Building Code Requirements for ADU Kitchens and Bathrooms
Your ADU's kitchen and bathroom must meet California building code requirements. Understanding these rules upfront prevents costly redesigns during plan check. Here's what you need to know.
ADU Kitchen Requirements
A full ADU (not a JADU) requires a complete kitchen that includes:
Required Appliances and Fixtures
- Cooking appliance: Range/oven or cooktop. A microwave alone does not qualify
- Refrigerator space: Dedicated space with an electrical outlet for a refrigerator
- Sink: Kitchen sink with hot and cold water supply
- Counter space: Adequate food preparation area
- Storage: Cabinets or shelving for food and cooking supplies
Plumbing Requirements
- Hot and cold water supply to the sink
- Proper drain connection with P-trap
- Dishwasher connection (rough-in recommended even if not installing immediately)
- Adequate water pressure
Electrical Requirements
- Dedicated 20-amp circuits for kitchen countertop outlets
- GFCI protection for all outlets within 6 feet of the sink
- Dedicated circuit for refrigerator
- Range/oven on its own circuit (50-amp for electric, or gas connection)
- Adequate overhead and task lighting
Ventilation
- Range hood vented to the exterior (recirculating hoods may not meet code in all jurisdictions)
- Minimum ventilation rates per California Mechanical Code
- Makeup air may be required for high-CFM range hoods
JADU Kitchen Requirements (Efficiency Kitchen)
Junior ADUs have relaxed kitchen requirements. A JADU only needs an efficiency kitchen with:
- Small sink
- Counter surface (minimum 15 inches of counter space)
- Cooking appliance (can be a plug-in appliance like a hot plate or microwave)
- Refrigerator (can be compact/mini-fridge)
- Food preparation counter
This makes JADUs significantly easier and cheaper to build.
ADU Bathroom Requirements
Every ADU must have at least one bathroom with:
Required Fixtures
- Toilet: Water closet with proper clearances (minimum 15 inches from center to side wall, 30 inches of clear space in front)
- Sink/lavatory: With hot and cold water
- Bathtub or shower: With hot and cold water and proper waterproofing
Minimum Dimensions
- The bathroom must be large enough to accommodate all fixtures with proper clearances
- A functional bathroom can fit in as small as 36-40 sq ft, though 50+ sq ft is recommended for comfort
Ventilation
- Mechanical exhaust ventilation (bathroom fan) ducted to the exterior
- Minimum 50 CFM intermittent or 20 CFM continuous
- Fan must be connected to a timer or occupancy sensor in some jurisdictions
Waterproofing
- Shower and tub surrounds must be waterproofed to code
- Shower pans must pass a flood test before tiling
- Cement board or equivalent moisture-resistant substrate required
Accessibility Considerations
While not always required for ADUs, building with accessibility in mind is smart -- especially if the ADU is for aging parents. Consider:
- Blocking in walls for future grab bar installation
- Curbless shower entry
- Wider bathroom doorway (36 inches)
- Lever-style faucet handles
Learn more about building an ADU for aging parents and multigenerational living.
Design Tips for Small ADU Kitchens and Bathrooms
For layout inspiration, check out our guide to the best ADU floor plans for maximum rental income.
Kitchen Tips
- Galley layout works best for narrow spaces
- L-shaped layout maximizes counter space in open floor plans
- Full-height upper cabinets add storage without taking floor space
- Under-counter appliances (dishwasher, microwave) save counter space
Bathroom Tips
- Walk-in shower instead of tub saves space and looks modern
- Wall-mounted vanity creates visual space
- Pocket door saves swing clearance
- Niche shelving eliminates need for shower caddies
- Large mirror makes the room feel bigger
If you're building for aging parents, see our complete guide to ADUs for multigenerational living -- accessibility features in the kitchen and bathroom can make all the difference.
> Come to our Anaheim showroom to see full kitchen and bathroom setups -- pick your finishes, feel the materials, and work with our design team.
What Vision ADU Handles for You
We take care of all code compliance so you don't have to worry about it:
- Complete architectural plans that meet all kitchen and bathroom codes
- Structural engineering for plumbing and ventilation penetrations
- Title 24 energy compliance for appliances and lighting
- All permit submissions and plan check responses
- Inspection coordination throughout construction
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Understanding how much an ADU costs will help you budget for the kitchen and bathroom finishes you want. And don't forget to research your city's setback requirements to know how much space you're working with.
Not sure what your ADU kitchen and bathroom should look like? Book a free consultation and visit our showroom to see finished examples and select your finishes.
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