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FAR for the exterior staircase for a second floor ADU

M

mirzaei.hamid@gmail.

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Hi Everyone,

I am new to this thread. I was wondering if you can help me with this simple question (that the city was not willing to help me for, maybe because I asked them a few questions before).

I am building (designing) an ADU on the second floor of a single family home with an exterior stairway on the side of the lot as the ADU entrance.

I was wondering which of the following is true for the exterior stair case:

1- is not counted in FAR because it is not covered.
2- is counted in FAR for ADU.
3- is counted in FAR for the main house.

The city is Palo Alto. Just as an example, please take a look at the exterior staircase we are considering.


I really appreciate your help.

1704707028038.png
 
FAR is "Floor Area Ratio," and unless California added it in, floor area ratio is not regulated by the building code. It's a zoning concept that has to do with how many total square feet of floor area you're allowed to put on 'X' square feet of land.

Question to the OP: Why would the FAR be applied against either the primary residence or the ADU? My exposure to floor area ration as a planning tool doesn't make any distinction between which of multiple buildings on a site houses the floor area(s). Floor area ratio limits the total square footage of floor area allowed on the site.

The specific regulation under which you are operating may treat it differently. You are going to need to read and understand the regulation.
 
I agree with YC .. this is a zoning issue, and you'll need to review their description of what is to be included (or may be ignored) in the definitions.

As an aside, one jurisdiction I worked in had a zoning provision that the building setbacks were actually to be measured to the roof overhang - not the exterior wall at all. I believe they finally changed that in their ordinance because it was such a pain for the Building Department to try and police.
 
Thanks YC and MtnArch. I have limitations defined for FAR (and lot coverage) for the main house and ADU is exempt from that as long as it is under 800 sqft.

That is why I need to know for which one this exterior stairs belong. I attached the summary of FAR above. I can see the following in the code, but it does not necessarily explain exterior stairs.

1704734846293.png
 
How are you seeing that the ADU is exempt? I don't see that in there.

I'm going to make a wild guess that the regulations exempt ADUs that are in separate structures on the parcel. What you have is an apartment within the primary structure. Is this a new building, or are you carving an ADU out of an existing single-family residence?

To address the specific question, though, based on the tabulation you provided above and the rendering of the entrance, the stair itself is uncovered and appears to be less than 12 feet high, so that looks to me like it's exempt.

The entry porch/landing has a roof over it. That's a second floor roofed porch, so IMHO it counts once. But I can't understand the diagrams in the link that discuss "vaulted" entry features, and why they count twice.
 
Thanks very much for your time!

It is a new building. And we are designing it. (Construction of Attached ADU within the space of a proposed single family home)
Here is the ADU rules, in the second to last row (in foot note) it says 800 sqft exempt in FAR and lot coverage.
1704740989110.png

I also think that the exterior stairs might be considered an entry feature (less than 12' high). Let me try to understand. You are saying only the landing (1 or 2 m^2) is counted, you only have doubt that it may count twice i.e., 2*1 m^2. did I understand correctly?

I have this info from the code as well, maybe the landing on the upper floor actually falls under category 6 here (roofed balconies on upper floor)?

1704741791576.png


Here it says the "stairway" are included, but if it is interior stairs, what is so special about it that it is included in the lot coverage discussion?
1704741472195.png
 
I candidly admit that I'm out of my league here. The entire concept of exempting ADUs from calculations of floor area ratios runs completely contary to the fundamental concept of the purpose of having floor area ratios at all. I am certainly not in a position to interpret regulations I admittedly don't understand, and which the editor in me says are written rather poorly.

I do think the upper entrance landing is a balcony that would be included. BUT ... it serves the ADU, so if the ADU is exempt, shouldn't both the stair and the balcony also be exempt? But that would mean that their area must be included in the 800 square feet allowed for the ADU. If the area of the ADU within the walls is +/- 800 square feet, then I'd say the balcony counts. Based on the new information you provided, it seems clear that it only counts once.

The new information also says that "projecting elements" such as stairways count. The stair in your rendering is a projecting element, on the exterior of the building. Based on this, I'd say it counts. This same provision also reinforces that the entry landing/balcony counts.
 
Thank you for your time replying to me and reducing my headache after searching the codes for several days!

ADU can be made smaller to keep things in limit. There are two concepts 1- lot coverage 2- FAR. ADU helps to get up to 800 sf exemption from both.

To understand correctly, your impression is that the stairway:

1- Counts against the LOT COVERAGE as a projecting element.

2- But if it serves ADU it might be considered a part of ADU and exempt from lot coverage (ADU up to 800 sf)

2- But in any case it seems like it doesn't count toward FAR (as part of the main house) because it does not have a roof ( at least I don't find the rule).
 
My opinion on this (these) question(s) is worth exactly what you paid for it. The only opinion that matters is the opinion of whoever administers these silly regulations.

I get that California wants to encourage ADUs as a way to combat its housing shortage. Enacting regulations that may have certain elements count as lot coverage while simultaneously NOT count as lot coverage (which is, after all, what floor area ratio is a variety of) offends my sense of logic. I respectfully decline further comment.
 
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