If you have spent any time searching for a small second home on your property, you have run into four different words for what is often the same building. Granny flat. Granny pod. Casita. ADU. Builders use them interchangeably, listing sites use them interchangeably, and your neighbor probably uses a fifth one.
Only two of those words appear anywhere in California law. Knowing which two — and which building each name actually describes — is the difference between a project that gets approved in sixty days and one that stalls at the counter because nobody can tell what you are asking to build.
Granny Flat vs ADU: The Short Answer
California’s planning statutes recognize exactly two things: the accessory dwelling unit (ADU) and the junior accessory dwelling unit (JADU). Everything else on that list is vernacular. “Granny flat” is what people called them before the state wrote rules; “casita” is regional usage from the Southwest; “granny pod” is largely a product category rather than a building type.
When you apply for a permit in Monterey County, your application will say ADU or JADU. What you call it at the dinner table is entirely up to you.
What Is a Granny Flat in California?
The oldest of the four names, and the closest in meaning to what the statute now calls an ADU. A granny flat is a self-contained second dwelling on a single-family lot — its own kitchen, its own bathroom, its own entrance — historically built so an aging parent could live independently but nearby.
The name stuck because that was the common use case for decades. It has broadened since. Today the same building houses adult children, a long-term tenant, a home office with a shower, or the owners themselves once they downsize and rent out the main house.
If you are searching for granny flat plans in California, what you want is a set of ADU construction documents. Same building, current vocabulary.
What Is a Granny Pod, and Is It an ADU?
This is the one that trips people up, and it is worth being blunt about.
“Granny pod” almost always refers to a manufactured, factory-built unit that arrives on a truck and is set on a prepared pad — often marketed with accessibility features and remote health monitoring for an elderly parent. It is a purchased product, not a designed building. You buy it from a manufacturer, much as you would buy a modular office or a prefab studio.
That is a legitimate way to add a unit, and for some households it is the right one. It is also a completely different transaction from the one described on the rest of this page. A prefab unit still needs a site plan, a foundation design, utility connections and a permit — but the building itself is designed by the manufacturer, and there is nothing for a drafting firm to draw.
So: if you want a unit designed around your lot, your setbacks, your slope and your existing house, you are looking for a custom ADU. If you want a unit delivered on a trailer, you are looking for a manufacturer. We do the first and we are happy to say so plainly — it saves everyone a phone call.
Is a Casita an ADU?
Spanish for “little house,” and common usage in Arizona, New Mexico and Southern California. On the Monterey Peninsula you will hear it less often, and when you do it usually means one of two things:
- A full ADU — detached, kitchen and bath, someone could live in it year-round.
- A guest room without a kitchen, detached from the main house. This is not an ADU at all. Without cooking facilities it is classed as accessory living space, and it follows a different and generally simpler permitting path — though it also cannot be legally rented as a dwelling.
That second case matters. If your goal is a spare room for visiting family and you have no interest in rental income, a detached guest room may get you there with less process than a full ADU. If you ever want to rent it, it needs a kitchen, and it needs to be permitted as an ADU from the start. Retrofitting a kitchen into a permitted guest room afterward means going back through the whole approval.
ADU vs JADU: The Two Terms California Law Actually Uses
An ADU is an independent living facility on a lot with an existing or proposed primary dwelling. It has permanent provisions for living, sleeping, cooking and sanitation. It comes in three shapes:
- Detached — a separate building in the yard.
- Attached — sharing at least one wall with the main house, but with its own entrance and its own systems.
- Conversion — an existing garage, workshop or basement turned into a dwelling.
A JADU is the small one: up to 500 square feet, carved out of the walls of the existing single-family home. It can have an efficiency kitchen rather than a full one, and it is allowed to share a bathroom with the main house. Owner-occupancy requirements generally still apply to JADUs, which is the main practical difference from a standard ADU — confirm the current position for your parcel before you plan around rental income.
A JADU is, in the most literal sense, the original granny flat: a room in the house, made independent. If what you are actually picturing is a suite for a parent inside your existing footprint, this is the cheapest and fastest version of the idea by a wide margin. We cover the full definition in what qualifies as an ADU in California.
Granny Flat Size Limits in Monterey County
Whatever you call it, these are the limits your drawings have to work inside:
| Type | Maximum size | Notes |
|---|---|---|
| Detached ADU | Up to 1,200 sq ft | Typically 16 ft height, 4 ft side and rear setbacks |
| Attached ADU | 50% of the existing living area, or 1,200 sq ft — whichever is less | A 1,600 sq ft house caps the attached unit at 800 sq ft |
| Conversion | The existing footprint | No additional setback required for an existing structure |
| JADU | 500 sq ft | Within the walls of the existing home |
Two thresholds sit on top of that and move the budget more than any design decision:
- 750 square feet. Below it, state law exempts the unit from impact fees entirely. At or above it, they apply and they vary by district. Dropping a design from 800 to 740 square feet is frequently the single cheapest change available.
- The coastal zone. A parcel inside it may need a coastal development permit on top of the building permit, which adds both fee and review time. Ministerial approval does not always reach into the coastal zone, and much of the Peninsula is in it.
Both of those are covered in more depth in ADU plans in California: what you can build and what actually gets approved.
Which Type of ADU Do You Actually Need?
A quick way to land on it:
- You want a separate building in the yard that someone could live in permanently → detached ADU.
- You want to convert the garage → ADU (conversion). Usually the least expensive route to a legal second unit.
- You want a suite inside the house for a parent, with its own entrance → JADU.
- You want a guest room with no kitchen and no rental plans → accessory living space, not an ADU.
- You want a unit delivered on a truck → a manufactured unit from a supplier, with a site plan and foundation drawn locally.
Getting Granny Flat Plans Drawn for Your Lot
Whichever name you started with, the permit application needs the same thing: a complete set of construction documents showing the unit, the site, the setbacks, the utilities and the structural work. In Monterey County a complete ADU application must be acted on within sixty days — the clock starts when the set is complete, which is the part most projects get wrong.
Renovation Drafting & Design produces those sets. We are a drafting and design firm, not a builder and not an architecture practice: we draw what gets permitted, and your contractor builds it. If you want to see what that involves, start with our ADU design service, or look at how the same work goes in Monterey, Carmel, Pacific Grove, Pebble Beach and Carmel Valley.
Granny Flat and ADU FAQs
Is a granny flat the same as an ADU?
In practice, yes. “Granny flat” is the informal name for what California law calls an accessory dwelling unit — a self-contained second home on a single-family lot with its own kitchen, bathroom and entrance. Your permit application will say ADU.
What is the difference between a granny pod and an ADU?
A granny pod is usually a manufactured unit bought from a supplier and delivered to your lot. An ADU is a category in state law that includes custom-designed units, attached units and garage conversions. A granny pod can be an ADU once it is permitted, but the building itself is designed by the manufacturer rather than drawn for your site.
Can I get granny flat plans for California, or do they need to be custom?
Stock plans exist, but they are rarely permit-ready in Monterey County. They do not account for your setbacks, slope, soil, coastal designation or the structural work of tying into an existing house. Most stock sets end up needing a local drafting firm to adapt them, which is why starting with drawings made for your parcel is usually the shorter path.
Is a casita an ADU?
It depends on whether it has a kitchen. A detached building with permanent cooking facilities is an ADU. A detached guest room without a kitchen is accessory living space — a simpler permit, but it cannot be legally rented as a dwelling.
How big can a granny flat be in Monterey County?
A detached unit can generally be up to 1,200 square feet. An attached unit is limited to 50% of the existing home’s living area or 1,200 square feet, whichever is less. A JADU is capped at 500 square feet. Note that staying under 750 square feet exempts the unit from impact fees under state law.
Do I need owner occupancy for a granny flat?
Owner-occupancy requirements generally still apply to junior ADUs. The position on standard ADUs has changed several times in recent years, so confirm the current rule with Monterey County for your parcel before planning around rental income.