Building an ADU in San Jose

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Investor · Pasadena, CA · Member since 2015 · 269 posts · 189 votes
8y

The assessed value of your ADU should be close to the cost of building it, or replacement cost. Your basis for land and improvement should stay the same. "Fair market value" is just a fancy way of saying what another person is willing to pay for it. With the high construction costs nowadays it's hard to add that much value, plus ADU's don't sell at the same $/sqft as the regular house, and there's not a steady readily available comparable properties to base valuation so the easiest method is replacement cost.

I hosted a Meetup and wrote about ADU's on my website. I have a few architect friends that have gone through the process in multiple cities. It is definitely a hot (and evolving) topic so thanks to @Wayne Brady for creating a thread. If you have other questions or need referrals shoot me note!

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  • Member since 2018 · 2 posts · 1 vote
    8y

    Thanks for starting this thread. If a detatched ADU is built in the backyard, it would need to have a new 100 Amp electrical subpanel right from the main electrical meter installed by the utility company. Can the electrical conduits/wiring for the ADU be run under the primary house's crawl space up until the house's facade facing the ADU and finally underground for the remaining bit? Is that allowed as per the electrical codes? If not, I'll need to trench all the way from the electric panel in front yard which is going to cost a lot, since there's concrete paving all through.

  • San Jose, CA · Member since 2018 · 1 post · 0 votes
    8y

    Hello,

    We are thinking about building an ADU behind our house in downtown San Jose. I am allowed to build a studio or a 1 bedroom ADU up to 700 sq ft. How does an ADU affect my current property tax? This is the information I found in the city's website:

    "Will my property taxes increase if I build an ADU?

    Yes. Under the rules of Prop. 13, the Office of the County Assessor appraises new construction at fair market value when the improvements are complete, and the value of the new construction is added to the total assessed value of the property."

    How is this calculated? Will the existing assessed value of the land and improvements stay the same and just the new improvements added? If so, What is the fair market value of a 1 bedroom or a studio in downtown San Jose? 

    Thank you very much,

    Marie

  • Investor · Pasadena, CA · Member since 2015 · 269 posts · 189 votes
    8y

    The assessed value of your ADU should be close to the cost of building it, or replacement cost. Your basis for land and improvement should stay the same. "Fair market value" is just a fancy way of saying what another person is willing to pay for it. With the high construction costs nowadays it's hard to add that much value, plus ADU's don't sell at the same $/sqft as the regular house, and there's not a steady readily available comparable properties to base valuation so the easiest method is replacement cost.

    I hosted a Meetup and wrote about ADU's on my website. I have a few architect friends that have gone through the process in multiple cities. It is definitely a hot (and evolving) topic so thanks to @Wayne Brady for creating a thread. If you have other questions or need referrals shoot me note!

  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    7y

    Hello everyone, I recently got permit approval in SJ (Willow Glen) for a 630 sqft attached ADU + 170 sqft addition to the existing unit. I'm happy to share my experience working with architect, the city, and contractors here. It took me about 4 months to get my permit and now I'm 3 months away from completion of the construction. Let me know if you have any specific questions.

    I do want to point out that starting from July 2018, owners now can rent out both units without living in the property. With more relaxed rules from July 2018, it makes a lot more economic sense to invest into building an ADU: http://www.sanjoseca.gov/DocumentCenter/View/78534

  • Member since 2019 · 2 posts · 0 votes
    7y

    Hi Chen,

    Sent you a message.

  • Member since 2018 · 20 posts · 7 votes
    7y

    I'm also doing an adu.  Mine is a garage conversion, which is being converted to 350 sq feet of living space.  After looking back, my regret is not taking advantage of the maximum allowed sq footage of 800 sq feet.  I wish I could have expanded the garage to an 800 sq feet 2 bed 1 bath.  If you are going to do an adu, take advantage of the maximum allowed sq footage.  A challenge I'm currently facing is the sewer line going from adu to main sewer line.  It's so far away that we are having a tough time making it work.  

  • Investor · Menlo park · Member since 2016 · 3 posts · 0 votes
    7y

    I am having a 375 sq ft garage. Now I have a option to connvert it to ADU or master suite. I am not sure it is better hold the title as Duplex or SFH . Pls advice!!!

    Besides, add addition to 800sq ft like Joo said, the cost is super high. Just convert the garage already cost $150k. is it worhty to put addition? 

    I will need to let my architect know my decision. Pls help!!! 

  • Brian LarsonPro Member
    Investor · San Jose, CA · Member since 2018 · 313 posts · 230 votes
    7y

    @Holly Collins - I think the ADU question depends on where you live. For instance, if you live in an urban core with a high walkscore, you will probably see a good return on investment because the new space will be in high demand to rent and purchase. However, if you are a long ways from public transit, shopping, and restaurants, the unit will rent for far less and be less desirable for investment purchasing.

  • Investor · Menlo park · Member since 2016 · 3 posts · 0 votes
    7y

    Brian, Sorry that I did not state my question clearly. The property located in Peninsula with attached garage.  Garage conversion is common there ( however, in certain city, it does lower property value) .  

    My question is , either holding the house as duplex with 3 bed 1 bath & one ADU or 4 bed 2 bath house. ADU supposes has no access to the main house ( unverified) .

    Which one is better in your opinion? 

  • Brian LarsonPro Member
    Investor · San Jose, CA · Member since 2018 · 313 posts · 230 votes
    7y

    @Holly Collins - these are 2 different value propositions here.

    1. cashflow (aka rent)

    2. resale value

    Again, I think this depends on what your personal real estate goals are and specifically where the property is located on the peninsula.

    I personally prefer cashflow value because I think it will far out-weigh any negatives when you go to sell in a few decades.

  • Investor · Menlo park · Member since 2016 · 3 posts · 0 votes
    7y

    One point I would like to confirm. Change a garage to ADU , that will change a SFH title to duplex title in santa clara county?

    Thanks ! 

  • Architect · San Jose, CA · Member since 2014 · 90 posts · 57 votes
    7y

    No. its a SFH with an accessory dwelling unit. A duplex is different . (also it really depends on HOW you market the sale)

  • Member since 2019 · 1 post · 0 votes
    7y

    Hello Joo, 

    Regarding your sewer line it sound like you need a mechanical sewer system. My friend had the same issue and we found a construction company in San Jose who is knowledgeable and fixed the problem. 

  • San Jose, CA · Member since 2016 · 1 post · 0 votes
    7y

    Chen ... sent you a message as well. :)

  • Member since 2019 · 1 post · 0 votes
    7y

    I see on https://actonadu.com/learn-about-adus/adu-regulations-by-city/san-jose-ca-adu-regulations can have only 1 bath.

    Is it allowed to have second one as 0.5 (is it still considered bath)? This is for adding 800 sqft unit. please share your experience.

  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    7y

    For those of you who're interested, I completed my ADU project and you can see the 3D visualization of my place here:
    https://my.matterport.com/models/hRAxQheq93H?section=media&mediasection=showcase

  • Investor · Bay Area, CA · Member since 2017 · 85 posts · 35 votes
    7y

    @Chen Zhou, thanks for sharing the picture. Beautiful unit. I am in process of building a 700 sf ADU in San Jose 95126 area. I have been told I need to pay Parkland fee $4850. Is it reasonable in your experience? Apparently there is no guideline in public on how the parkland fee charges for ADU. I haven't figured out how much is the school fee. My contractor asked me to go to the unified school district and pay whatever they ask for.

  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    7y

    @Jim G.$4850 sounds about right...yeah, the amount is pretty much determined by the city...so just pay them so that you get your permit as soon as you can.

  • Investor · Bay Area, CA · Member since 2017 · 85 posts · 35 votes
    7y

    thanks.  Quite a lot of fee.

  • Architect · San Jose, CA · Member since 2014 · 90 posts · 57 votes
    7y

    Jim, we should have worked with you on this, we would have let you know WAY in advance that these fees are coming... you can see the Ordinance here:

    https://www.sanjoseca.gov/DocumentCenter/View/74864

    School fees for anything over 500 square feet, think its $3.40/sf, in your district

  • Member since 2019 · 7k+ posts · 4k+ votes
    6y

    Hi Adam, Is the school fee to build ADU that you mention a one time fee or annual fee ?

    Thanks

  • Rental Property Investor · Long Beach, CA · Member since 2019 · 145 posts · 49 votes
    6y

    Developer fees such as this one are going away Jan 1 2020 for ADU's under 500sf, and reduced fees for those over 500sf. Sounds like you're stuck with them-ouch! I'll save $5k in developer fees by waiting but will have yo solar PV the ADU;maybe do the sfr at the same time.

  • Developer · Sacramento, CA · Member since 2016 · 464 posts · 143 votes
    6y

    @Chen Zhou how did the final product end up looking? Share pics

  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    6y

    @Pavan Sandhu Plz see the pictures and 3D visual under my profile:)

  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    6y

    Finally here! San Jose 2019 ADU ORDINANCE CHANGES!

    The City Council voted on Dec. 17, 2019 to update San Jose's zoning code pertaining to ADUs to align with new California State laws that go into effect on Jan. 1, 2020. San Jose's zoning code changes for ADUs are effective immediately. The table below shows the prior regulations and the newly approved regulations.

    ITEMPRIOR REGULATION (BEFORE DEC. 17, 2019)NEW REGULATIONS THAT ALIGN WITH CALIFORNIA STATE LAWS
    Effective DateCity Council approved the regulations below on July 27, 2018 with subsequent updates approved on May 23, 2019; June 25, 2019; and November 19, 2019.On December 17, 2019, City Council approved the following changes, effective immediately upon their vote on Dec. 17, 2019.
    Zoning District

    ADUs are allowed:

    • In R-1, R-2, and R-M zoning districts on lots that have one single-family residence.

    • In Planned Development (PD) districts that are subject to R-1 standards and uses OR where ADUs are not expressly prohibited.

    • In a low-density cluster development if it conforms to development standards of the R-1 zoning district, and the development and use standards of the low-density cluster permit.

    ADUs are allowed:

    • In R-1, R-2, and R-M zoning districts on lots that have one single-family residence.

    � On lots with a single-family residence In Planned Development (PD) districts that are subject to R-1 standards and uses OR the ADU conforms to the development and use standards of the PD district.

    • On any lot with an existing single-family dwelling unit, where regardless of zoning, the lot has any of the following General Plan Land Use/Transportation designations:

    - Residential Neighborhood

    - Mixed-Use Neighborhood

    - Urban Village or Urban Residential

    - Transit Residential or Rural Residential

    - Downtown

    - Mixed-Use Commercial

    • On two-family (duplex) lots and on multifamily properties

    • In a low-density cluster development if it conforms to development standards of the R-1 zoning district, and the development and use standards of the low-density cluster permit.

    Minimum Lot Size3,000 square feetNo minimum lot size
    Minimum Setbacks from Rear and Side Property Lines0 feet for 1-story conversions and new construction.

    5 feet for second-story ADUs constructed above a garage or accessory structure.
    0 feet for 1-story conversions and new construction.

    4 feet for second-story ADUs constructed above a garage or accessory structure

    4 feet minimum rear and side setbacks required for detached ADU in multifamily developments.
    Maximum Height

    For detached ADUs:

    Single story – 18 feet maximum
    Second story – 24 feet maximum

    Attached ADUs are subject to the height limits of the main home.

    Single-family properties - No change in height requirements.

    Multifamily properties - 16 feet maximum height for detached ADUs.

    Rear Yard CoverageArea covered by the ADU, accessory buildings, and accessory structures, except pools, shall not exceed forty percent (40%) of the rear yard.Area covered shall not exceed forty percent (40%) of the rear yard or up to 800 square feet, whichever is greater.
    Detached ADU Allowed Locations

    Rear yard only, at least 6 feet away from primary dwelling.

    May be attached to a detached garage or other existing accessory structure.

    Must meet minimum setbacks for an accessory building in accordance with Section 20.30.500.

    No changes except that ADUs that exceed forty percent (40%) of the rear yard must maintain minimum 4 foot side and rear setbacks. One-foot overhang for eaves would be allowed.
    ADU Size (in sf)
    LOT SIZE (SF)ADU MAXIMUM SIZE (SF)
    3,000 - 5,444600
    5,445 - 9,000700
    9,001 - 10,000800
    10,001 - Up900
    LOT SIZE (SF)ADU MAXIMUM SIZE (SF)
    Up to 90001,000
    9,000 and greater
    1,200
    Number of Bedrooms and BathroomsTwo bedrooms allowed on lots with an area greater than 9,000 square feet, and only one bathroom.Up to two bedrooms and two bathrooms allowed for all units.
    Attached ADU Maximum Floor AreaMay not exceed 50% of the existing or proposed primary dwelling living area.May not exceed 50% of the existing or proposed primary dwelling living area or 800 square feet, whichever is greater.
    Design StandardsVisual compatibility with existing primary dwelling is required.No design standards, except new simplified standards for attached ADU units for historic buildings listed in the Historic Resources Inventory.
    Parking requirementsAn ADU requires 1 space unless the property qualifies for an exemption under State law—see the parking requirements.

    If a garage has been converted, the main dwelling parking space must be replaced, as uncovered or in front or side setback areas. Parking spaces may be configured on-site per state law.
    No change in parking requirements for the ADU.

    Replacement parking for garages and carports converted to ADUs will not be required.
    Junior ADU
    (JADU)
    Not allowed.Allow JADU up to 500 square feet within the existing walls of a single-family home. Must include at least an efficiency kitchen. May share a bathroom with the primary unit. Owner-occupancy and deed restriction will be required, subject to State law regulations.
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