What Type of Structures Can Be Built on a Residential Lot in San Diego?

By Sean Canning

In this video, I offer a brief explanation of the five main residential building topologies in the city of San Diego, California.

While some of these will be similar to other topologies outside of the city of San Diego, this video is specifically addressing topologies available to us in the city of San Diego on residentially zoned lots.

The Standard Dwelling Unit

Your first type of topology is going to be your standard dwelling unit. Sometimes these are referred to as the main dwelling unit or dwelling unit proper.

You may have a single-family dwelling unit or multifamily dwelling unit. But the important thing to understand about the dwelling unit is you have to first build a dwelling unit on any property in San Diego before the other residential topologies become available to you.

So this means you can't build a garage or an accessory dwelling until you have that first dwelling unit proper.

Now, dwelling units in San Diego have to respect the setbacks. They generally require parking although there are certain areas where you can avoid parking (if you provide certain parking amenities).

You can think of your primary dwelling unit as simply your first home on the property (or the first residential home built on any lot).

Accessory Dwelling Units (ADU)

Now the next typology after the dwelling unit is going to be your accessory dwelling unit.

Accessory dwelling units have gotten very popular in the last three to five years in San Diego. Particularly since 2020 when the state of California issued its new accessory dwelling unit regulations. These took a lot of the regulations out of the hands of the municipalities in an effort to solve the housing crisis that we're going through right here in California.

The accessory dwelling unit is very interesting, especially in San Diego.

Accessory dwelling units can be built on RS zoned lots or RM zoned lots. And they can be attached or they can be detached. In certain cases, you can build more than one accessory dwelling unit. And in some specific cases, you can build essentially an infinite amount of accessory dwelling units leveraging the affordable housing regulations. And of course under the base floor area ratio for the law.

But you can think of an accessory dwelling unit as a second house or maybe a guest house. Note that “Guest House” is not used as a term in the municipal code. They're using the term accessory dwelling unit which is what you will see if you review San Diego’s municipal code.

The accessory dwelling unit in the city of San Diego does not have to have a rear or side yard setback. But you do have to have the same front yard setback or street-side yard setback that the primary dwelling unit would have.

Junior Accessory Dwelling Unit (JADU)

Now the next topology after the ADU or accessory dwelling unit is the junior accessory dwelling unit or JADU. The JADU is also an interesting typology - it's limited to 500 square feet, and it needs to be attached to another structure. In the city of San Diego, as far as I understand, they're allowing these to be attached to accessory dwelling units, but also could be attached to the dwelling unit proper. So the important thing to know about the JADU is that you have to attach this one.

Now the interesting thing about the JADU is it's allowed to share a bathroom from the unit it's connected to. While there are only a few reasons why you'd want to do this, it is available to you if you want to share a bathroom.

One of the reasons you may want to share a bathroom is because efforts certain point of adding plumbing fixtures to a property, you're going to trigger a water meter upgrade which could be a $10,000 cost.

So in certain cases, you may benefit from sharing that bathroom and avoiding that cost.

Guest Quarters

Okay, so we've talked about the dwelling unit, the accessory dwelling unit, and the junior accessory dwelling unit, the next typology is going to be the guest quarters.

The guest quarters could be looked at kind of like a pool house. So the guest quarters are not meant for people to live long term. Really, it's not even available for short-term rent.

But it is another structure that you can put on your lot in addition to these other structures. For example, you could build a home office or a pool house.

So in certain cases, a guest quarter is a good decision.


The last topology I'd like to mention is your garage. And your garage can be attached or detached. The benefit of the garage (especially under the new ADU regulations) is not only can we park in the garage, but it leaves available future development opportunities.

Because in the RMS no locks you can convert your garages into accessory dwelling units without using the affordable housing density bonuses, or excuse me, the affordable housing regulations. So in certain cases, building a garage now, planning for a future Edu may be a very strong move.

That's a quick explanation of five residential topologies that you're going to see in the city of San Diego. If you are interested in determining your residential development possibilities, read this blog post for a quick 5 step process you can use.

If you have a residential lot that you are considering developing on, feel free to reach out and schedule a meeting with me to discuss your project. I’ll help you map out a clear strategy, answer any questions you have, and offer helpful advice for getting your project done faster by sharing with you have I’ve learned from designing & permitting homes in the city of San Diego for 10+ years.

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