All ADU Regulations

Menlo Park, California

Menlo Park has updated its ADU Guidelines to comply with new state laws. Below are the up-to-date requirements to build an ADU in the city.

March 2, 2023
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t is now easier than ever to build an ADU in Menlo Park, as the Menlo Park City Council has adopted state legislation that makes ADU development more accessible. In fact, permits must now be processed in under 60 days, as opposed to the previous 120. ADUs are an affordable form of alternative housing, and recent changes in laws can help solve the state-wide housing shortage.

Read on to find out what the new legislation means for you as a homeowner, and how it makes ADU development more convenient for you.

General ADU requirements

While there is no minimum lot size requirement to be eligible for an ADU, your ADU itself can be a minimum of 150 sq.ft.

The specifications for your ADU depends on the type of ADU you are building; are you building a detached, attached or conversion ADU?

Generally, however, your ADU should have independent and permanent facilities for:

  • Living
  • Eating
  • Sleeping
  • Sanitation
  • Cooking
  • Exterior access that is separate from the primary dwelling

Your ADU kitchen is required to have:

  • A sink with running water
  • Countertops and cabinetry
  • A refrigerator
  • A permanent range/cooktop

While Junior ADUs (JADUs) must have an entrance that is separate from the primary dwelling, they may share a bathroom/sanitation facilities with it.


All properties zoned for single family, two-family or multifamily use may be eligible to build ADUs.

Unless an ADU is associated with an affordable housing nonprofit, it may not be sold separately from the primary residence.


As of 2023, the fees involved in building an ADU are proportional to the size of the project. Here are some of the fees you can expect to pay in the City of Menlo Park:

  • Plan check fees
  • Residential, building, and green code fees
  • City impact fees (for ADUs above 750 sq.ft.)
  • School impact fees

The exact amount you’d pay for permit fees would depend on the location of your project, its complexity, and a number of other factors. In the case of ADUs larger than 750 sq. ft., impact fees are generally proportionate to the size of your property. School impact fees are likely to cost between $3-$5 per sq. ft. of your ADU.

Some fees have been waived in some zoning districts, so speak with your Cottage consultant to see where you can cut costs.

Number of units

The number of ADUs you’re able to build depends on how your lot is zoned:

  • Lots zoned for single family use may add 1 ADU and 1 JADU.
  • Lots zoned for two-family or multi-family may add up to 2 detached ADUs per lot or up to 25% of the existing units in the building if converting existing non-living space (conversion ADUs).

Building size

Size limits depend on the type of ADU you’re building and the specific location of your property. Generally, in the City of Menlo Park, you can build an ADU or JADU according to the following limits:

  • Single-family and multi-family attached ADUs can be 1,000 sq.ft. or 50% of the existing area of the primary dwelling, whichever is greater
  • Single-family and multi-family detached ADUs can be up to 1,000 sq.ft.
  • Regardless of size or type, ADUs may have a maximum of two bedrooms
  • JADUs can be up to 500 sq.ft.

Building height

Detached ADUs can reach a maximum height of 16 feet; however, ADUs over 800 sq. ft. can be 17 ft in height. Attached ADUs can reach the same height as the main structure, assuming they comply with the standards for that zone.


Specific requirements for setbacks may vary depending on the zoning district you are building in. However, while in keeping with these regulations, detached ADUs under 800 sq. ft. are required to have minimum setbacks of 4 ft from the side and rear lot lines. Detached ADUs that are more than 800 sq.ft. should have a minimum setback of 10 ft from the rear lot lines.


According to state law, if fire sprinklers aren’t required for your primary residence, then they are not required for your ADU either. You may set up alternative facilities for fire protection.


Parking regulations depend on the type of ADU you’re building. Conversion ADUs and JADUs generally don’t require any parking. However, detached and attached ADUs usually require one parking spot unless any of the following are true:

  • The ADU is located within one-half mile walking distance of public transit.
  • The ADU is located within an architecturally and historically significant historic district.
  • The ADU is part of the proposed or existing primary residence or an accessory structure.
  • On-street parking permits are required but not offered to the occupant of the accessory dwelling unit.
  • There is a car share vehicle located within one block of the accessory dwelling unit.


Owner occupancy is not a requirement for permitting an ADU from January 1, 2020 until January 1, 2025. This is a great opportunity for rental property owners to increase their yields in a cost-effective way.


While long-term rentals are permitted for ADUs, short-term rentals are not permitted in the City of Menlo Park. The minimum rental period for ADUs is 30 days. Importantly, short-term rental platforms like Airbnb do allow homeowners to rent units for longer term periods (30 days or more).


Are you in a creek protection area? Do you have a utility easement over your property? Reach out to us and we’ll help you build a customizable ADU to fit your unique property characteristics and local regulations!


Is building an ADU a good investment?

Yes, it is a reliable long-term investment. Not only does it add value to your property, but you can rent out your ADU and earn passive income.

What is the smallest ADU you can build in Menlo Park?

ADUs in Menlo Park can have a minimum living area of 150 sq.ft.

What is the ROI on an ADU in Menlo Park?

While the exact ROI would depend on local rental markets, total construction costs and project financing, the addition of an ADU contributes significantly to the long-term value of your home. Short-term rental income may also help to offset building costs!

How long does it take to build an ADU in Menlo Park?

The time taken to plan, design, and build an ADU in Menlo Park depends on the location, type and scope of the project, among other things. However, the physical construction of yourADU can commonly take four to eight months.

How much does an ADU increase property taxes in Menlo Park?

You can expect to pay 1-1.5% of the value of your ADU in additional property taxes.

Can you build a 2 story ADU in Menlo Park?

As the height limit for an ADU is 16 ft, it is unlikely that you will be able to accommodate 2 stories.

What is the difference between an ADU and a guest house?

ADUs are fully equipped with the facilities required to live there independently and permanently. Guest houses, on the other hand, are not always self-contained and may not include kitchens.

Design and build with confidence.