Is there a minimum lot size requirement to build an ADU?

No.

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

An ADU must have a kitchen, bathroom, and living space. A guest house or pool house typically includes a bathroom but not a kitchen 

If a property has a guest house or pool house which was built with permits before the ADU ordinance can the owner convert it to an ADU?

Yes. If the building doesn’t have a kitchen and bathroom, then they will need to be added. That construction would require a building permit and would be subject to all current codes. 

If a property has a guest house or pool house which was built with permits before the ADU ordinance can the owner build a new ADU instead of converting?

Yes, as long as  it complies with all current Town codes and State requirements. However, if the guest/pool house already has a kitchen and bathroom, then it is considered an ADU and another ADU cannot be added to the property. 

What are the benefits of converting an existing space rather than building a new ADU?

Converting existing space is far less expensive and requires less time than building a new unit.  It’s an eco-friendly way to increase living space while staying within the footprint of your existing property.

Can a kitchenette or bathroom be added to a room in a house without converting it to a JADU or Internal ADU?  Can a kitchenette or bathroom be added to a guest house or pool house without converting it to an ADU?

Bathrooms can typically be added to a house or pool house. If a kitchen (including an efficiency kitchen) is proposed, then it is classified as an ADU and needs to comply with all ADU rules. 

Do “tiny homes” on wheels qualify as an ADU? JADU? What about small manufactured homes (mobile homes or prefabricated units) or efficiency units? Are there any dimensions that are important for qualification?

“Tiny homes” on wheels are not allowed in Town. All housing units must have permanent foundations and connections to utilities. Manufactured homes are allowed through the normal Town process and may be a cost-efficient option for certain sites. Minimum sizes of ADUs and JADUs are regulated only by the Building Code; they can be as small as people want as long as they meet Building Code requirements. 

What is a ministerial review?

A review process which is objective in nature and involves no personal judgment. The reviewing body confirms that all requirements are satisfied before approving a project, and may not consider public comment or impose conditions of approval. An ADU or JADU application which qualifies for ministerial review shall be acted upon within sixty days of the date the town receives a completed application.

What is a discretionary review?

Review of a project against the General Plan, municipal code, and Design Guidelines. The reviewing body exercises judgment in applying policies to a specific project in context and determining whether the required findings for approval can be made. The reviewing body considers public comment and may impose conditions of approval on the project.

Why would a project require a discretionary review?

Typically ADUs do not need a discretionary review, but some of the factors which would trigger one include: the addition of a separate driveway, a property adjacent to a Scenic Corridor, an internal ADU larger than 1,200 sq ft, exceeding height limits, and an attached ADU which causes the main residence to exceed 85% of AMFA, among others.

What is AMFA?

AMFA is the adjusted maximum floor area for a residential parcel, calculated by the Town using the parcel’s size, slope, mapped ground movement potential and mapped flooding potential.

Can an ADU exceed the AMFA limits?

In most cases. You can build a detached ADU up to 800 square feet with a maximum height of 16’ that exceeds your AMFA unless one of the Town’s safety exceptions applies.

If someone is doing an extensive remodel of their home and wants to add an internal ADU, can they exceed the AMFA? Can an attached ADU exceed the AMFA?

No. The AMFA can only be exceeded for new detached ADUs in accordance with State law.

What constitutes a minimum efficiency kitchen?

A space that includes a permanent cooking facility, including a small cooktop (oven not required), a sink, a food preparation counter, and storage cabinets that are a reasonable size. Note that compact all-in-one kitchenette units are readily available from appliance vendors.

Do newly constructed ADUs require solar systems? Fire sprinklers?

Newly constructed ADUs require a solar system under California Building Code requirements. Typically there is an option to put the system on the main house or the ADU. Most newly constructed ADUs have fire sprinklers. Contact the Woodside Fire Protection District for more information.

Will I need to upgrade my electrical panel or convert to sewer?

It depends. Please contact the Town Planning Department about your particular situation.

Will I need to upgrade my electrical panel or convert to sewer?

It depends. Please contact the Town Planning Department about your particular situation.

Will an ADU impact my property taxes?

Yes. If you’re adding new square footage or changing the way a property is used (e.g., converting a pool house or garage to an ADU), the San Mateo County Assessor’s office will add value for the assessable new construction. Only the portion of the property that is newly constructed or completely renovated will be reassessed and the existing home will retain its previously established Proposition 13 base year value. New income-producing properties may be assessed differently than other types of home improvements. Visit www.acgov.org/assessor for more information.

Can I rent my ADU as a short-term rental on AirBnb, VRBO, etc.?

No, the Town of Portola Valley prohibits any rentals less than 30 days. All ADUs that are rented must be rented for 30 consecutive days or more.

Can a room in a house legally be rented without officially converting it to a JADU?  Can a guest house or pool house legally be rented without officially converting it to an ADU?

Yes, but it doesn’t count towards the Town’s affordable housing obligations.

Do I have to live on the property after building an ADU/JADU?

It depends. The Town requirement is for either the main house or the ADU to be owner occupied. There is a special state law in effect that alters the Town requirements. If the ADU is approved between January 1, 2020 and December 31, 2024, then both the ADU and main house may be rented.  Where there is a JADU, either the JADU or the main house must be owner occupied, regardless of when it is built.

Does building an ADU/JADU create an owner occupancy deed restriction?

ADUs approved between January 1, 2020 and December 31, 2024 do not require either the ADU or main building to be owner occupied. JADUs require either the main building or JADU to be owner occupied.  Neither unit, however, requires a deed restriction recorded under current Town regulations.

If I have an appropriate space within my house for an ADU or JADU less than 500 sf, why would I not call it an internal ADU (to avoid having the owner occupancy requirements)? Are there any specific requirements to calling a unit an internal ADU vs a JADU?

It would depend on the configuration of units on your property. If you have a detached ADU, then the internal area would need to be considered a JADU (not an ADU) so that you can have both an ADU and JADU overall. The applicant tells the planning department what they want to call it, and the planning department walks through the implications with them. It may impact future decisions. 

If a resident has an unpermitted accessory structure (e.g., pool or guest house) on their property, what are the requirements to turn it into a permitted ADU?

Through the current process, they need to comply with all current zoning and building codes. An amnesty program is being considered which might provide a lower threshold. 

I’m in an HOA that restricts ADU development. Does state law supersede HOA CC&Rs?

Assembly Bill 670 (2019) and AB 3182 (2020) amended Section 4751, 4740, and 4741 of the Civil Code to preclude common interest developments from prohibiting or unreasonably restricting the construction or use, including the renting or leasing of, an ADU on a lot zoned for single-family residential use. (HCD Handbook 2022)

I live in a Very High Fire Severity Zone and/or have a high steep slope. Can I build an ADU?

You can convert an existing space into an ADU or JADU, as you would not be changing the footprint. For new-construction ADUs, please check with the Town Planning Department, to learn more about the requirements.