Please Advise: ADU Cost Components Breakdown?

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Please Advise: ADU Cost Components Breakdown?

Emil PinlacPro Member
Investor · Sacramento, CA · Member since 2020 · 64 posts · 17 votes

Would anyone be able to give a quick breakdown of the various costs associated with planning and building an ADU in either your backyard, or as a garage-conversion in California? I'm talking about modest-sized JADUs or ADUs in the 400-600 sq. ft. range.

I've been considering building or converting a garage into these units, for a long-term, buy & hold real estate strategy. But I just wasn't sure where to start, or how to properly save/consider the various costs associated with them. 

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Whitney Hill
Contractor · San Diego, CA · Member since 2016 · 88 posts · 100 votes
6y

As a good rule of thumb, figure on $275-325/sqft for all-in ADU project costs…so an 500 sqft 1BR standalone ADU would typically cost around $160K. You can think of costs in two phases… Pre-construction and Construction:

  • Pre-construction costs: $10-15K
  • -Design: if using a stock plan, the design work costs about $5K. If going with a full custom plan (e.g. you have a unique lot layout that will require a customized layout)… closer to $10K, including construction drawings, title 24 energy report & electrical layout, permit processing
  • -Permits: $5K is typically what the total costs to the city will run for an ADU, even with the waived fees
  • Construction costs: $250/sqft + $10K
  • -Building costs: typically $250/sf to start, for vertical building only. This is higher than for single family homes, since the cost is spread out over a much smaller footprint (e.g. still a kitchen+bath, but only 1-2 BRs).
  • -Site work: typically $10K is a good number to start with, which includes preparing the building pad, connecting utilities, plus a small amount of landscape and concrete work.
  • Other costs (not typically required): Additional structural engineering, Civil engineering, Soils engineering


Also, the cost would be around $75K for a standard garage conversion project of about 400 sqft....$8-10K for plans/design/engineering, $3-5K permits/fees, rest construction costs.

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  • Christine Smith
    Member since 2019 · 72 posts · 27 votes
    6y

    Following

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  • Paul DashevskyPro Member
    Investor · Los Angeles · Member since 2020 · 152 posts · 60 votes
    6y

    @Emil Pinlac 

    I have an ADU construction checklist I can send you if you DM or email me.

    1Reply
  • Whitney Hill
    Contractor · San Diego, CA · Member since 2016 · 88 posts · 100 votes
    6y

    As a good rule of thumb, figure on $275-325/sqft for all-in ADU project costs…so an 500 sqft 1BR standalone ADU would typically cost around $160K. You can think of costs in two phases… Pre-construction and Construction:

    • Pre-construction costs: $10-15K
    • -Design: if using a stock plan, the design work costs about $5K. If going with a full custom plan (e.g. you have a unique lot layout that will require a customized layout)… closer to $10K, including construction drawings, title 24 energy report & electrical layout, permit processing
    • -Permits: $5K is typically what the total costs to the city will run for an ADU, even with the waived fees
    • Construction costs: $250/sqft + $10K
    • -Building costs: typically $250/sf to start, for vertical building only. This is higher than for single family homes, since the cost is spread out over a much smaller footprint (e.g. still a kitchen+bath, but only 1-2 BRs).
    • -Site work: typically $10K is a good number to start with, which includes preparing the building pad, connecting utilities, plus a small amount of landscape and concrete work.
    • Other costs (not typically required): Additional structural engineering, Civil engineering, Soils engineering


    Also, the cost would be around $75K for a standard garage conversion project of about 400 sqft....$8-10K for plans/design/engineering, $3-5K permits/fees, rest construction costs.

    5Reply
  • Brian Larson
    Investor · San Jose, CA · Member since 2018 · 313 posts · 230 votes
    6y

    @Emil Pinlac

    Here is a rough breakdown from the Silicon Valley Housing Trust Presentation I went to about 1 year ago.  Obviously, this will be Bay Area prices.  Sacramento should be less.

    (https://housingtrustsv.org/programs/homeowner-programs/accessory-dwelling-unit-program/)

    2Reply
  • Kevin Chen
    Real Estate Consultant · Member since 2020 · 16 posts · 4 votes
    6y

    @Emil Pinlac - we're based on the Bay Area so prices may be a bit lower in Sacramento but we've done a few projects in a similar price range as @Whitney Hill mentions - $150-200K of project costs for ADUs ranging from 500-750 sq ft. With us, the project cost includes in-house design fees, permit expediting, construction costs w/ a licensed GC, and structural/T24 survey consultants. Keep in mind some GCs include finishes & appliances while others don't. The figures above include LG/GE stainless steel appliances, quartz countertops, engineered floors (don't do laminate!), etc. but we're able to get & pass through some discounts at our volume.

    Re: garages, @Whitney Hill is on the mark again - roughly $90K (includes construction & design and excludes permit costs) is reasonable. 

    We're not in Sacramento yet, but feel free to DM me and I'd be glad to chat through your project and see if I can be helpful as a resource.

    2Reply
  • Emil PinlacPro Member
    OP
    Investor · Sacramento, CA · Member since 2020 · 64 posts · 17 votes
    6y

    @Kevin Chen @Brian Larson @Whitney Hill

    You guys are truly awesome. Thank you so much for your detailed responses! 

    I had just a few quick clarification questions in order to dig a little deeper based on the numbers presented above: 

    1) An ADU will inherently include: 1 bedroom, 1 bath, small/mini kitchen, and living room space, correct? When we're talking about square footage between 500-1200 sq. ft. now it just becomes a matter of how big we want each of the spaces to be, right?

    2) Construction Phase: Could you define what you mean by "vertical building" only?

    3) Could you expand on why to do engineered floors vs. laminate? 

    Thank you guys so much. 

    0Reply
  • Liam B.
    Investor · Los Angeles, CA · Member since 2018 · 43 posts · 20 votes
    6y

    If you don't use your garage that much I would just convert the garage to save. Also, plumbing and electrical lines running it could be a big cost depending on your home layout. Is there any plumbing lines by the garage or electrical? If your garage is detached look into adding an addition to the garage. Most garages are 400sqft so adding 200sqft will give you a nice 1 bed 1 bath. How tall is ceiling in the garage? Could do vaulted ceiling which looks nice and adds space to the ADU

    0Reply
  • Whitney Hill
    Contractor · San Diego, CA · Member since 2016 · 88 posts · 100 votes
    6y

    Size... You can fit a lot in 1200sqft... I've seen 3BR/3BA. Typically we'd do a 500 sqft 1BR (bc no engineering review <500 sqft), 750 sqft 2BR (bc no impact fees <750), and a 3BR/2BA at 1200 sqft. So sure, you could have a giant 1BR and we've done that, but you can add additional beds and baths... can't have 2 kitchens though (e.g. you can't make a duplex ADU)

    Vertical building... construction of building itself. Leave out the sitework and plans/permitting etc. This is since that last part varies a lot - like if you had demo or grading or a septic system to put in before you could start building the structure.

    Floors... we typically go for luxury vinyl plank vs either laminate or engineered wood. Imagine @Kevin Chen is talking about laminate being less resilient than engineered, so if same price... would also pick engineered! Echo Kevin's point about what should be included... quartz countertops & appliances applies for what we include as well.

    1Reply
  • Jake Weir
    Real Estate Agent · Sacramento, CA · Member since 2012 · 111 posts · 26 votes
    6y

    @Emil Pinlac The City and County have detailed information on their websites. The City waives some of the fees if the property is in certain areas (downtown, etc). Do you own the property or are planning this into a potential purchase? I've not developed an ADU, but done some of the digging. There are lots of criteria like setbacks and maximum percentage of ADU SF compared to the main building that affect permitting costs or whether the ADU is even allowed.

    https://www.cityofsacramento.org/Community-Development/Resources/Accessory-Dwelling-Units


    https://planning.saccounty.net/Pages/Accessory-Dwelling-Units.aspx



    0Reply
  • Brian C.
    Arcadia, CA · Member since 2020 · 10 posts · 2 votes
    6y
    Originally posted by @Emil Pinlac:

    @Kevin Chen @Brian Larson @Whitney Hill

    You guys are truly awesome. Thank you so much for your detailed responses! 

    I had just a few quick clarification questions in order to dig a little deeper based on the numbers presented above: 

    1) An ADU will inherently include: 1 bedroom, 1 bath, small/mini kitchen, and living room space, correct? When we're talking about square footage between 500-1200 sq. ft. now it just becomes a matter of how big we want each of the spaces to be, right?

    2) Construction Phase: Could you define what you mean by "vertical building" only?

    3) Could you expand on why to do engineered floors vs. laminate? 

    Thank you guys so much. 

    LVP (Luxury Vinyl Planks) is waterproof and easier to replace vs laminate which has a substrate that is not water resistant and would not be applicable in wet areas. 

    0Reply
  • Gaurav Mehta
    New to Real Estate · San Jose, CA · Member since 2017 · 91 posts · 23 votes
    6y

    Anyone knows an architect for ADU who is local in Bay Area.

    0Reply
  • Namit Raisurana
    Investor · San Carlos, CA · Member since 2017 · 37 posts · 17 votes
    6y

    have any of you looked into getting a manufactured home for the adu? since its going to be rental anyways, does it really need to be that high end? there are many adu companies out there who would provide you the model from builder like champion home or clayton home, and then take care of site work - foundation + pulling all utilities. the lowest quote i have recd is for 146k for around 770 sqft. 

    0Reply
  • Gaurav Mehta
    New to Real Estate · San Jose, CA · Member since 2017 · 91 posts · 23 votes
    6y
    Originally posted by @Namit Raisurana:

    have any of you looked into getting a manufactured home for the adu? since its going to be rental anyways, does it really need to be that high end? there are many adu companies out there who would provide you the model from builder like champion home or clayton home, and then take care of site work - foundation + pulling all utilities. the lowest quote i have recd is for 146k for around 770 sqft. 

    It will end up being the same. if you are converting an existing space to an ADU then it might be a lot cheaper.

    0Reply
  • Luis Castellon
    Member since 2018 · 21 posts · 12 votes
    6y

    @Emil Pinlac I've done a handful of ADUs here in Los Angeles area, It usually cost me around 30k to do a straight garage conversion (420-500 square feet)and around 40-50k For a brand new 500 square feet ADU but I do it as owner builder and sub everything out. [Solicitation Removed by Moderators]

    0Reply
  • Rachel S.
    Investor · Los Angeles, CA · Member since 2019 · 127 posts · 63 votes
    6y
    Originally posted by @Luis Castellon:

    @Emil Pinlac I've done a handful of ADUs here in Los Angeles area, It usually cost me around 30k to do a straight garage conversion (420-500 square feet)and around 40-50k For a brand new 500 square feet ADU but I do it as owner builder and sub everything out. If you have any other questions message me and I can try to help you out.

    That's great, a lot lower than I have seen. Are you using a company that builds prefab or an independent contractor?

    0Reply
  • Luis Castellon
    Member since 2018 · 21 posts · 12 votes
    6y

    @Rachel S. No I haven’t done any prefab I get all the permits from the city as Owner Builder, and I sub contract the job and I also manage the project that is how I get to save money on the build. 

    2Reply
  • Rachel S.
    Investor · Los Angeles, CA · Member since 2019 · 127 posts · 63 votes
    6y
    Originally posted by @Luis Castellon:

    @Rachel S. No I haven’t done any prefab I get all the permits from the city as Owner Builder, and I sub contract the job and I also manage the project that is how I get to save money on the build. 

    I may pick your brain at some point...lol 

    160 k for 500 sq ft on land you already own is seriously off-putting!

    0Reply
  • Luis Castellon
    Member since 2018 · 21 posts · 12 votes
    6y

    @Rachel S. I think 160k for 500 square feet ADU is way too much I think, But it also depends on what city you want to build contractors tend to charge more on high end expensive cities. If you have any questions message me I'll try to help you out if I can.

    0Reply
  • Rachel S.
    Investor · Los Angeles, CA · Member since 2019 · 127 posts · 63 votes
    6y
    Originally posted by @Luis Castellon:

    @Rachel S. I think 160k for 500 square feet ADU is way too much I think, But it also depends on what city you want to build contractors tend to charge more on high end expensive cities. If you have any questions message me I'll try to help you out if I can.

    I'm in LA.

    0Reply
  • Brian C.
    Arcadia, CA · Member since 2020 · 10 posts · 2 votes
    6y
    Originally posted by @Luis Castellon:

    @Emil Pinlac I've done a handful of ADUs here in Los Angeles area, It usually cost me around 30k to do a straight garage conversion (420-500 square feet)and around 40-50k For a brand new 500 square feet ADU but I do it as owner builder and sub everything out. [Solicitation Removed by Moderators]

    I can second this, as what I was seeing from the very first few posts coming out to 250-300$ is what it would cost you from a GC w/ markup, but in terms of owner builder it would cost you $140-$150/sf maybe even less if you have the right subs. But I understand not everyone will be able to do that and will need to find a GC to build it out for them and pay them their general conditions, contingencies, and markups.

    0Reply
  • Gaurav Mehta
    New to Real Estate · San Jose, CA · Member since 2017 · 91 posts · 23 votes
    6y

    @Luis Castellon

    When you say brand new ADU for 50K, do you build on top.of garage or in the backyard?

    0Reply
  • Luis Castellon
    Member since 2018 · 21 posts · 12 votes
    6y

    @Gaurav Mehta

    No I’m sorry for the confusion by new I mean ground up single story 500 square feet. 

    0Reply
  • Ellen Pittleman
    Member since 2020 · 1 post · 0 votes
    6y

    @Luis Did you use an architect or buy existing plans?

    0Reply
  • Jim Spatzenfeld
    Investor · NorCal · Member since 2015 · 281 posts · 240 votes
    6y

    A friend of mine added 1200 sqft in SoCal, turning his SFR into a duplex (illegally added the kitchen after inspection). He did it as owner builder and did some work himself. Came out to $75 / sqft including permits etc, but that was 10 years ago.

    0Reply
  • Gaurav Mehta
    New to Real Estate · San Jose, CA · Member since 2017 · 91 posts · 23 votes
    6y
    Originally posted by @Luis Castellon:

    @Gaurav Mehta

    No I’m sorry for the confusion by new I mean ground up single story 500 square feet. 

     How much does foundation and framing cost in that case?

    0Reply
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