Accessory Dwellings

A one-stop source about accessory dwelling units, multigenerational homes, laneway houses, ADUs, granny flats, in-law units…

What are the rules where I live?

Rules for creating ADUs vary from place to place.  Check the table below for links to your area.

Please remember this is a volunteer-driven site!  If you don’t see your city, or the link for your city is wrong, please let us know with a comment below — or even better, do some digging and leave the correct info in your comment.  With your help, we can build an up-to-date list for the entire continent.

State/Province City/County
Alabama Opelika (Lee County) – see this comment
Arizona Phoenix (called a ‘guesthouse’)
California Lake Elsinore – “second unit”
Los Angeles – defaults to state standards
San Diego (City)
– “Companion Unit”
San Diego (County)
San Francisco – Castro District
San Jose (Section 20.30.150)
Santa Cruz
Colorado Boulder
Connecticut  Norwalk
District of Columbia
Florida Jacksonville – not allowed
Orange County
Idaho  Boise
Illinois Chicago – newly constructed ADUs not allowed, but older coach houses may be available for sale as units in a condo-like arrangement
Indiana  Elkhart County — see this comment
Maryland Howard County
Montgomery County
St. Mary’s County
Massachusetts  see this report
Michigan Detroit – Not allowed except carriage houses built prior to 1940 (p. 461)
Traverse City
Minnesota  Minneapolis
Missouri  Columbia
New Hampshire
New Jersey
New Mexico
New York New York City – Not allowed
North Carolina  Asheville


North Dakota
Oregon Beaverton – section 40.05

Hillsboro – section 88a
Oregon City
Salem – Not allowed
Pennsylvania Philadelphia
Rhode Island
South Carolina
South Dakota
Tennessee  Nashville
Texas Austin
– only by special exceptionEl Paso
Port Aransas
San Antonio
Utah  Provo City — see this and this and this
Virginia  Fairfax (city)
Washington Olympia
West Virginia
Wisconsin Madison (p. 28-199)

More details about Oregon cities

If the table above isn’t enough info for you, here is an older table that focuses on Oregon cities, and has some more details about specific regulations:  Accessory Dwelling Unit Zoning Codes .ADU Zoning Matrix

If you’re willing to add to this dataset for your state, please contact us.

Even more details about Portland, Oregon

For more in depth information on Portland’s ADU regulations, review the following information.An introduction to the rules governing ADUs in Portland, OR is contained in this on-line guide. Among its more helpful links are:

Portland also allows accessory structures, some permitted and some not, that don’t qualify as separate dwelling units yet often have attributes similar to ADUs. For a table-format summary of codes related to these other structures, check out this Accessory Structure (Informal) Code Guide.

67 comments on “What are the rules where I live?

  1. Chris Neubecker
    May 9, 2014

    Thank you for sharing this information. This is wonderful research and will help planners in other communities trying to promote ADUs to advance this cause in our own jurisdictions.

    • linamenard
      May 9, 2014

      Dear Chris,

      We’re so glad you’ve found the information on helpful. As you noted, we hope it assists planners to promote ADUs throughout the country.

      Lina Menard
      A fellow planner and coordinator of the ADU Case Studies Project

      • Chaim Fialkoff
        July 6, 2015


        Does anyone know of ADU regulations governing multi-family, mid-rise or high-rise structures as opposed to low-density buildings.



  2. J. Schmidt
    May 9, 2014

    Anything known about Long Island/Suffolk County/Brookhaven Town?

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  5. Lora Shaner
    September 5, 2014

    How about Nevada – particularly Las Vegas?

  6. Sharri Chaidez
    September 9, 2014

    I live in Sacramento, California. I have been contemplating adding a 4/plex to my current property, but I’m not sure of the codes or regulations regarding this type of addition. My residence is also considered a historical property. Where would I begin to find information about adding an adu?

  7. Pingback: What to Know Before Building a Guest House | Your San Diego Real Estate Source!

  8. captainlucianchiroptera
    September 15, 2014

    I’m curious if there has been any word if Salem, OR will be changing it’s laws any time soon, or if I should start looking for places around Salem, while I maintain my current place of employment…

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  10. Dylan
    October 2, 2014

    Columbia, Missouri now allows Accessory Dwelling Units in all R-2 zoned residential lots, excluding two neighborhoods / overlay districts. While the majority of residential lots in the city are zoned R-1 and are not affected by the new ADU ordinance, it is possible for future ordinances to extend this to the R-1 residential lots as well.
    The relevant information can be found on the City of Columbia’s website:

  11. Ridge Turner
    November 19, 2014

    This is what I could fine for St Mary’s MD. Pulled from the ST. MARY’S COUNTY

    “May I build a second home/accessory apartment on
    my property?

    An alternative to a second home is an accessory dwelling unit. An accessory dwelling unit may be part of the principal dwelling or in a detached accessory structure (CZO Section 51.3.105.a.1). If part of the principal dwelling, it must be at least 300 square feet but may not exceed 30 % of the gross floor area. If in an accessory structure, the dwelling unit may contain no more than 2 bedrooms and may not exceed 50% of the gross floor area of the accessory structure (CZO Section 51.3.105.a.2).
    Accessory dwelling units are permitted in all zoning districts except in the CC, I and OBP districts (CZO Schedule 50.4.105).
    Accessory dwelling units are not subject to density limitations except in the RCA Critical Area overlay where they are considered a principal dwelling unit (reference to be provided). Thus, properties outside the RCA Critical Area are permitted “by right” to an accessory dwelling unit provided a building permit is obtained. There may be only one accessory dwelling unit per lot or parcel (CZO Section 51.3.105.a.3).
    Related Issues
    Contact the Health Department at 301-475-4321 for well and septic system requirements.

  12. Lynn Poindexter
    November 21, 2014

    Question: If an ADU existed before a property was annexed into a city, is it typical for that ADU to be considered ‘grandfathered against such city’s rules? Any insight greatly appreciated!!!

    • Martin John Brown
      November 29, 2014

      Grandfathering would be reasonable to me, but obviously you need to confirm with your particular local authorities to see how they interpret things. Good luck!

  13. Lee
    November 29, 2014

    Who do I contact for Sussex County in Delaware?

  14. D Jones
    November 29, 2014

    We are interested is this for the city of Elgin Illinois. We have a 115 year old home there. Anything you can find will be helpful.

  15. Martin John Brown
    November 29, 2014

    Hi Lee and D, your best bet will be to simply start calling around, for example the local planning or building permit office would be a good place to start. Let us know what you find out so we can post it here!

  16. Maxeem
    December 5, 2014

    Minneapolis, MN just passed ADU legislation to be allowed city-wide! :D

  17. Bryce
    December 6, 2014

    Hello, for the town of Norwalk, CT, here are the rules for an “Accessory Apartment:”

  18. Tom H.
    January 15, 2015

    Chicago has grandfathered in all existing ADUs (known locally and in the zoning code as “coach houses”), but does not allow new ADUs or expansions or major alterations to existing ADUs. Contrary to this site’s definition, in Chicago coach houses often are for-sale as stand alone condominiums as opposed to solely rentals on single-family properties.

  19. Jerry McIntire
    January 20, 2015

    Viroqua, WI doesn’t have any provision for ADUs in its zoning.

    • Martin John Brown
      January 21, 2015

      Hey Jerry, thanks for your comment. Can you clarify a bit about Viroqua? The long document you link to doesn’t seem to mention ADUs (I did a text search for “accessory dwelling”) but I’m not sure what this implies. ADUs aren’t mentioned and therefore… you can’t do them? or … you can do whatever you want? –Thanks!

      • Jerry McIntire
        March 3, 2015

        Martin, there is no provision for them so you can’t do them. If a lot is zoned for a duplex (many are) you can build a second residence. It must be at least 600 square feet.

  20. Burkley Allen
    January 22, 2015

    Nashville, TN passed an ordinance in 2014 allowing Detached Accessory Dwelling Units in residential areas zoned to allow duplexes.

    There was reluctance in areas that had downzoned to single family only to allow DADU’s as a blanket policy. Now some areas would like to come up with a “hybrid” zoning that would allow DADU’s but not full sized duplexes.
    Does any other city have a policy similar to that?

  21. carol
    February 24, 2015

    Regulations for Alameda County: Alameda and Castro Valley?

    • Julie
      July 30, 2015

      Did you find what you were looking for? Thinking of getting a tiny studio on my property and renting it out.

  22. Mona
    February 27, 2015

    We are up in Bellingham, WA. Our situation is a bit unique as we own a SFR, that we would like to convert to an ADU once we build a new house out in front of it. This is our place which we currently rent and she loves it: [link deleted for privacy’s sake — ed.]

    It was built with this idea in mind, to convert to an ADU, therefore was built to conform to ADU code. Within the city limits of Bellingham the ADU must be attached to the main residence. We had a designer help us with plans for the house and connection to the (hopefully) converted ADU. The code specifying the connection is very vague – really non-existent. It just says the structures need to be attached. The garage/ADU sits on the very back of the lot. Our design placement put the main house on the front of the lot as far forward as possible to allow a backyard between the ADU/main house. The connecting room would open onto the backyard, creating a courtyard feel. The City decided they did not like our connection design (too long), even though the code does not specify how it connects. They denied us. We withdrew our application as they said no way. Grrrr.

    The ADU Ordinance is now being revisited by the City Council and Planning Dept over the next few months, with the first meeting coming up next week. We will be active at those meetings, inform them of our situation and use your site for some of our references. It seems time the City entertain detached ADU’s as well. From everything I’m reading impact is negligible and outcome is positive. Our set up could not be more perfect for an ADU situation. I see why people give up trying to get approval, very frustrating!

    If you have any information or tips as we go through this process with the City, I’d appreciate it! We are hopeful things will turn in our favor so that we can resubmit converting this lovely place. We put everything on hold (have not started construction of the main house), hoping the tide will change and Bellingham will get more progressive with ADU development.

  23. Penelope
    March 3, 2015

    Does anyone happen to know the ADU laws for Sherwood, Oregon? I tried to find information online, but was unsuccessful. Thanks!

  24. Kirsten Sharer
    March 3, 2015

    Other Denver-Metro area, Colorado cities that allow ADUs-

    My husband and I (and my parents) are desperately waiting for Wheat Ridge to follow suite.

  25. Jim
    April 3, 2015

    Elkhart County, Indiana, as part of their Zoning Ordinance update, allows accessory dwelling units in the primary agricultural zoning district, subject to some specific use standards.

    This was done to better accommodate “dawdy houses,” which is a cultural practice among the Amish wherein older people or newer families live on the same property as a more solidly established relative.

  26. Roger Tetreou
    April 7, 2015

    Does anyone know the rules in Rhode Island? I have been reading a lot of information on the subject, but It always feels incomplete. And every time I call my town for information on any real estate subject they treat me like the scum of the earth and evade all questions–meanwhile treating me like scum some more. (most recently I asked, “what is the definition of a brick patio verses a brick walkway?” –I asked because a brick walkway does not increase property taxes. And I was passed around the city hall 7 times or more, and in the end received no answer.)

  27. Rain
    April 10, 2015

    Las Vegas? im planning on building a tinyhouse. and my mom has some space in her back yeard, or i might have to get some land. but it doesnt help that the tiny house will be in the city without a residential because its illegal to just have a tiny house on a lot, isnt it?

    • Martin John Brown
      April 10, 2015

      Hey Rain, thanks for chiming in. What kind of tiny house are you talking about building, one on a foundation or one on wheels? If it’s on a foundation, then it’s part of the property, and then it would be subject to whatever the rules for accessory dwelling units are in Las Vegas. But if it’s on wheels then it’s not part of the property; it’s more or less like an RV. Perhaps you should look up the rules for RV parking in Las Vegas. I know the “where to park” issue is a major one in the tiny house community, wish we could be more help.

  28. meghanduprey
    April 19, 2015

    has anyone found the rules for Asheville, NC (Buncombe County)?

  29. Rob
    May 3, 2015

    My son could use help with Sonoma County rules – can city rules allow something that the county questions?

    We are interested in the Isleton area/Delta area in California. Any information would be greatly appreciated!

  30. Nicole
    May 16, 2015

    i am looking into orange county….and have been searching everywhere! does anyone know where i might find more info on ADUs?

    May 29, 2015

    Please post siskiyou county california

  32. Nick
    June 13, 2015

    I found the following to be a comprehensive list of ADU building codes in a YES/NO format broken down by town for Massachusetts. The Data may be a little out of date but the document looks very useful.

  33. xogfog
    June 16, 2015

    Richmond, California “Second Dwelling Units” 15.04.810.020

  34. anabbeynormality
    July 6, 2015

    What are the rules/incentives about renting out my basement to a friend as an attached ADU vs just a “room rental” that happens to have a separate entrance?

    We are good friends, so there’s no issue with giving each other access to the rest of the house.

    As far as I can tell, the basement should be legally habitable (legal egress, adequate height, etc).

    It has a full bathroom (all work was permitted).

    There is no kitchen per se, but there is a working sink (other than the one in the bathroom) and it could be make functional with no new wiring or plumbing with some storage, a fridge, and portable appliances. We also told her that she would be welcome to use our kitchen when she wants a real oven or stove, and she was fine with that.

    I would love to make it a full ADU eventually, but in the short term, it may be cost prohibitive if I need to hire contractors to install an actual stove, or move our electrical panel to the “main house” and have a new meter installed. Is there any reason why I can’t rent it out as-is for now? I’m in Portland, OR.

    • Martin John Brown
      July 24, 2015

      If it’s a legally habitable room, as you say, you should be able to rent it out simply as a room in the house, just like you’d rent out a bedroom on another floor. The fact that this room is in the basement and has a separate entrance doesn’t mean it “has” to be an ADU.

      I don’t know if moving portable appliances to make a sort of informal kitchen would cross some sort of line, legally.

      But if you wanted to stay on the safe side of the line, maybe you could just have your room-mate share your kitchen, at least some of the time.

      Eli or Kol, any input?

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  36. Ashley
    July 29, 2015
  37. jessica
    August 26, 2015

    Prattville, AL

  38. Suzanne
    August 29, 2015

    Do you have a link for the rules in Alameda County, specifically Sunol, CA?

  39. Jon
    September 8, 2015

    Virginia, Fairfax City – Yes (with Restrictions_Age or disability requirement) with public hearing AND approval from city council required

    from website:

    Accessory dwelling units (more than one household)
    The City’s zoning regulations allow for one accessory dwelling unit in a single-family house. Accessory dwelling units are restricted to owner-occupied property where at least one occupant is 55 years of age or older and/or at least one occupant has a physical or mental impairment. Accessory dwelling units may include a kitchen, sleeping and bathroom facilities in addition to the facilities within the single-family house. Accessory dwelling units require a public hearing and approval by City Council.

  40. Roselin
    September 29, 2015

    Any specific regulations for Merced, CA.

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