department had to sign off on my installation before the building department would do so and this was a requirement of the local utility company.

A separate problem is attachment of panels to insure they do not end up on the ground or hit someone on the ground in the event of an earthquake and that can make a parapet mandatory in some situations.

Did you have to visit the fire department or just submit at the permitting office to get this approved? Did they have actual rules, or did they just say "we need more space for firefighters?". I can make a 36 inch path on 2 edges, which is more than what they require on pitched roofs, so I'd be surprised that they would require more on a flat roof that is supposedly exempted from the rules on a pitched roof.

Obviously, I am trying to maximize the size pre NEM 3.0, so setbacks will have a great impact. I've submitted my questions by email but it's been a week with no response. Same for the voicemails. I guess I have to camp in front of the SF fire plan review help desk at 730am. I checked at 9am and the wait was 3.5 hours. Any other suggestions?

[fraser]

Sooo, I finally got an email back from permit dept. They want a 3foot perimeter. When I asked where that was in the code, they said there is no code, that's just what the fire marshal wants. Hmmm. Sounds fishy... No code???

[Mike 134]

Sooo, I finally got an email back from permit dept. They want a 3foot perimeter. When I asked where that was in the code, they said there is no code, that's just what the fire marshal wants. Hmmm. Sounds fishy... No code???

What he says goes. He is the "AHJ" = Authority Having Jurisdiction. Follow his requirements now or change it later.

[J.P.M.]

What he says goes. He is the "AHJ" = Authority Having Jurisdiction. Follow his requirements now or change it later.

In agreement with Mike: Two rules when dealing with any AHJ or inspection authority:

1.) The inspector is always right.
2.) If the inspector is wrong, see rule # 1.

For dealing with national or international codes and enforcement bodies there are procedures and protocols for dealing with interpretations and disputes, but a homeowner at the local level rarely has the knowledge, political heft, money or time to go through the process,
So, for practical reality, you're back to rule #1.

[fraser]

In agreement with Mike: Two rules when dealing with any AHJ or inspection authority:

1.) The inspector is always right.
2.) If the inspector is wrong, see rule # 1.

For dealing with national or international codes and enforcement bodies there are procedures and protocols for dealing with interpretations and disputes, but a homeowner at the local level rarely has the knowledge, political heft, money or time to go through the process,
So, for practical reality, you're back to rule #1.

So I'm not sure if you both are conflating the 2 agencies (the building dpmt and the fire dept), or are they really considered as one for the AHJ? The building inspector says he does what the fire dept says to do. The fire dept, may or may not be using the most up to date rules for this. In SF, the fire code now supposedly follows what California says is code, which follows the IFC. So, it if possible, even likely, that the fire dept msg was an old message, since it didn't conform to current code, and the building dept just never updated it. Only way to find out is to ask the fire dept. I won't bother for this single installation, but I was hoping to help others with their flat roof installations going forward. Namely, I'm looking at max $1.6/kw on a flat roof, where the lowest quote I got was just under $3/kw. There's a lot of "fluff" in that $3/kw. I'd like to be able to maximize the usage of solar on flat roofs. Anyway, I was asking an architect friend of mine who advises one city on its building code requirements, and he thought this was quite irregular, but also said, just do what is easiest.

[littleharbor2]

So I'm not sure if you both are conflating the 2 agencies (the building dpmt and the fire dept), or are they really considered as one for the AHJ? The building inspector says he does what the fire dept says to do. The fire dept, may or may not be using the most up to date rules for this. In SF, the fire code now supposedly follows what California says is code, which follows the IFC. So, it if possible, even likely, that the fire dept msg was an old message, since it didn't conform to current code, and the building dept just never updated it. Only way to find out is to ask the fire dept. I won't bother for this single installation, but I was hoping to help others with their flat roof installations going forward. Namely, I'm looking at max $1.6/kw on a flat roof, where the lowest quote I got was just under $3/kw. There's a lot of "fluff" in that $3/kw. I'd like to be able to maximize the usage of solar on flat roofs. Anyway, I was asking an architect friend of mine who advises one city on its building code requirements, and he thought this was quite irregular, but also said, just do what is easiest.

The AHJ may be the person/agency who enforces their rules but have no doubt, if the Fire Marshall says he wants x amount of setback on roof mounted PV, THAT'S what will be enforced by the AHJ

[J.P.M.]

So I'm not sure if you both are conflating the 2 agencies (the building dpmt and the fire dept), or are they really considered as one for the AHJ? The building inspector says he does what the fire dept says to do. The fire dept, may or may not be using the most up to date rules for this. In SF, the fire code now supposedly follows what California says is code, which follows the IFC. So, it if possible, even likely, that the fire dept msg was an old message, since it didn't conform to current code, and the building dept just never updated it. Only way to find out is to ask the fire dept. I won't bother for this single installation, but I was hoping to help others with their flat roof installations going forward. Namely, I'm looking at max $1.6/kw on a flat roof, where the lowest quote I got was just under $3/kw. There's a lot of "fluff" in that $3/kw. I'd like to be able to maximize the usage of solar on flat roofs. Anyway, I was asking an architect friend of mine who advises one city on its building code requirements, and he thought this was quite irregular, but also said, just do what is easiest.

I don't believe I am.
I spent some parts of an engineering career dealing with overlapping inspection authorities and finding paths through what were/are sometimes overlapping and competing bureaucracies and egos.
I also got to participate in a couple of ASME Pressure Vessel subcommittees that, among other duties, resolve issues that arose in code interpretations of the Boiler and Pressure Vessel Code that all pressure vessel people live and die with, and what pressure vessel inspectors and the agencies they work for interpret and enforce.

Whether or not the AHJ (apparently the building dept. in this case) is up to date or misinformed or wrong or just plain obstinate makes no difference to you.
You, or more accurately your project, must satisfy their requirements.
Authority Having Jurisdiction mean just that.

While working I often had some resolution in getting most AHJ's (in my case pressure vessels inspectors employed by insurance companies) to see my side of things by first looking at the issue from the inspector's side of the issue and thinking like the other guy who I came to find out really does want to do the right thing most of the time but needs to be given an easy path to see my solution (s) as part of the best one.
In dealing with ispection folks and their agencies I always made sure I had my information dead nuts accurate and complete and my ducks lined up if for no other reason than I learned to assume that most inspectors knew their stuff probably and at least as well and as completely as I did and wasting their time trying to mansplain things to them usually just pissed them, which didn't help me to get to my goal(s).
I was never afraid to escalate an issue but did so knowing (partly from experience) that it could backfire.

Take what you want of the above. Scrap the rest.

[fraser]

I don't believe I am.
I spent some parts of an engineering career dealing with overlapping inspection authorities and finding paths through what were/are sometimes overlapping and competing bureaucracies and egos.
I also got to participate in a couple of ASME Pressure Vessel subcommittees that, among other duties, resolve issues that arose in code interpretations of the Boiler and Pressure Vessel Code that all pressure vessel people live and die with, and what pressure vessel inspectors and the agencies they work for interpret and enforce.

Whether or not the AHJ (apparently the building dept. in this case) is up to date or misinformed or wrong or just plain obstinate makes no difference to you.
You, or more accurately your project, must satisfy their requirements.
Authority Having Jurisdiction mean just that.

While working I often had some resolution in getting most AHJ's (in my case pressure vessels inspectors employed by insurance companies) to see my side of things by first looking at the issue from the inspector's side of the issue and thinking like the other guy who I came to find out really does want to do the right thing most of the time but needs to be given an easy path to see my solution (s) as part of the best one.
In dealing with ispection folks and their agencies I always made sure I had my information dead nuts accurate and complete and my ducks lined up if for no other reason than I learned to assume that most inspectors knew their stuff probably and at least as well and as completely as I did and wasting their time trying to mansplain things to them usually just pissed them, which didn't help me to get to my goal(s).
I was never afraid to escalate an issue but did so knowing (partly from experience) that it could backfire.

Take what you want of the above. Scrap the rest.

Yep, path of least resistance for now. I will just make a 36" perimeter around the roof. At least I don't have to put a pathway on the flat part of the roof that is connected to the A frame, so I end up with almost the same number of 540w panels (23 instead of 24), in a slightly different configuration, plus another 7 400w panels on the pitched roof for 15.32kw dc. If I can get my electrician to derate my existing elec panel to 150a, then I don't even have to install a new one.

So, (2) 7.6Kw growatt inverters or (1) 10K and (1) 6kw inverter? Second option is slightly cheaper, despite being larger, but there is simplicity in having 2 of the exact same inverters. Both options fit in the 72a (90a before120rule, 240a-150a). No difference? Looks like I wouldn't be clipping with either option.

And why don't they size inverters to fit the common derating options for elec panels? It's either 175 or 150a, so 240-175=65a or 52a after 120 rule, or 240-150=90a or 72a after 120 rule. Manufacturers should make inverter sizes that exactly match up with the max amps allowed. Why don't they? Am I missing something?

[Mike 134]

And why don't they size inverters to fit the common derating options for elec panels? It's either 175 or 150a, so 240-175=65a or 52a after 120 rule, or 240-150=90a or 72a after 120 rule. Manufacturers should make inverter sizes that exactly match up with the max amps allowed. Why don't they? Am I missing something?

So you're saying make them bigger = more expensive, so they match max amps even if you'll never need the increase in size of the inverter?

[J.P.M.]

Fraser :

A bit off topic but FWIW:
Are you angling (tilting) the panels on the (mostly) horizontal roof section(s) ?
If not - that is, parallel to the (mostly) horizontal roof section(s) and so a (mostly) horizontal panel orientation - and just something to think about, horizontal (or close to it) panel orientations need much more strenuous and much more frequent cleaning than angled (tilted off horizontal) orientations. If not, they wind up being evaporator pans is short order in dry climates and mud pans in climates that are less than dry.
For horizontal (or close to it) panel orientations, leaving access spaces between alternate rows of panels makes life a whole lot easier.

Take what you want of the above. Scrap the rest.

[littleharbor2]

Fraser :

A bit off topic but FWIW:
Are you angling (tilting) the panels on the (mostly) horizontal roof section(s) ?
If not - that is, parallel to the (mostly) horizontal roof section(s) and so a (mostly) horizontal panel orientation - and just something to think about, horizontal (or close to it) panel orientations need much more strenuous and much more frequent cleaning than angled (tilted off horizontal) orientations. If not, they wind up being evaporator pans is short order in dry climates and mud pans in climates that are less than dry.
For horizontal (or close to it) panel orientations, leaving access spaces between alternate rows alternate rows of panels makes life a whole lot easier.

Take what you want of the above. Scrap the rest.

Plus those Evaporator/Mud pans end up leaving hard mineral deposits on the glass that is hard to remove and if scraped you end up risking damage to the Anti-reflective coatings

[fraser]

Every panel will be at least 10 degrees. I am using an east west tilt to minimize inter row spacing. With the 3ft setbacks this is crucial.

[solarix]

I find in my area that the fire officials could care less about solar and over reach the code rules concerning roof access in the name of fire safety. They do not appreciate how much these rules impact the number of solar homeowners that can't do a cost effective system.