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Santa Monica Forward issues recommendations on zoning for Accessory Dwelling Units


That, if the City Council chooses to count any Accessory Dwelling Unit square footage toward lot coverage in R1 Districts,  this square footage shall be the difference between 800 square feet and the total square footage of the proposed ADU. (As it now stands the R1 Interim Zoning Ordinance exempts any ADU square footage from counting toward lot coverage.)


There is an Interim Zoning Ordinance (IZO) in effect that re-defines development standards for the construction of or additions to single family houses in R1 Districts.  These new interim standards are:

  1. The height of any new single family residence shall not exceed 28 feet.  This brings the area north of Montana into consistency with all other R1 districts in the city.

  2. The maximum lot coverage for a new houses or add-on to an existing house shall not exceed 30% for the first floor and 20% for the second floor, bringing the total allowable lot coverage to 50%.  This reduces the pre-existing lot coverage maximum of 35% for the first floor and 28% for the second floor, or 63% for the entire site. Maximum lot coverage for one-storey houses remains at 50%.


Permanent amendment of the ZO to revise development standards for R1 Districts is expected to occur in late 2018.


State Law (AB2299-Bloom) requires local jurisdictions to accommodate the development of ADU’s.  Its major provisions are:

  1. An ADU can be up to 1,200 square feet but shall not exceed the square footage of the primary residence by more than 50%.

  2. Relaxed parking requirements specify that parking for an ADU need not be provided if it is within a certain distance of public transportation, which is all of Santa Monica.

  3. Replacement parking for the primary residence need not be covered and can consist of tandem parking in the driveway.

  4. ADU approvals shall be ministerial.


State Law also defines an ADU as either attached to the primary residence or a free standing structure.


The Planning Commission has recommended amendment of the ZO to incorporate all the provisions of AB2299.  Previously the ZO had included ADU requirements in the section relating to Accessory Structures, which cannot exceed 650 SF.  ADU’s will now have its own ZO section. The PC has also set the maximum square footage for an ADU at 1,200SF. The City Attorney believes this is necessary for compliance with AB2299.



When the R1 IZO was adopted, the supporters were fine with exempting ADU square footage from calculation of lot coverage.  They assumed that the maximum size for an ADU would be what is currently in the Code, i.e. 650 square feet. That square footage has been increased to 1,200 square feet by the Planning Commission per directions from the City Attorney.

The IZO supporters are very concerned that this increase will undermine the anti-mansionization effort by allowing the construction of oversized homes that attach a 1,200 SF ADU to the new house.  Attached ADU’s must have separate entrances, a bathroom and kitchen and a wall separating it from the primary residence. This will be very difficult if not impossible to enforce.


A compromise has been reached (I think) with a few members of NOMA to require that any ADU square footage above 800 SF be counted toward lot coverage.  I support this compromise for several reasons:

  1. It will discourage the new development of oversized houses.

  2. It will incentivize the construction of ADU’s on existing lots with primary residences of 1,600 SF or less, hopefully discouraging their replacement with new, larger houses.  (Sunset Park especially) This is because of the State restriction that ADU’s shall be no more than 50% the size of the primary residence.

  3. 800 SF is a perfectly adequate size for a 2-bedroom ADU.  This is actually the square footage the PC was proposing before the 1,200 SF issue arose.



This recommendation furthers the following SMF priorities:

  1. Increase the supply of affordable housing.

  2. Facilitate aging in place options.

  3. Protect economic and social diversity.

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