California Fire Set Backs from Roof Ridge

[holeydonut]

With all the BS around fire rule changes in NorCal, I guess Sunrun is taking way more time assessing my design before it goes in. A new wrinkle has arisen around the interpretation of California Residential Code (CRC) R324.6.2

My house is designed weird - it's a two story home with a vaulted ceiling that is asymmetrical to the house. So one of my roof lines is shallow, but the Southeast facing roof line is rather steep. And, neither roofline points toward the street. The only way to access my roof with a ground-ladder is to go up the West side of the house and hoof it over to the East side. There is no way to put a ladder on the East side and get to the roof since my neighbor's fence gets in the way.

That means if there's a fire, I think the pathway to the ridge line of the roof is to put a ladder up on the West side and work East. So, I think this means I only needed 18 inches from the roof ridge to the PV array.

Butttt an alternate interpretation of this is that a ladder truck parking on my driveway could directly access the roof on the Southeast side. This means the Southeast roof becomes the access point, and I will now need 36" set back from the ridge. With this interpretation, the upper course of solar panels would need to be mounted in "landscape" mode and I'd lose panels.

I can't tell what is a reasonable interpretation of R324.6.2... isn't 18" sufficient from the ridge even if the access point doesn't face the street?

I'm about at wits end being a PM on my PV + Battery installation ... I feel like if I got some investment together I could start a clean energy company. What do you think @Vines and @wwhitney ?

I've attached two pictures showing a crude mock-up of the issue.
Picture 1 shows the landscape orientation that would give a much fatter pink zone (36" from the ridge)
Picture 2 shows the portrait orientation that I thought I was getting before all this BS around fire codes (18" from the ridge)


One last note: I've intentionally made the solar panels HUUUGGEE for demonstration purposes. In real life the panels are no where near the 33% surface area of my roof.

 

[aesculus]

Your local fire department has complete control over this. It's more than just access. They may have other restrictions too.

So you need to make your case to or understand the local fire authorities rules here. They can override just about anything one way or the other.

 

[holeydonut]

Your local fire department has complete control over this. It's more than just access. They may have other restrictions too.

So you need to make your case to or understand the local fire authorities rules here. They can override just about anything one way or the other.

Is this something you can just call up and ask?

 

[BGbreeder]

Is this something you can just call up and ask?

Sorry for the stress and hair pulling.

Pre-Covid, you could have wandered into most of the local city/county building permit offices and asked. In these times, my local AHJ has gone to an email address that they respond to after a bit. Yours may have that service. YMMV, but do bear in mind that any "over the counter" advice is always non-binding. They tend to say that X, Y, or Z are the issues of concern, but there may be something else that attracts the attention of the person who actually reviews your permit. Like the guy who decided that a stain on an aerial view of the driveway 100' away represented a land slip, and therefore a full geotechnical site review of the area around our deck. Or the planner that insisted on a full archeological review of the area under the deck repair (same size deck, same location, just replacing rotting wood). We dodged one, and not the other. The geotechnical engineer got out of his truck, looked around and said "you have to be kidding me." Ten minutes later he was leaving, but we still had to fork over for a full geotechnical evaluation.

As @aesculus points out, there are lots of variations on "the" rules, and it boils down to what your particular AHJ decides in your case. If it is gong to make a big difference for you, I would suggest looping in a professional with experience who may be able to suggest a proposal that is (more) likely to prevail in your particular area. e.g. a catwalk on the east side.

We have a somewhat similar roof, asymmetric, with the prime roof for solar panels being fractured into different "rooflets" of slightly different slopes, with perhaps 15" of maximum height between each rooflet. The AHJ decided that each rooflet was a different roof, and required the spacing on all edges, not just an edge of a rooflet, to give fire fighters their choice of access lines. The solar roof faces away from the street, so the solar panel rooflets are not the easy access to the roof, but only an access.

All the best,

BG

 

[holeydonut]

Thanks BG.

I guess, this COVID situation plus California PSPS situation plus the Presidential malarkey must be making local inspectors and stuff super paranoid. I guess they're taking the a very conservative assessment on this ridge/walkway access thing.

 

[aesculus]

Thanks BG.

I guess, this COVID situation plus California PSPS situation plus the Presidential malarkey must be making local inspectors and stuff super paranoid. I guess they're taking the a very conservative assessment on this ridge/walkway access thing.

Don't forget to add on all the homes that were destroyed and now need to be inspected and rebuilt. Even after last Falls events my local rural building inspectors were sent to other communities to help out. That slowed our counties inspections because of that.

 

[Vines]

With all the BS around fire rule changes in NorCal, I guess Sunrun is taking way more time assessing my design before it goes in. A new wrinkle has arisen around the interpretation of California Residential Code (CRC) R324.6.2

My house is designed weird - it's a two story home with a vaulted ceiling that is asymmetrical to the house. So one of my roof lines is shallow, but the Southeast facing roof line is rather steep. And, neither roofline points toward the street. The only way to access my roof with a ground-ladder is to go up the West side of the house and hoof it over to the East side. There is no way to put a ladder on the East side and get to the roof since my neighbor's fence gets in the way.

That means if there's a fire, I think the pathway to the ridge line of the roof is to put a ladder up on the West side and work East. So, I think this means I only needed 18 inches from the roof ridge to the PV array.

Butttt an alternate interpretation of this is that a ladder truck parking on my driveway could directly access the roof on the Southeast side. This means the Southeast roof becomes the access point, and I will now need 36" set back from the ridge. With this interpretation, the upper course of solar panels would need to be mounted in "landscape" mode and I'd lose panels.

I can't tell what is a reasonable interpretation of R324.6.2... isn't 18" sufficient from the ridge even if the access point doesn't face the street?

I'm about at wits end being a PM on my PV + Battery installation ... I feel like if I got some investment together I could start a clean energy company. What do you think @Vines and @wwhitney ?

I've attached two pictures showing a crude mock-up of the issue.
Picture 1 shows the landscape orientation that would give a much fatter pink zone (36" from the ridge)
Picture 2 shows the portrait orientation that I thought I was getting before all this BS around fire codes (18" from the ridge)


One last note: I've intentionally made the solar panels HUUUGGEE for demonstration purposes. In real life the panels are no where near the 33% surface area of my roof.

Code is clear and easy on this:
If the array occupies 33% or less of your total roof area, then any ridge with modules on that plane needs 18" clear on either side free of modules.
If you exceed 33% PV coverage of the whole roof and do not have fire sprinklers, then the setback is 36" clear on both sides of the roof. if you have fire sprinklers you can go up to 66% coverage with the same 18" setbacks.

In any case you need (2) 36" wide pathways from the eave to the ridge for each ridge modules are installed under. One of those 2 pathways must be on the street or driveway side of the house. If i was drawing that, I'd have one path there from the west roof with the lower slope to satisfy street side access and the other from the backyard somewhere there is another 36" wide path..

You are correct and your alternate view is not code required, though an AHJ might need "education" I had one AHJ try very hard to require 18" on either side of a hip until I pointed out about 6 times that the code says horizontal ridge, not every ridge.

Do you really want more of this? I have a job for you if so lol.

 

[holeydonut]

Code is clear and easy on this:
If the array occupies 33% or less of your total roof area, then any ridge with modules on that plane needs 18" clear on either side free of modules.
If you exceed 33% PV coverage of the whole roof and do not have fire sprinklers, then the setback is 36" clear on both sides of the roof. if you have fire sprinklers you can go up to 66% coverage with the same 18" setbacks.

In any case you need (2) 36" wide pathways from the eave to the ridge for each ridge modules are installed under. One of those 2 pathways must be on the street or driveway side of the house. If i was drawing that, I'd have one path there from the west roof with the lower slope to satisfy street side access and the other from the backyard somewhere there is another 36" wide path..

You are correct and your alternate view is not code required, though an AHJ might need "education" I had one AHJ try very hard to require 18" on either side of a hip until I pointed out about 6 times that the code says horizontal ridge, not every ridge.

Do you really want more of this? I have a job for you if so lol.

Lol thanks Vines, as always your knowledge level is like... way too high haha.

I think I may need to start looking for new work if my management team knew how much time I was spending on TMC trying to get my system set up instead of doing my normal day job hah.

I also feel like Sunrun is blaming the panel reduction on fire codes (something a layperson may casually understand)... but the actual problem is the 120% rule and 40A breaker limit.

With 23 LG 345 watt panels on Enphase IQ7+, the system would be 7,935 wP. Assuming Enphase's spec sheet indicating 97% DC to AC efficiency @ 240v, this would be JUUUSSTTT a bit over 40A when factoring in the NEC's 125% requirement on continuous load. This rounding pain seems a tougher pill to swallow than just blaming the fire risk.

((7,935 w * 0.97) / 240v) x 125% = 40.01A ... And apparently you're always supposed to round up.

Maybe Sunrun is getting cold feet on this when someone does maths on my installation. So maybe they're looking for an excuse to take 1 panel out.

I'm just glad the world didn't end after the general election.

 

[wwhitney]

With 23 LG 345 watt panels on Enphase IQ7+,

You just need to know the inverter's "maximum continuous output current," it doesn't matter what panels are installed. For the IQ7+, that current is 1.21A for a 240V system. So the calculation for the 120% rule is 23 * 1.21 * 125% = 34.8A.

Also, for load calculations, there is a rule that current can be rounded to the nearest amp (220.5(B)). Not sure if it would apply to Article 705 calculations.

Cheers, Wayne

 

[holeydonut]

You just need to know the inverter's "maximum continuous output current," it doesn't matter what panels are installed. For the IQ7+, that current is 1.21A for a 240V system. So the calculation for the 120% rule is 23 * 1.21 * 125% = 34.8A.

Also, for load calculations, there is a rule that current can be rounded to the nearest amp (220.5(B)). Not sure if it would apply to Article 705 calculations.

Cheers, Wayne

Cool - thanks Wayne!

So I have a ways to go and still fit under the 40 A limit! They should be throwing more panels on my roof!

 

[charlesj]

Code is clear and easy on this:
If the array occupies 33% or less of your total roof area, ...

I would think "total roof" meaning all roof sides on that story, 2 roof planes or 4 roof plane area?
I guess on a two sided roof only that 33% is gobbled up quickly.

 

[Vines]

I would think "total roof" meaning all roof sides on that story, 2 roof planes or 4 roof plane area?
I guess on a two sided roof only that 33% is gobbled up quickly.

I interpret total roof to be the total roof area when viewed from the plan view, on all stories and surfaces.

 

[Vines]

Lol thanks Vines, as always your knowledge level is like... way too high haha.

I think I may need to start looking for new work if my management team knew how much time I was spending on TMC trying to get my system set up instead of doing my normal day job hah.

I also feel like Sunrun is blaming the panel reduction on fire codes (something a layperson may casually understand)... but the actual problem is the 120% rule and 40A breaker limit.

With 23 LG 345 watt panels on Enphase IQ7+, the system would be 7,935 wP. Assuming Enphase's spec sheet indicating 97% DC to AC efficiency @ 240v, this would be JUUUSSTTT a bit over 40A when factoring in the NEC's 125% requirement on continuous load. This rounding pain seems a tougher pill to swallow than just blaming the fire risk.

((7,935 w * 0.97) / 240v) x 125% = 40.01A ... And apparently you're always supposed to round up.

Maybe Sunrun is getting cold feet on this when someone does maths on my installation. So maybe they're looking for an excuse to take 1 panel out.

I'm just glad the world didn't end after the general election.

No problem, I pop in on breaks and to give my brain a rest in between doing most of this for work lol. We are serious about hiring though and need like 5 more installers at a minimum.

 

[charlesj]

I interpret total roof to be the total roof area when viewed from the plan view, on all stories and surfaces.

Just to be clear then, if garage is attached with its own roof but no panels on it and 2nd story roof has hips hence 4 sides with only one side with panels both garage roof and the totality of roof surface on 2nd story is the total roof area?
Thanks.

 

[Vines]

Just to be clear then, if garage is attached with its own roof but no panels on it and 2nd story roof has hips hence 4 sides with only one side with panels both garage roof and the totality of roof surface on 2nd story is the total roof area?
Thanks.

That is my understanding, the code makes no division between stories or use of the interior of the structure except to consider total roof area.

 

[BGbreeder]

That is my understanding, the code makes no division between stories or use of the interior of the structure except to consider total roof area.

Thanks so much for the detailed information. I'm always learning something from you and your posts.

Interesting. That would put us in the over 33%, but under 66% rule bucket. We have one continuous horizontal ridge, except for the garage, which is a separate building, but with solar on it as well.

AHJ do seem to make life interesting.

All the best,

BG

 

[Vines]

Thanks so much for the detailed information. I'm always learning something from you and your posts.

Interesting. That would put us in the over 33%, but under 66% rule bucket. We have one continuous horizontal ridge, except for the garage, which is a separate building, but with solar on it as well.

AHJ do seem to make life interesting.

All the best,

BG

One thing to consider is that the modules are slightly smaller than they are from perpendicular to the glass.

Measure from a plan view, so you can decrease the module size in one dimension in proportion to the projected size based on the roof slope.

If you are over the 33%, 36" ridge setbacks aren't usually a deal breaker they just make the design less optimal. Also sometimes you can cut and cover your stink pipe vents, depending on your jurisdiction, so that may open up roof that was otherwise not useful.

 

[Vines]

That is my understanding, the code makes no division between stories or use of the interior of the structure except to consider total roof area.

Actually, there is a detail that I should expand on.

Detached garages and other non habitable structures are exempt from the fire setbacks and pathways, so my statement above isn't totally correct.

Roofs less than 2:12 are also are also technically exempt, but the fire officials still like them to have some walkways shown.