Cost of building an ADU in San Jose

Cost of building an ADU in San Jose

fremont, CA · Member since 2016 · 41 posts · 3 votes

I was wondering what will be a cost of building an apartment quality 1000 sq ft. ADU unit (2 bed/2 bath/ 2 story) in the san francisco bay area. any inputs will be appreciated. I am looking for a quote for construction only excluding all the soft costs like architectural,engineering, permit, etc.

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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

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  • Rental Property Investor · San Diego, CA · Member since 2016 · 306 posts · 205 votes
    9y

    @Account Closed in San Jose, the maximum size of an ADU on a lot zoned R1 is 800 sqft and that is only if your lot is larger than 10,000 sqft.

    ≤ 9,000 sq.ft. lot – 600 sq.ft. maximum

    9,001 to 10,000 lot – 650 sq.ft. maximum

    > 10,000 lot – 800 sq.ft. maximum

  • fremont, CA · Member since 2016 · 41 posts · 3 votes
    9y

    @Ariel Smith Thanks for the information on the ADU restrictions in San Jose. Still would be nice to get an estimate roughly how much would be the construction cost for an 800 sq ft unit before I start planning in that direction.

  • Rental Property Investor · San Diego, CA · Member since 2016 · 306 posts · 205 votes
    9y

    @Account Closed no problem! Unfortunately I can't help with the construction quote, but if you put it in a different forum, then someone might be able to answer.

  • Rental Property Investor · San Francisco, CA · Member since 2013 · 1k+ posts · 1k+ votes
    9y

    $250-300 PSF

  • Rental Property Investor · San Jose, CA · Member since 2017 · 39 posts · 13 votes
    8y

    @Account Closed

    For this area, I would plan on $300-$350/sq foot. This includes both design, permits and build.  It can vary a lot based on complexity, materials, and finishes but that should get you started.

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

    We had a panel of architects and someone who's actually gone through the process as a regular home owner at our Meetup back in May. The all-in costs including material, labor, permits, foundations, etc excluding your furnitures is around $120 - 150k. You can find some relevant info here: https://wp.me/p8Uf93-99

  • fremont, CA · Member since 2016 · 41 posts · 3 votes
    8y

    @Jason Hsiao do you have pictures of the in law unit that got done from 120-150k. just want to understand what can be done with this price target.

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

    I don't have any picts myself @Account Closed but if you reach out to the architects that were on the panel - profile info in that post I shared - they should have some. My other friend Adam Mayberry who was not on the panel has some from his IG account - https://www.instagram.com/adamsmayberry/ You can reach out to him as well.

  • 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

  • San Jose, CA · Member since 2017 · 25 posts · 5 votes
    7y

    @Chen Zhou That's a really good timeline. My sister built in Oakland and I think her project took at least a year and a half. Do you mind if I ask what were the costs of your permits & also the build? I'm looking at a detached instead and I might be looking in the ballpark of $300/sf with one of the firms I've talked to. This is also a prefab ADU, not stick built. SJ seems more lax - I would be building in Fremont, so unfortunately may have a longer timeline.

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

    @Laura C.You can do under $250/sf (including architecture) from ground up - let me know if you need a referral. Permit + inspection cost + school/park fees is probably around $40k. Prefab is not as flexible so I'd advice against it unless it has a huge cost advantage.

  • San Jose, CA · Member since 2017 · 25 posts · 5 votes
    7y

    @Chen Zhou $250/sf wouldn't be bad.  Yes, feel free to PM me your contacts.  However, I didn't realize fees would be in the 40Kish range.  Yikes.  

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

    @Chen Zhou, thanks for the information. I am also looking at adding a detached 700 Sq Ft ADU in San Jose/Milpitas area. I would like to know the architects/Engineers & the builders information. So far I got around $300/Sq Ft. Your information will be very helpful. Thanks you so much.

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

    @Basu Ulla - I’m working with @Adam Mayberry to design my ADU in San Jose. He is a wealth of information.

  • Architect · San Jose, CA · Member since 2014 · 90 posts · 57 votes
    7y
  • Rental Property Investor · Santa Clara, CA · Member since 2019 · 160 posts · 156 votes
    7y

    For those of you 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

  • Rental Property Investor · Torrance, CA · Member since 2016 · 263 posts · 132 votes
    7y

    @Chen Zhou

    Congratulations! Your ADU is beautiful! How did you get the cool 3D view? Was there a company that makes those?

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

    @Matthew ForrestYes, it's a company called Matterport. I find it really easy to have 3D visual handy when you are trying to find potential tenants...

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

    ! Great News: On Dec. 17, 2019, the San Jose City Council approved easing ADU requirements to align with new state laws. We are updating our ADU Universal Checklist and website to reflect these changes. Visit the Secondary Unit Ordinance webpage to see the new changes: https://www.sanjoseca.gov/business/development-services-permit-center/accessory-dwelling-units-adus/secondary-unit-ordinance-updates

    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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