Secondary suite

Jump to navigation Jump to search

Secondary suites, or accessory dwelling units, ADUs, or in-law apartments, are self-contained apartments, cottages, or small residential units, that are located on a property that has a separate main, single-family home, duplex, or other residential unit. In some cases, the ADU or in-law is attached to the principal dwelling or is an entirely separate unit, located above a garage or in the backyard on the same property.[1] In British English the term "annexe" is used instead. Reasons for wanting to add a secondary suite to a property may be to receive additional income, provide social and personal support to a family member, or obtain greater security.[2]


Relationship to main residence[edit]

A secondary suite is considered "secondary" or "accessory" to the primary residence on the parcel. It normally has its own entrance, kitchen, bathroom and living area. There are three types of accessory units: interior, interior with modification, and detached. Examples of these accessory units include:

  • A suite above a rear detached garage (a "garage apartment"),
  • A suite above the main floor of a single-detached dwelling,
  • A suite below the main floor of a single-detached dwelling (a "basement suite").
  • A suite attached to a single-detached dwelling at grade, or
  • A suite detached from the principal dwelling (a "garden suite" or "guesthouse").
  • A habadu, granny flat, or laneway house are other names for an habitable accessory dwelling unit.

Mother-in-law apartment[edit]

A mother-in-law apartment is a small apartment accessory to a primary residence. Alternative names include "granny flat", "granny annexe", "granny suite", "in-law suite", and "accessory apartment", the first being used primarily in Australia and New Zealand, where it is the most familiar of these terms, but also in parts of the United States; the second is the most common term in the United Kingdom and Ireland. Such apartments are frequently used to accommodate an elderly relative who is incapable of independent living, but does not want a nursing home environment or other similar facility.

The apartment may or may not have a communicating door to the main house, but virtually always has a separate entrance and is usually not part of the original design. Many are located above the garage of the main house or as a separate building in the rear lawn.

Legal considerations[edit]

In many North American municipalities, secondary suites are illegal because they do not conform to the zoning or land use district the property is in, they have been developed without the proper permits, or they do not meet the local building code. However, some localities only prohibit the renting out of secondary suites, and allow occupation by a relative or guest, leading to the use of the term "mother-in-law" house or apartment. Local jurisdictions may have rules regarding allowing certain relatives to live there and rules about what, if any, rent may be charged.

By country[edit]


Dual occupancy is sometimes used to refer to the development of two dwellings on one allotment of land. They may be either attached (semi-detached) or detached.[3] The term is common in Australia. A dual occupancy can be either torrens titles or strata titled.

A 'dual occupancy' in Victoria, Australia is a means to add value to property through a subdivision of one lot into two. It is that subdivision that makes dual occupancy an attractive proposition for new property investors and developers.

A 'granny flat' in Australia is actually also known as a secondary dwelling on a property, which is totally different from a dual occupancy. It does not require subdivision of the land and its construction requires approval from the council or relevant authority. The certifying process between council or a private certifier depends on a few conditions.[4]


Government programs[edit]


The Canada Mortgage and Housing Corporation provides a financial assistance program to help Canadians create affordable housing for low-income seniors and adults with a disability within a secondary suite. The program is called the Residential Rehabilitation Assistance Program (RRAP) -- Secondary/Garden Suite. The maximum fully forgivable loan depends on the location of the property:

  • Southern Areas of Canada: $24,000/unit
  • Northern areas of Canada: $28,000/unit
  • Far northern areas: $36,000/unit

A 25% supplement in assistance is available in remote areas.[5]

British Columbia[edit]

The Housing Policy Branch of British Columbia's Ministry of Community, Aboriginal and Women’s Services published a guide for local governments to implement secondary suite programs called 'Secondary Suites: A Guide For Local Governments'.[6] The current issue is dated September 2005. The intent of the guide is to "help local governments develop and implement secondary suite programs". It also highlights good secondary suite practices as well as providing practical information to "elected officials, planners, community groups, homeowners, developers, and others interested in secondary suites".


In Norway, particularly in the bigger cities, it is quite common to build separate adjoined smaller flats for renting out. The owner of the main flat will rent out the smaller adjoined flats.

United States[edit]

In the United States, secondary suites are technically referred to as accessory dwelling units or ADUs. An ADU is second complete dwelling unit which is legally built within or on the same lot as an existing single family residence. An ADU provides complete independent living facilities including a kitchen, bathroom and its own entryway. ADUs are typically not allowed to be sold separate from the primary home and the homeowners are usually required to reside in one of the two units.[7] State laws typically delegate planning and zoning powers to city and county governments which specify the appropriate type, distribution and intensity of land uses in the local jurisdiction.[8] As a result, the feasibility of building an accessory dwelling unit (ADU) (also known as a secondary suite, second unit, granny cottage, etc.[9]) can vary widely from place to place, depending on state law and each local jurisdiction's willingness to adopt regulations that facilitate ADUs.

Popular in the early 20th century, ADUs fell into disfavor after WWII, when a shift to suburban development occurred with emphasis on the nuclear family. However, with increases in the price of housing in many cities and suburbs, an increased awareness of the costs of low-density car-oriented development patterns and an increased need to care for the aging baby boom generation, ADUs have been promoted by some as a beneficial option.[10] However, some critics perceive ADUs to be a threat to the character of single-family residential neighborhoods.

In California, Government Code Sections 65852.150, 65852.2 & 65852.22 pertain to local regulation of ADUs.[11] SB 1069 and AB 2299 are California bills approved in 2016 and effective January 1, 2017, that limit local government authority to prohibit ADUs in certain cases (and also reduce cost and bureaucracy hurdles to construction).[12][13][14][15]

Santa Cruz, California has an ADU program.[16]

The County of Maui in Hawaii has an ADU program.[17]

Honolulu, Hawaii, has "Ohana Dwelling Units," which although similar to ADUs, limit occupancy to "family" and have other regulatory requirements.[18] Ohana Dwellings in Hawaii were created as an allowed use in the zoning code in 1981 as a way to encourage the private sector to create more housing units (without government subsidy), preserve green fields (open space) and ease housing affordability.[19][20][21] In 2015, Honolulu amended its zoning code to add a new use—ADUs[22]—as a sort of Ohana Dwelling, but with fewer restrictions. To prevent creating further complexities for existing Ohana Dwellings, some of which have been condominimized and owned separately from the main house, Ohana Dwellings remain an allowed use (with different requirements and benefits than ADUs) in the zoning code. Due to the poor turnout in the number of ADUs, Honolulu added incentives in 2016, waiving permit fees.[23] Fee waivers were extended in 2017.[24] ADUs are an important component to Honolulu's Affordable Housing Strategy.[25]

On December 9, 2016 the Seattle Times mentioned proposed legislation to allow more and larger mother-in-law apartments and backyard cottages in neighborhoods zoned for single-family houses in Seattle.[26][27]

See also[edit]


  1. ^ "Smart Growth / Smart Energy Toolkit - Accessory Dwelling Units (ADU)". Retrieved 2016-10-02.
  2. ^ "Smart Growth / Smart Energy Toolkit - Accessory Dwelling Units (ADU)". Retrieved 2016-10-02.
  3. ^ Planning & Land Management, Territory Planning Branch (2002). "Dual Occupancy Review" (PDF). Retrieved August 21, 2008.
  4. ^
  5. ^ Residential Rehabilitation Assistance Program (RRAP) -- Secondary/Garden Suite Archived 2006-09-09 at the Wayback Machine
  6. ^
  7. ^
  8. ^
  9. ^
  10. ^
  11. ^
  12. ^ SB 1069:
  13. ^ AB 2299:
  14. ^ Pender, Kathleen (2016-12-03). "New California housing laws make granny units easier to build". San Francisco Chronicle. Archived from the original on 2018-06-15. Retrieved 2018-07-12.
  15. ^ Wong, Queenie (2016-09-27). "California eases restrictions on 'granny units'". San Jose Mercury News. Archived from the original on 2016-10-19. Retrieved 2018-07-12.
  16. ^ "City of Santa Cruz Accessory Dwelling Unit Development Program". Retrieved 29 October 2015.
  17. ^ "Maui County Zoning Code, Section 19.35". Retrieved 15 August 2011.
  18. ^ City and County of Honolulu. "Revised Ordinances of Honolulu, (ROH) Section 21-8.20" (PDF). Land use Ordinance. Retrieved 15 August 2011.
  19. ^ "Ohana Housing Program Evaluation". Honolulu: Office of Information and Complaint. September 1984. Retrieved 15 August 2011.
  20. ^ Lau, Questor (May 2014). "Black boxes and gray spaces: how illegal accessory dwellings find regulatory loopholes". Retrieved 4 August 2016.
  21. ^ "Ohana Zoning a 5 year review" (PDF). State of Hawaii Legislative Reference Bureau. Retrieved 22 January 2015.
  22. ^ "Honolulu Ordinance 15-41 Relating to Accessory Dwelling Units" (PDF).
  23. ^ "ADU Status Update". 2/11/2017. Retrieved 2017-07-19. Check date values in: |date= (help)
  24. ^ "Honolulu mayor signs ADU incentive bill into law". KHON2 News. 2016-07-21. Retrieved 2017-07-19.
  25. ^ "Implementing [Honolulu's] Affordable Housing Strategy" (PDF). Honolulu Office of Housing. Retrieved 2017-07-19.
  26. ^
  27. ^

For New South Wales, the two approval paths are available. 1. If the Frontage of the land is 12m or more, a CDC (Private certifier) is possible. If less, then it must go through a DA(Council). 2. If above condition is met, another important requirement is the land size. If your land size is 450sqm or over, we can do a CDC approval. If it is less than 450sqm, we have to lodge the secondary dwelling application through the council.

External links[edit]