Backyard Cottages & ADUs

Related Pages: Building Permits ... Prefab Houses

Parent Q&A

Architect to help plan an ADU May 6, 2020 (7 responses below)
Experience with pre-fab ADU Oct 9, 2019 (1 responses below)
ADU Project -- Contractor Selection and Negotiations Jul 5, 2019 (4 responses below)
Tax implications of building an ADU in Berkeley Oct 9, 2018 (6 responses below)
Prefab for ADU? Sep 20, 2018 (1 responses below)
Converted Horse Trailer in Back Yard in Berkeley? Sep 6, 2018 (1 responses below)
Accessory Dwelling Unit designers/architects Aug 12, 2018 (8 responses below)
Small shed in backyard, now Berkeley wants to call it habitable Dec 6, 2017 (4 responses below)
Pre-fab in law Jul 19, 2017 (1 responses below)
  • Architect to help plan an ADU

    (7 replies)

    We are looking to build an ADU on our property. We have a license contractor and have an idea of how it would look, but would like to hire an architect to draw up plans only.

    Can anyone recommend someone who could do this?

    I can recommend Jay Castle of Meshwork Planning and Design.  We are in Berkeley, working on ADU, and have hired Jay.  He's been a great communicator (even during quarantine), understands Berkeley codes, etc., and very open to collaboration with homeowners. www.mshwrk.org

    We used the best architect for our ADU. He was professional, super reasonable and super experienced. He has done multiple ADU’s in the east bay already so it was helpful with someone who had experience and didn’t look clueless. Highly recommend. 
    his website is jbparch.com and he is located in Berkeley. 
     

    good luck! 

    I have worked with Erick from Innovative Construction & Design before and highly recommend him for your architectural needs. You may reach him at 510-289-5516 or email: archdrafter [at] gmail.com. Good luck on your project! You can let him know Elizabeth from El Cerrito referred you. 

  • Experience with pre-fab ADU

    (1 reply)

    We are considering "building" a pre-fab ADU in Berkeley and would love to hear from anyone who has done it. What are the pros (other than cheaper and speedier) and cons? Anyone have experience navigating the permitting process in Berkeley?

    Thank you!

    RE: Experience with pre-fab ADU ()

    I serve on the East Bay ADU Task Force and Nov. 9th is both a date to tour ADUs built in the East Bay (10am-1pm) along with an afternoon workshop at the Fruitvale Library. At first glance pre fab ADUs seem like a bargain and time saver. If you have a large flat lot with easy accessibility it may be an option. Trouble is most of us don't. SO a panelized prefab has a better chance of being able to get moved into a back yard than a fully built one.The cost of the approved foundation & utility connections are a significant portion of the expense. As of Jan 2020 you would need to be certain that the pre fab ADU meets NET Zero construction standards as well.   A number of builders explored pre fabs early on but walked away from them as the confines and shapes of our yards differ too greatly to make the same ADU work.  Overall the savings has not proven to be significant so best to go with something designed for your specific circumstance.  

    Best to start with imagining the various uses over the course of the next decade as ADUs are truly an amazing flexible use space for extended family, aging individuals (ADA friendly) , guest space, close friends, etc that can also provide significant income should this be a desired outcome.  Governor Newsom also just signed into law the ability to build 16ft high so now additional sleeping lofts can provide extra space. Hope that helps!  Rolf 510.540-1111

  • Dear community! I am about to embark on a basement ADU and attic development project that is going to be quite substantial in cost and complexities. Naturally, I would like to keep costs down. I am looking to learn from your experiences around sourcing and project management for this sort of undertakings.

    For example:

    • Searching and identifying (short listing) contractors -- Where did you search, and how did you go about evaluating qualifications to meet the needs of your project? Did you send out a questioner to contractors?
    • Negotiations -- Requesting / receiving bids and cost negotiating – what was your process? How many proposals did you solicit? How did you compare and analyzed the bids? Did you negotiate the cost? Why or why not? What was your approach / strategy? What was the contractor/s reaction (willing or unwilling to negotiate)? What were the biggest challenges and what were the end results of the negotiations (lowered by x%)?
    • Contracts and timelines – Did you negotiate the terms and timelines? Did you write a formal contract? Did you consult with a legal professional, used a template, or just worked with the documents provided by the contractor? In retrospect, do you feel a more binding/stronger contract could have spared you some headaches?
    • If you chose not to negotiate (costs and/or terms), what drove that decision and what were your concerns (harm future relationships, uncomfortable negotiating, no time, stressful, lack of expertise, lack of resources and tools, other)?
    • Project management – did you hire someone to manage the project? Did you do it yourself? What drove either decision? Are there any online tools you can recommend? What were your biggest lessons-learned?
    • At the end, are you satisfied with your process and the results of your project management and negotiations approach? Did you enjoy it and would you do it again? Why or why not? Did you use any online tools that you can recommend? If you had to do it over again, what would you change?
    • In general, where were your biggest challenges, and what would you do different next time? What tips and advice can you share.

    Any and all advise, tips and insights you are willing to share are GREATLY Appreciated!

    Thanks! Nervous First Timer

    Be very careful.  We went through this whole similar experience about this time last year.  Of course costs are always a concern, but what really put the kibosh on our project was the various and byzantine permitting process from the City of Berkeley.  They were in the process of changing their guidelines/etc., and each contractor we spoke to made it sound WAY TOO EASY or WAY TO DIFFICULT to navigate the process, which, apparently, could be costly AND THEN the application for the ADU could be rejected...It simply wasn't worth the aggravation.  Furthermore, in seeking someone to work with, we were disappointed by Design firms, building firms, and Design/build firms, which we thought would really offer the best option-- it turns out that even the Design/Build people were subcontracting out, and we were paying extra administrative fees right and left.  We finally decided it was NOT worth our while (or sanity) to continue this project.  Even professionals who came to us via friends' referrals, ended up being unacceptable. : (

    On March 9, 2019 at the Rockridge Library, we attended ADUs in Oakland presentation. 

    The Oakland Rent Board, Oakland Permit Department, City of Oakland representative plus two private facilitators (Loni Gray and one for Oakland and the other, for Berkeley [I believe]) and contractors, lender and architect who are familiar with the ADU process. 

    After this 2 hour meeting, our family will be making appointments with architects and contractors who have done this sort of work to get estimates - basement, small cottage or modular?   We will also make multiple trips to Oakland and Berkeley to find out what the permitting process is and whether or not our ADU will be rent controlled [we'd like to rent it out until we actually need to use it]  Loni Gray led the ADU Seminar last November and intends to have more -- www.lonigray.com/events  On March 25, Loni and her group held an ADUs in Berkeley presentation.  The name of Loni Gray's group is ADU Task Force.  They are a volunteer organization, but well informed.  

    I am not going to be able to answer all those questions, but I will provide my thoughts/opinions on a few. I asked friends and neighbors for suggestions. If I saw a contractor in the neighborhood, I asked for his/her business card. Get at least three bids. The lowest is not necessarily the best choice. Contractors are very busy; the good ones are booked out several years. You are probably just going to have to accept any bid they provide and be thankful you found someone to do the job. No negotiations. Whether to manage or not depends on your comfort level and your knowledge. Can't give advice on that. But no matter what, you have to keep an eye on the job and make sure that the work is done to your specs. Contractors and subs do stupid stuff to cut corners. Watch out! I love using the space after the project is done. I enjoy it everyday. So, yes, I would do it again. Be aware, that some contractors and subs will take the job and start on time, but they are working three jobs, so are only on yours part-time. Very frustrating! Also, don't pay too much upfront. There are laws about that. Google it. Some contractors take the money and run. 

  • Does anyone know whether building an ADU in Berkeley triggers a re-appraisal of the home/consequent tax increase? To the best of my googling abilities it appears the answer is "no" and it seems like not many people would build one if it did, but I would love some corroborating information! Thanks!

    I'm curious what the other replies are. Last time we pulled a permit for a kitchen remodel, I got a questionare from the Assessor about the improvements. I would think building an ADU would least require the value of the ADU is added to your assessment. 

    https://www.acgov.org/assessor/about_property_assessment/supplemental-as... (<- note that New Construction triggers something, but did the ADU ordinance exclude supplemental assessments?)

    This is what I was suggesting - phrased better from a Santa Cruz guide to ADUs

    " The base value of the land and existing improvements will remain unchanged, and an increment
    representing the change in property value because of the new ADU will be added via
    a supplemental assessment. (See your property tax bill for information on the current
    assessed value of your property.)"

    I built a 1BR/1BA ADU in Oakland (Alameda County is responsible for assessments, so your experience in Berkeley should be similar) and had my property assessment increase by about $125k.  The ADU replaced the detached garage that had been on the site (same square footage) and was done with permits, which triggered the county sending me a form to describe the project.  I spoke with the assessor's office after receiving the increase, and the person handling my file stated that they use a formula to determine the increased value of the property and that my increase was consistent with adding an additional bedroom and bathroom.  Considering the cost of building the ADU and my perception of the ADU's effect on the value of my property, it seemed like a fair assessment and I didn't challenge it.  Prop. 13 limits the county's ability to reassess, so they are not allowed to undertake a full re-appraisal of the home just because you build an ADU.

  • Prefab for ADU?

    (1 reply)

    We’d like to build an ADU in our yard in Berkeley as economical as possible. We spoke to an architect and by her rough estimate, we could no where near approach paying for it.  But I’ve read the archives and it sounds like a few people have opted to do a prefab with a contractors help as a more affordable option.  Has anyone had experience doing this and if so could you give me some details on which prefab you used, which contractor, the budget, and how you navigated the permitting process in Berkeley?  I understand they are making it easier but after speaking with the architect the process still sounded pretty involved and complicated.  

    RE: Prefab for ADU? ()

    Both connect homes and plant prefab are good prefab options. 

  • Hello,

    I'm new to BPN and have a question to ask about parking a converted horse trailer in my back yard.

    I live in Berkeley and am a mum to three kids, and have a cousin's trailer I would love to use in the backyard for a work studio.

    There is no plumbing or electricity (although I could hook it up to our house via an extension cord) and the trailer is 6 ft wide, 19 ft long and 10 ft high.

    Does anyone know about what rules and permits there are for Berkeley on this matter? 

    I've looked on the city website and can't seem to make much sense out of it, am wondering if anyone has experience with this sort of thing that they can share?

    Thanks for your time

    A quick google search shows: 

    Any structure greater than 120 square feet requires a building permit. Accessory structures, including storage sheds, workshops, gazebos, cabanas, garages, carports, wheelchair ramps and similar structures, may be exempted from building permit requirements if the structure does not exceed a floor area of 120 square feet and is not more than one story.

    Even though a building permit may not be required, all structures must meet zoning requirements for use, placement on the parcel, height and size, and building code requirements.  If the structure meets all zoning requirements no zoning permit is required. If a zoning permit is required, talk to a planner at the Permit Service Center or call 981-7410.

  • We are interested in turning our old shed into a living space for a family member. We are looking for an architect who has strong experience with accessory dwelling units (ADUs). If the firm is connected with a construction team, even better. Please let us know if you have any suggestions. Thanks!

    We met with HDR Remodeling and really liked them. 

    However, we didn't end up going through with them because we decided to go another route with our ADU.

    Hi, I highly recommend Levitch Associates. They are a family company based out of Berkeley since the early 1960s. They are a design/build company so they can do design and construction or one or the other. They do beautiful work with meticulous attention to detail. I'm happy to talk about them in more detail, please feel free to contact me.

    I am about to break ground on an ADU in Oakland. I have been using Nathaniel Muhler as my architect, and I would recommend him. (510)295-7092 We are pleased with the design. He has done a few ADUs, I believe. It's a long and complicated process, and he has been helpful navigating all the ins and outs with the city. Good luck!

  • We built a shed with a deck off one corner in our yard last year under the requirements for appropriate shed size (under 120 Sq foot). We did not get it permitted because the code in Berkeley says if it is under that size and under 12 foot average height, you do not need to permit it. The shed was then painted with some windows and a large door. Now the city of Berkeley says we can't have a shed be "nonhabitable" if it has windows and a deck. They are considering it "habitable" because of this and want a building permit. There is nothing in the code that says this (if it has a deck or windows it is considered habitable) ANYWHERE. literally nothing. the shed is exactly that, something where our crap is stored, no one sleeps or stays in there, we do not rent it out, we do not spend time in it. But the city wants it permitted as a "habitable" structure because it looks nice and because there is a deck with windows. It is bogus. When we built it we asked all our adjacent neighbors if they were ok with it and everyone said yes.

    The shed will not stand up to building code, it is not built to live in! It would have to be completely remodeled for tens of thousands of dollars if we wanted to do that. Has anyone else dealt with this? We are at a loss. 

    I am not sure who is telling you this since you didn't go through the permit process - an inspector making a spot house call? Weird, and that means yes one of your neighbors reported you. I would contact your councilmember's office for assistance, and include the code section that says under 120 sf is exempt.

    Hi, I'm a GC in Berkeley, build outdoor structures, treehouses, some sheds, decks, etc. I don't know if I can help you right off, I've never heard of the building department (in berkeley or anywhere) come up with such requirements, ie no windows. If I may ask, how did they recome aware of the situation? If you don't know, it sounds like it could have been a neighbor complaining. I build treehouses with windows, as long as they're less than 120sf and not over 12 ft high, I don't worry about it. Very interested in knowing more.

    I'd send them a copy of their own building code and notate that there is nothing in the code about a shed having windows and deck around it, it must be permitted.  Seems unfortunate that the CoB is going to lengths like this to harass people who have tool sheds.

    Wish I were an attorney to give you a more concrete strategy, but like you said, this is bogus.

  • Pre-fab in law

    (1 reply)

    Does anyone have experience with installation of pre-fab units? We are interested in installing a unit in our yard with a studio and bathroom. Hoping someone has recommendations for a company or any other insight which would also be appreciated.

    RE: Pre-fab in law ()

    Hi, we asked a similar (ish) question on BPN several years ago, and someone responded that they had used a backyard shed (by I don't recall the company name) and hired a contractor to "upgrade" it, and liked it - you might look for that older question and replies. Would have been asking about ADU's, backyard cottages, or granny flats. 

    We've now started down that road, but are hiring a contractor to do a design/build for us (so not a fancy shed). Just at the beginning of the process, so no real insight to give. There are a couple of pretty high priced companies that specialize in the burgeoning ADU scene; we found one who charges less; the proof will be in the pudding of course once the unit is built. 

    I recall we found a company or two that specialized in the "prebuilt"; the name Summerwood comes to mind. But it was hard to figure out where we might see their models, visit an already-built structure, and determine whether savings would actually accrue by going prebuilt. We are happy to be using a design more of our choosing. At the time, googling prebuilt backyard cottages found quite a few options; fewer that worked in California 

    Best of luck in determining which way to go. You are joining LOTS of families doing the same thing in Berkeley now.  

  • Hi, we're considering building a backyard cottage in Berkeley,  and are seeking information regarding if and how rent control might impact this decision. Does anyone know for sure?  We've heard all types of conflicting information, and can't get a response from the rent control board. Can anyone help?  Have you recently built and rented an ADU, and did anyone set limits on the rent you could charge?  Any recommendations for groups or organizations that can help new landlords?  Appreciate your thoughts, recommendations, and information. 

    When I looked into it in the last couple of years, ADUs in Berkeley are not rent controlled. There are a lot of requirements about who is allowed to build them and how they're built (off-street parking, set back from property lines, etc.), so definitely look into that. Also, the rent control board always seemed to respond pretty promptly to any questions we had. Have you tried calling them?

    New construction is exempt from rent control but no eviction control. You can't give the tenant 30 or 60 days notice to move without good cause, but you can raise the rent so high that they decide to move. Here is a list of "Partially Exempt" rentals: 

    http://www.ci.berkeley.ca.us/Rent_Stabilization_Board/Home/Guide_to_Rent...

    New construction must be COMPLETELY new, from the foundation to the roof. Do not convert a garage if you want to be able to raise the rent. In addition, you are free to charge whatever you want at the beginning of each tenancy. Rent control only applies to sitting tenants. 

    I suggest you join Berkeley Property Owners Association. You may also want to contact Michael St John for advice. 

    https://www.bpoa.org/

    I am working with a client on the same issue. It is my understanding that you will need to register the ADU with the rent board but it will not be under rent control regulation. You are not supposed to use it as an AirB&B or short-term rental but can charge any rent you want.

Archived Q&A and Reviews


Questions

Have you researched or built a backyard cottage?

Jan 2014

Hi, we're considering building a backyard cottage (ADU), in Berkeley. This would be both an income-generating prospect (hopefully), and possibly a home for either the grown children, or a caretaker depending on how health goes. Have you done this recently? Which design/build (or other) company did you use? Seems like the one we hear most about is 'new avenue', but then we've also heard they were a spin-off from an original company, who we can't seem to find. Any company recommendations? I'd assume you had 3 bids, but again we're not finding multiple companies who do this.

I understand this can be a loaded question, but approx how much did you end up spending? (We're in Berkeley). Any recommendations for 'where to start' the process?

Thanks for any recommendations, advice, warnings, etc. Hopeful backyard cottage rental unit owners


I researched and built a backyard cottaage about 6 years ago. Strongly suggest first going to the planning office to learn what regulations you'll need to pay attention to. And find someone proficient in Berkeley rental law to understand that too.

After an architect took me to the cleaners (her fee almost 40% of the total project fee) I ended up getting a tuff shed garage and tricking it out on the interior. All told, $50K ish. Depends of course on your budget and what you're looking for.

The City of Berkeley was the most painful part of the entire thing - it was an endurance event of pain, waiting, obfuscation, and delays. Insane. Utterly. Loved my cottage in the end but the whole thing took years off my life. Good luck! Do your homework


First off, don't advertise that you expect to have income from the Cottage. It is easier to get approval for an 'In-Law Unit' than for a rental, or 'Secondary Unit', and sometimes neighbors can make life difficult if they think you are renting an 'In-Law'.

I have designed some ADU's and gotten them through the permitting process - others have built them. The last one cost around $135k, in 2009. It was about 400 sq. ft. Came out really nice, used by the grandma when she's in town, who is brave enough and agile enough to utilize the loft. The person who built it has moved on to bigger things, but I team up with Springwood Builders when I can.

I know this forum is not for us to talk up our businesses, but I also have some 'advice' that can be helpful to anyone who is considering this. I think the best way to start off is to go to the Planning Dept. with a sketch of the property with the approx. locations of the main house and the proposed cottage. You might be told by the planner that you can situate the cottage far back on the lot, b/c you are already getting a use permit. Careful on this, b/c it can lead to a requirement of automatic sprinklers, an expensive proposition. I could go on, but ...

I hope this helps. . Andus B


We used a company called Summerwood - highly recommend them. Great products, incredible customer service, great 'help' department. We built in Alameda and yes, planning department was the worst part of the experience. We also worked with an architect at first - he proposed us spending over $100k for about 400sf (which was $50k over budget). We purchased the 220 sf unit for about $11,000, and finished (electricity, sheetrock, lighting, painting, furnished came in around $18,000). The great thing about summerwood is you design the until - pick where the widows and door go, etc. We built what is typically a pool house but will tuck into a corner. We lived in our studio as much as the house, perhaps more. Its a great investment. good luck


Backyard Cottage/Tiny House - have you built one?

May 2012

Hi, We're considering building a 'Backyard Cottage' or 'Tiny House' in our backyard in the Berkeley flats. We're unsure how to proceed, and want to ask some locals about the pros and cons. We're thinking 400 sf or so, to use as a rental and/or when visitors come.

I understand that Berkeley is replete with such structures, and there's the one well-known one that got a lot of press last year (the UC Berkeley professor). But, have others built them recently? If you have, who did you get to do the construction, and did you buy a plan or have one firm do the design/build? What was the total cost, and what do you rent the cottage for? Would you recommend doing it? Pluses and minuses?

Thanks for any information, advice, recommendations, cautions... Hope to add small unit


Dear Hope-to-add-small-unit, I designed an In-Law Unit recently for a client in the flats of Berkeley. It is 450 square feet and cost about $130k, not including pre-construction costs. Eric Manou built it. In-Law Units are easier to permit than rentable units, which require a use permit with a public hearing, separate utilities, etc. I hope you enjoy the process.


I recently designed a small cottage in Alamo. It was 776 square feet and construction estimates came in at around $220K. You'll want to look at the zoning requirements for your lot and confirm setback distances and height limitations. You'll also want to look at parking requirements to determine if an additional parking space will be necessary. Lastly, talk to the city about permit fees for your project. The fees required for a project like this are often greater than clients expect.


I have to say that, in order to expand space potential for our tiny Albany house, we ordered up a backyard cottage from the Shed Shop in Fremont: http://www.shedshop.com/ This was probably nine years ago, but the cost came in at under $80,000, including the concrete slab foundation we put in, and the shed is still going strong. This was a one-room thing, however, with electricity and phone line. Not a mother-in-law unit. But worth looking at for extra space. spatially challenged


We went down the architect path for a small backyard cottage and it was a nightmare that cost us $7,000 in fees with nothing at the end as our $60,000 budget became an unfinished unit estimated at $110,000. Then we found Summerwood - and spent $12,000 for a 'pool cabana' that fit perfectly in the corner of our yard. It's 220 sq feet, and when you add Sheetrock, electricity, roof, lighting it was just about $20,000. We then re-did our yard and it all looked/s amazing - and was way, way better than the 400 sq foot planned structure. We could have easily added a sink, but for a toilet would have need to trench across the yard - do-able but we decided a second bathroom in the house made more sense. Happy to tell you details of our summerwood experience - amazing! No waste (all the wood is precut) - we love the windows and doors. Our house has been on a number of garden tours and people always ask about the structure. Love our cottage


Prefab backyard bungalow/cabin/in-law?

Jan 2011

Hello, We are considering the most inexpensive way to add a small 'bungalow' / cabin / in-law apartment to our Berkeley backyard. Has anyone used one of the pre- fab 'kits' for building such? Which company did you use, and how was it? How is it holding up? Other ideas for rather inexpensively adding a live-in 'apartment' to our backyard? Any recommendations/ suggestions welcome. Thank you! Need a little room


We had an estimate from an excellent contractor who specializes in prefab in law cottages. I have seen several that this contractor made and they were beautiful little homes. His price included all cabinetry and kitchen appliances. His name is Steve Vallejos and here's his email: Steve Vallejos stevevallejos [at] hotmail.com www.valleyhomedevelopment.com/ I can tell you more specifically if you want to call me: 529-6328. Micky


Not sure if this would meet your needs, but definitely worth checking out -- Tuff Shed. We built one several years ago to use as a workshop. Although ours is not plumbed or heated, I think you could add those things to the basic structure. Since it's on a slab, radiant heat would be ideal. We also added skylights (which are an option) and the space gets lots of natural light from them. We don't live in ours, but we know someone who does and it seems to work for him. Once you get all your permits in place, construction is super fast. Happy with Tuff Shed