ADU kitchen and bathroom requirements in California

What makes a unit an ADU

The kitchen and bathroom are the legal test. California's definition of an accessory dwelling unit is a unit with “complete independent living facilities” for one or more people, including “permanent provisions for living, sleeping, eating, cooking, and sanitation.” Cooking means a kitchen. Sanitation means a bathroom. A room without both is a guest room, an office or a pool house, not an ADU.

The same definition says an ADU also includes an efficiency unit and a manufactured home. A junior ADU (JADU) is a different category: up to 500 square feet of interior livable space inside a single-family house, which may have its own sanitation facilities or share the house's. If the terms are new, start with what an ADU is and the four types.

Sources: the state's efficiency unit statute, which lets a city allow units as small as 150 sq ft for up to two people with partial kitchen or bathroom facilities, and San Diego's municipal code for guest quarters.

ADU kitchen requirements

State ADU law doesn't list kitchen parts for a regular ADU. It requires permanent provisions for cooking, and the building code fills in the rest. The 2025 California Residential Code, in effect since January 1, 2026, says each dwelling unit must have a kitchen area, every kitchen area must have a sink, and kitchen sinks need hot and cold water.

A workable ADU kitchen has what any apartment kitchen has:

• A sink with hot and cold water, connected to the sewer or an approved septic system.
• A permanently installed cooking appliance, such as a range or cooktop.
• Counter space and cabinets.
• Room for a refrigerator. HCD's handbook glossary describes an efficiency dwelling unit as having a kitchen sink, cooking appliance and refrigerator, which is a good baseline even for a larger unit.
• A vented range hood or exhaust fan, and the outlets and circuits the electrical code requires (see building code basics).

There's no statewide minimum kitchen size. Under the residential code, habitable rooms other than kitchens must be at least 70 sq ft and 7 feet wide, so a kitchen can be a one-wall run along the living room. That's how most studio and small ADU plans fit a full kitchen into 400 square feet.

Efficiency kitchen for a junior ADU

A junior ADU gets a lighter rule. Government Code section 66333 requires an efficiency kitchen with:

• a cooking facility with appliances,
• a food preparation counter, and
• storage cabinets of reasonable size for the size of the unit.

That's the ceiling as well as the floor. HCD's 2026 handbook says a city can't be more restrictive than this definition, so it can't set counter or cabinet sizes, demand specific electrical or gas connections, or require particular appliance types. HCD adds that 220-volt circuits aren't required for an efficiency kitchen.

The statute doesn't mention a sink, but the residential code says every kitchen area must have one, and a JADU without a sink would be hard to rent. Confirm with your city how it applies the sink rule to a JADU. Most owners plan a compact range or two-burner cooktop, an under-counter or apartment-size fridge, and a single-bowl sink. For entrances, size limits and permits, see our full guide to junior ADU rules.

Sources: Gov. Code § 66333; CRC § R326.2 for the sink.

ADU bathroom requirements

Every regular ADU needs its own bathroom, because the definition requires permanent provisions for sanitation. The residential code spells it out: every dwelling unit must have a water closet (toilet), a lavatory (bathroom sink) and a bathtub or shower, connected to the sewer and supplied with hot and cold water.

A shower is enough; you don't need a tub. One bathroom is the legal minimum at any size, though two-bedroom plans often add a second. Snap ADU's March 2026 price list shows a 750 sq ft two-bedroom with one bath and a 1,000 sq ft two-bedroom with two.

Bathroom fixture clearances

The plumbing code sets the minimum space each fixture needs. Roseville's 2025-code bathroom handout summarizes the common ones:

If the ADU is for a parent, plan a curbless shower and a wider door at the design stage, when they're easiest to add. See granny flat vs ADU for aging-in-place features.

Shared bathroom and owner occupancy

Only a junior ADU can share a bathroom with the house. That choice now carries a legal trade-off. AB 1154, in effect since January 1, 2026, ties the JADU owner-occupancy rule to the bathroom:

Source: HCD's handbook, citing Gov. Code § 66333(b) and (e)(2). A JADU that shares the bathroom must have a separate outside entrance plus an interior entry to the main living area. Regular ADUs have no owner-occupancy requirement at all.

A shared bath saves the cost of a new bathroom and its drain lines, and it suits a relative or caregiver. A private bath costs more but lets you rent to anyone without living on the property, and makes the unit easier to rent. JADU rentals must be longer than 30 days either way.

Kitchen rules in San Diego

The City of San Diego follows the state definitions, with a few local points worth knowing:

• JADU kitchen. SDMC § 141.0302 repeats the efficiency kitchen rule: a cooking facility with appliances, plus a counter and cabinets of reasonable size for the unit. Information Bulletin 400 (January 2026) adds that the JADU's kitchen must be separate from the main house's kitchen.
• JADU bathroom and owner occupancy. IB-400 says the owner must live on site unless the JADU has separate sanitation facilities, matching state law. The municipal code text still lists owner residency for every JADU, so ask Development Services which version goes in your recorded agreement.
• Fire walls. Under IB-400, if the house has no sprinklers, a JADU with its own kitchen and its own sanitation that shares a wall with the house may need that wall fire-rated. State law says a JADU isn't a separate dwelling for fire rules, so confirm this at plan review.
• Guest quarters can't have a kitchen. San Diego's guest quarters and habitable accessory buildings (§ 141.0307) may not contain a kitchen or food storage and preparation facilities. A bar sink and a mini fridge are allowed. Add a stove and you need an ADU permit.

For the permit steps, see how to get an ADU permit in San Diego. For the rest of the state rules on size, setbacks and fees, see California ADU laws.

Building code basics

An ADU kitchen and bathroom follow the same codes as any new house. City handouts written for the 2025 codes give a fair summary. These come from Rancho Cucamonga's kitchen handout and Roseville's bathroom handout; San Diego applies the same state codes, but check for local amendments.

Ventilation

• Kitchen. A local exhaust system vented outdoors, at least 100 cfm if it runs intermittently. Recirculating hoods don't count. Ducts must be smooth metal with a backdraft damper, and aluminum flex duct is prohibited.
• Bathroom. An exhaust fan of at least 50 cfm intermittent or 20 cfm continuous in any bathroom with a tub or shower, even if it has an operable window, ducted to the outside.

GFCI and kitchen circuits

• All kitchen countertop receptacles, receptacles within 6 feet of a sink and the dishwasher outlet need GFCI protection.
• Countertop outlets must be placed so no point along the wall is more than 24 inches from one, on at least two 20-amp small-appliance circuits.
• Kitchen circuits also need AFCI protection.
• Bathroom receptacles need GFCI protection, with a receptacle within 3 feet of each sink basin on a 20-amp circuit.

Water and safety

• Kitchen faucets are capped at 1.8 gallons per minute.
• Shower valves must be pressure-balanced, with a 120°F maximum.
• Safety glass is required in shower and tub enclosures.

Your designer handles these on the plans, and inspectors check them at rough and final inspection. Our ADU construction process guide shows where each inspection falls.

What a kitchen and bath add to cost

We found no current, reliable public price for an ADU kitchen or bathroom on its own. What San Diego builders do publish is how these rooms drive the total:

• Snap ADU calls kitchens “the most expensive room of a building” because of cabinets, counters, plumbing and appliances. Its March 2026 San Diego prices include wood cabinets, quartz counters, appliances and fixtures as standard. Tiled showers, islands and premium appliances are upgrades.
• Lars Remodel notes that kitchens and bathrooms “resist simple square-foot scaling,” and lists the efficiency kitchen among the main cost drivers for a junior ADU.

Because kitchens and baths don't shrink with the unit, small ADUs cost more per square foot: about $600 at 500 sq ft versus $425 at 1,000 sq ft in Snap ADU's figures. For the full breakdown, see what an ADU costs in San Diego or try the ADU cost calculator.

Planning the kitchen and bathroom

• One wet wall. Put the kitchen sink and bathroom back to back so they share drain and vent lines.
• Converting? Follow the plumbing. In a garage or JADU conversion, the distance to the existing sewer line drives cost. A JADU can't be charged as a separate unit for water, sewer or power connections, but the trenching and new lines are still yours. See the garage conversion ADU guide and basement and attic ADUs.
• Choose appliances before plans. Range width, fridge depth and whether you want a dishwasher or stacked laundry set the cabinet layout and circuits.
• Pick finishes early. Agree on cabinet, counter, tile and fixture allowances in the contract, so upgrades are priced before work starts.

More layout ideas are in ADU design ideas and ADU floor plans. When you're ready for bids, compare verified ADU builders in San Diego, check a contractor's license, and read how to hire an ADU contractor before you sign.

Common questions