Belmont has adopted Ordinance No 2017-1118 which amended the development standards for ADUs.
General Provisions – The following provisions apply to all ADUs:
- There is no minimum lot size.
- The project site is zoned for residential use (Single or Multi-family), including R-1, R-2, R-3, R-4, R-5, Hillside Residential and Open Space (HRO), and residential Planned Developments (PD) Districts.
- There is a single-family dwelling (SFD) on site.
- There is only one ADU permitted on site.
- The ADU cannot be sold separately.
- No Parking is required for the ADU unless it replaces an existing garage, carport or uncovered parking area.
- Neither the ADU nor the SFD may be used for short-term residential rentals.
- Either the SFD or the ADU must be owner-occupied if the home and ADU are occupied by different families.
- An accessory dwelling unit must include no less than the minimum floor area identified for an efficiency unit, as defined in Health and Safety Code Section 17958.1 (currently 150 sq. ft.).
Except as modified by Section 24 and as identified below, a detached ADU must conform to all requirements of the underlying residential zoning district, any applicable overlay district, and all other applicable zoning provisions, including height, setback, floor area ratio, and historic preservation requirements.
- Setbacks.(A) A detached accessory dwelling unit must be located no less than five feet from the primary dwelling unit on site.(B) The minimum side setbacks for a detached ADU is five feet from interior side lot lines and fifteen from street side lot lines of corner lots.(C) On reverse corner lots, a detached ADU may not project beyond the inner line of the front yard required on the adjacent lot to the rear, nor be located less than five feet from the side lot line of such adjacent lot.
(D) The minimum rear yard setback for a detached ADU is five feet.
(E) Notwithstanding subsections (A) through (D), the minimum setbacks for an ADU that is constructed above an existing garage is five feet from the rear and side property lines (including street side corner lots and reverse corner lots).
(A) A one story detached ADU may be up to 15 feet in height.
(B) A detached ADU constructed over a garage or other accessory structure where the ADU would be five feet from the rear or side lot line may be up to 17 feet in height when such unit has a flat roof.
(C) A detached ADU constructed over a garage or other accessory structure where the ADU would be five feet from the rear or side lot line may be up to 20 feet in height when such unit has a pitched roof.
(D) A detached ADU constructed over a garage or other accessory structure where the ADU would meet the side and rear yard setbacks of the underlying zoning district may be up to 20 feet in height when such unit has a flat roof.
(E) A detached ADU constructed over a garage or other accessory structure where the ADU would meet the side and rear yard setbacks of the underlying zoning district may be up to 24 feet in height when such unit has a pitched roof.
- The maximum floor area of a detached ADU is 800 square feet.
- Separate utility connections between the ADU and all utilities, and connection fees/capacity charges may be required, consistent with Government Code Sections 66000 and 66012.
A detached ADU must comply with the following design standards:
a) The ADU must comply with the Residential Design Criteria (RDC) if the new construction includes: 1) a ground floor plate height that exceeds 12 feet or a roof height that exceeds 18 feet (as measured from finished grade); or 2) creates or expands an upper floor.
b) The ADU must be constructed with compatible/complementary facade materials, generally the same color palette, and similar in texture and appearance to the primary dwelling, including but not limited to roofing, siding, windows, and doors.
c) The ADU roof pitch/form must be compatible with the roof pitch/form of the primary dwelling.