My claim of owning the first greenhouse-enclosed tiny home in the United States has received pushback that it is a) not tiny, and b) not the first. This spurred a conversation about the definition of both “tiny” and “home.” Should the use of the term “tiny home” be defined only in legal terms per the International Residential Code and/or local building codes? Or, is a social definition relevant? Whether using legal definitions or common use, the answer isn’t so simple. Respectful discussion in the comments is welcome.

The median new, single-family home built in the United States has been getting larger and larger for decades. In 2021 that was 2,273 sq ft. Although there were individuals writing about, and living in, tiny homes prior to 2007, the tiny home movement began in the United States in response to the mortgage crisis between 2007 and 2009. The 2007 collapse of the single-family housing market fueled a widespread need for more affordable housing. In this sense, a social movement (need for affordable housing) drove an architectural movement (tiny homes). Does that mean construction cost is relevant to the definition of “tiny home”?

In many areas of the country, the size increase is due to construction and land costs plus builders’ desired return on investment. In many areas of the country, the size increase is due to NIMBY-based building codes that defined the minimum square footage or minimum functions for a single-family home (e.g., “permanent provisions for living, sleeping, eating, cooking and sanitation”) and prohibits auxiliary dwelling units (“ADU”). Building and land costs have not declined but, changes to building codes have allowed permitting of a variety of ‘sub-sized’ dwellings as single-family dwellings and/or additional dwelling units on single-family lots.

On tiny home-oriented websites debate still rages between the ‘big tent’ participants and ‘small tent’ participants. The former use a more expansive definition of “tiny home” to include more housing options within the definition versus the latter who use more criteria than square feet (such as cost) to keep the application of “tiny home” to fewer options. There is no standard or agreed definition of “tiny home”, even within the tiny home movement, the tiny home channels, or websites. There are many who claim only a cabin qualifies. There are many who claim only a tiny home on wheels (“THOW”) qualifies. There are many who claim that because the tiny home movement began due to a need for affordable housing, to be considered a “tiny home” it has to be built for less than a certain cost.

My house is conventional stick-built on foundation with “permanent provisions” for water and power supply and sanitary-waste disposal. It is approximately 400 sq ft (37.2 sqm) of living space. It includes 1 bedroom, 1 bathroom with conventional plumbing and fixtures, a kitchen with conventional plumbing and full-sized appliances, a living room, and full-sized laundry washer and dryer. At 400 sq ft, 5 of my home could fit in the average-sized new, single-family home but it was not built for 1/5th the cost. It meets the definition of tiny and dwelling under applicable building code.

Definitions in Law

The legal meaning of “tiny home” requires a definition of ‘tiny’ and of ‘home’ but a quick survey of jurisdictions across the U.S. and Canada shows only moderate consistency in the definitions by the cities/townships/states that have defined these terms. This is not intended to be comprehensive or definitive. It is intended only to demonstrate some of the variability in the definition of what is a “tiny home” and that mine meets the definition within my state and local code.

Dwelling / Dwelling Unit

In general, building codes define a dwelling (i.e., a “home”) as requiring complete and independent facilities for permanent daily living. This definition means mere sleeping units that are supplied cooking and/or restroom facilities from a separate structure are not dwellings. It also distinguishes short-term rentals are not dwellings. Some cities/townships/states also define “dwelling” or “tiny home” as stationary or permanently attached to the land so as to distinguish from THOW that are governed by RV law.

Following is a brief survey of relevant code defining a ‘home’ or “dwelling”:

International Residential Code, Chapter 2. A dwelling unit provides for “complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation.” Also adopted by several states/townships/cities including but not limited to: Florida. Texas, and Alaska

Montana, USA. House Bill No. 494 Distinguishes a “tiny home” as a “residential structure on a permanent foundation . . .” from a “tiny home on wheels.” MCA 70-24-103 A single-family dwelling does not share “any other essential facility or service with another dwelling unit.”

Colorado, USA. House Bill No. 22-1242. A “tiny home” is permanently attached to a vehicle chassis but is designed for long-term residency.

New Jersey, USA. NJAC 5:28-1.2. Is one of the most lax definitions requiring only “living, sleeping, cooking, and eating” facilities but does not specify washroom facilities.

Oregon, USA. North Bend Building Code section 18.04.030 Definitions ““Tiny house” means a single-family dwelling not more than 600 square feet in floor area including loft floor area that is site built or prefabricated and permanently anchored to a foundation and provided with permanent utility connections. A tiny house is not designed to be movable or constructed on a wheeled chassis nor is it a manufactured home, recreational vehicle, shipping container, trailer, tiny house on wheels (THOW), or other similar object.”

Ontario, Canada. Tay Valley Township Zoning By-Laws. To qualify as a dwelling unit, “separate kitchen and sanitary facilities are provided for the exclusive use of such persons with an independent entrance from outside the building or from a common hallway or stairway inside the building.”

Maximum Square Footage

There is not a set maximum number of square feet or square meters that define a tiny home. That said, the International Residential Code: Appendix Q Tiny Houses provides exceptions to some residential code for homes that are less than 400 sq ft. excluding lofts. It does not state that only a home 400 sq ft or smaller may be called a “tiny home”; only that the house must be that size or smaller to be exempt from select code that is applicable to larger dwellings. Because many jurisdictions follow the IRC, 400 sq ft seems to be the most common definition of a tiny home.

Note that the IRC excludes loft space from the 400 sq ft floor space maximum but defines loft space as “used as a living or sleeping space.” thereby providing for actual living or habitable space to be significantly larger than 400 sq ft.

Following is a brief, but not comprehensive, survey of relevant code defining “tiny” and the maximum habitable square foot limit:

Definitions by Popular Websites, Bloggers & Real Estate Sources

Even tiny home-oriented websites and bloggers do not define tiny home consistently. Just a few examples are below:

Tiny House Authority. There is a common definition that is based on legal certification but don’t get hung up on a number; intent to live minimally is more relevant. “Typically, tiny homes do not exceed 400 sq ft and that’s due in part to certification requirements and the desire to live minimally. We like to think of tiny homes as intentional living and therefore the square footage shouldn’t be based on technicality but rather your intentionality.”

Tiny Home Builders. “While there is no official definition of a tiny house, it is generally thought of as a small house, typically sized under 600 square feet. “

Realtor.com. “While there isn’t a set standard, a tiny house rarely exceeds 500 square feet.”

Quicken Loans Mortgage section. “. . . they’re more specifically defined as any home that falls under a maximum of 500 square feet. “

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