Blogging Bayport Alameda

June 24, 2019

In the backyard

Filed under: Alameda — Lauren Do @ 6:04 am

The Planning Board has on its agenda proposed amendments to help make it easier to build accessory dwelling units in Alameda.  It’s gotten marginally better since the first loosening of the rules but still a challenge for most people who are interested in an ADU.

Some history from the staff report:

Prior to 2017, only two Accessory Dwelling Units (ADUs) were approved in Alameda during the previous eight years.  In 2017, the City Council adopted a new ADU Ordinance to bring the City’s ordinance into conformance with state law.  Since then, the City has passed inspections on 20 new ADUs.  While the number of ADUs has grown in the past two years, the ordinance continues to unnecessarily restrict Alameda property owners from adding small more affordable units on their properties.  In particular, the ordinance places restrictions on unit size, requires costly architectural ornamentation, and limits eligibility to current owner occupants.

While 20 units built in two years is better than two units built in eight years, it’s still a very small drop in the bucket to what could be provide a lot of flexibility for property owners and provide more housing units in Alameda.

Staff is proposing the following four amendments:

1. SIZE – allow ADUs to occupy the entire basement area: Currently ADUs are limited to 50% of the floor area of the primary dwelling, up to 1,200 sq. ft.  For example, a 1,000 square foot home can have an ADU of up to a maximum of 500 square feet in size (1,000 x 50% = 500 sq. ft.).  Staff has found the 50% limit to be problematic for many Alameda homeowners wanting to convert their basement into ADUs, because the 50% rule effectively limits the basement conversion to half of the basement area.  The remaining half of the basement must be left unimproved.  In reality, many homeowners end up foregoing the project because construction costs do not justify converting just half of the basement, and this is because the costs for converting a full basement versus half a basement is insubstantial due to economies of scale.  By granting an exception to the 50% rule, homeowners can use an entire basement, instead of half of it, for an ADU.  The proposed amendment would still cap the maximum floor area of the ADU at 1,200 square feet, but this limit will be sufficient to allow homeowners with basements to maximize their use.

I don’t know how many units this would actually create but it sounds totally reasonable.

This next one is the big one, pre-fabricated units could push down the cost of construction considerably and if there could be a list of pre-approved designs that would not require design review or other administrative review costs, that would be a substantial cost savings.

2.  DESIGN AND COSTS – allow Energy-Efficient, Sustainable, Pre-fab/Modular ADUs:  According to an April 2019 article in the San Jose Mercury News, the average cost of construction in the Bay Area is now over $400 per square foot, the highest in the world.  A 600 square-foot ADU could easily cost a homeowner upwards of $240,000.  Homeowners and architects have approached the City inquiring about lower cost pre-fabricated (pre-fab) or modular ADU cottages.  As mass produced products, modular units tend to be less costly than building a new building from raw materials.  Pre-fab units can achieve up to 20% savings, although many variables, such as interior furnishings and other owner options factor into the final costs.  Pre-fab units, because they are manufactured as a building system, also tend to be energy efficient by design and use sustainable building materials.  Pre-fab units are currently not permitted under the ADU ordinance, because the ordinance requires all detached ADUs to match architectural detailing on the primary dwelling, including shape, roof form, and any decorative moldings.  The current design requirement creates extra cost and establishes a barrier to sustainable building solutions.  Staff recommends allowing pre-fab units to be located in back and side yards where they are not visible from the public street.  The proposed amendment would still require ADUs in the front yard or on corner lots where they are visible from the public street to match the architectural details on the primary dwelling.

This next amendment is also a considerable change as well:

3. ELIGIBILITY RESTRICTIONS – remove owner-occupant requirement:  The ordinance currently requires an applicant for an ADU to be the current owner-occupant.  In practice, applicants are asked to provide copies of recent utility bills and property tax statements as proof of their owner-occupant status.  However, owner occupant status can only be verified at the time of application, as there is no effective means to monitor or enforce owner-occupant status after an ADU permit has been issued. Further, the City has no mechanism or valid policy objectives to require removal of the unit, if the property owner chooses to relocate.  Verification of owner-occupant status also becomes problematic when properties are held under a family trust or other forms of ownership.  Staff recommends deleting the owner-occupant requirement from the ordinance.

These next two also make sense, but it’s not clear why 6000 sq ft is the magic number for allowing for expanded capacity.   It seems if we’re looking for ways to increase the number of units that exist we shouldn’t be tied to some subjective x number of units per square feet.

4. EXPAND CAPACITY – allow up to two (2) ADUs on large lots: On April 16, 2019, the City Council expressed interest in expanding capacity for ADUs, including allowing more than one ADU on a lot.  Staff recommends up to two ADUs be permitted on large lots that are 6,000 square feet in size and greater, and permitting such lots to have one attached and one detached ADU.  The cumulative size for both ADUs would be capped at 1,200 square feet, which is the current maximum for a single ADU.

5. EXPAND CAPACITY – allow an ADU on large properties with an existing duplex. Currently, ADU’s are allowed only on properties with proposed or existing single family homes.  Alameda has a number of large (6,000 square foot +) properties with existing duplex buildings that could accommodate an ADU in a rear garage or with a modular unit in the rear yard.  Staff recommends allowing addition of an ADU on properties with existing duplex units, provided that no more than two units are included in any single structure and provided that the parcel is at least 6,000 square feet in size.


  1. Its not just about “design.” If the City was serious about ADUs as a solution to the housing crisis, then they’d look to reduce the actual overall costs, by easing up on rent control restrictions which have capped rent increases, elminated no cause evictions, and then requiring landlords to pay market rate relocation fees. Instead the progressive city council has blown through economic warnings that rent control depresses property values over time and eliminates market incentives to improve the property. A Mom and Pop landlord needs to be able to get a building loan, pay high construction costs, and then see a reasonable return on their investment over a short period of time. It can’t be done currently. Solution: Subsidize a loan, guarantee a reasonable return, speed up the permit process, waive the fees. Otherwise, this is just for corporate property owners.

    The market figures- “2” actual ADUs built in 8 years don’t lie.

    Comment by Nowyouknow — June 24, 2019 @ 7:18 am

    • People weren’t building ADUs in those last 8 years because it was prohibitively expensive and difficult to do so. It has nothing to do with rent regulations. In those eight years it was a free for all in the rental property market. Try again.

      Comment by Lauren Do — June 24, 2019 @ 8:29 am

      • Both are true.

        Regulations have been the first problem. They’ve most definitely increased costs and discouraged construction. Rent control, though, and its attendant takings of property are also a very strong disincentive. Consider the relocation ransom now enshrined in law. Who on earth would accept a tenant literally in their back yard that they couldn’t get rid of without a 5 figure hit?

        Comment by dave — June 24, 2019 @ 8:50 am

        • you seem to forget that the landlord is getting a three figure rent every month the equals a big five figure total for each year.

          Comment by trumpisnotmypresident — June 24, 2019 @ 6:01 pm

        • Have you ever had a job where you were forced to cough up a year’s pay to quit?
          Would you spend ~200K for that privilege?

          How would you feel about having to cough up a late model used car to clear an obnoxious or threatening tenant out of your (literal) back yard?

          Very few homeowners will rent ADU’s on the general market for these reasons. The ones that do get built will likely end up housing relatives or being used as offices, etc.

          Comment by dave — June 24, 2019 @ 7:54 pm

  2. Can someone who owns in an HOA development (i.e. one with an active HOA), with plans to build an ADU that otherwise qualifies under the current city ordinance, or under any of the proposed changes to it, build it as of right (as under the city ordinance) or must she/he seek HOA approval? Have any ADUs been built in active HOA developments? I assume that if the City Council found that the housing crisis is severe enough, it could change the ADU ordinance to remove any power of an HOA to block a proposed ADU which otherwise meets the guidelines of the city ordinance in terms of sq footage, etc.

    Comment by MP — June 24, 2019 @ 7:23 am

    • I think the law has to explicitly override HOA CC&R rules. Like the clothesline legislation.

      Comment by Lauren Do — June 24, 2019 @ 8:27 am

      • I think that’s right, but which law? Can a city override HOA rules, or does state law preempt cities from doing so, such that state law would have to be changed to either directly override HOA rules, or at least allow cities to do so? Interesting questions, given the total space occupied by HOA developments.

        Comment by MP — June 24, 2019 @ 9:18 am

RSS feed for comments on this post.

Sorry, the comment form is closed at this time.

Blog at

%d bloggers like this: