What Are Tiny Houses?


Nearly all news stories addressing what are tiny houses say something like, “A common definition for a tiny house doesn’t exist…” Well we have good news; if you’ve been wondering just what a tiny house is, a definition has FINALLY been established! 

In 2017, Andrew Morrison and Martin Hammer wrote International Residential Code (IRC) Appendix Q: Tiny Houses, and after intense vetting and a three stage voting process, it was approved by the International Code Council (ICC). After months of effort, advocacy work, and overcoming a lot of obstacles, we are VERY pleased to reveal the official definition of a tiny house:

TINY HOUSE. A dwelling that is 400 square feet (37 sq m) or less in floor area excluding lofts.

Plain and simple! Why is it important to have a uniform tiny house definition?

• If you want to go the legal route for your tiny house build, at some point you’ll need to go into the building department. Using the right terminology will help officials see that you know what you’re talking about (which will make them more likely to give you a building permit and Certificate of Occupancy). 

• Being able to definitively answer the question what are tiny houses places us all on the same page when addressing the tiny house movement, what challenges we face collectively, and where we go from here. 

• Having a definition helps us know what a tiny house is NOT. A tiny house is not a Park Model (trailer type RV designed to provide temporary accommodations for recreation, camping or seasonal use). A tiny house is not a Manufactured Home (Manufactured Homes are built by a certified manufacturing plant as dwelling units of at least 320sqft with a permanent chassis to assure the initial and continued transportability of the home). As a point of clarification, Manufactured Homes are often misidentified as “Mobile Homes”. However, the term Mobile Home only refers to Manufactured Housing built prior to 1976. Anything built post 1976 in this classification is officially and legally referred to as Manufactured Housing. Finally, a tiny house is not an RV (vehicle designed as temporary living quarters for recreational, camping, travel or seasonal use). 

• A definition for Tiny House allows people in the community to speak with banks and other lending institutions and show them that the home they’re considering is actually a legally defined entity and one that comes with it’s own code language and guidelines. This makes the home much more official in the lenders’ eyes. 

• The official definition also allows those of us in Tiny Homes to work directly with insurance agencies to identify the home in legal terms. Once again, the inclusion of an official definition and an official code guideline (Appendix Q) legitimizes the home for insurance agents and their underwriters.

One of the most exciting aspects of Appendix Q: Tiny Houses, is that it creates a legal pathway for people to occupy their tiny as a full time residence by acquiring a Certificate of Occupancy (CoO). A CoO is not attainable through an RV certification, nor with Park Models. They are possible with a Manufactured Home but DIYers can’t legally build their own Manufactured Home. 

As far as the DIY builder goes, the only option for acquiring a CoO for a Tiny House (and thus a legal residence) is by following Appendix Q. 

This is really important because most of us living the tiny house lifestyle are looking for HOUSING options, not recreational options. In most  cases, without a CoO, you simply don’t have a legal residence. To be clear, there are locations around the U.S. and around the world that currently allow for people to live in RVs full time, or in homes without any code oversight. However, those areas are few and far between and they certainly don’t exist in most residential neighborhoods.

Some people in the tiny house community have suggested that a tiny house is simply a small home, outside of the realm of conventional housing. They suggest that the size of the home is relative to the inhabitants and not something that one can pin a number to. In fact, Andrew himself says something similar at our workshops and in his presentations when he discusses the “feeling” or “perception” of a tiny home. He talks about “Human Scale” as the focus of housing. For example, a family of 10 may not find living in 400 square feet to be an option. For them, an 800 sf home may be the way to go and it will, believe me, still fit the description “tiny.” It won’t, however, meet the definition of a Tiny House in legal terms. So yes, tiny may be relative from a feeling standpoint, but not from a quantifiable, legal perspective.

Find out more about Appendix Q, where things stand nationwide, and how you can help our mission to get it adopted into each state by clicking here. To find out how you can financially support the cause, and help us travel to different states to represent the Appendix with top building officials and commissions, please click here. Our GoFundMe campaign actually became one of their staff’s favorites and they donated an additional $1,000 to our cause!! <3

We have created an infographic (below) that sums up the details of this article and answers the question: what is a tiny house. We hope that it clearly lays out what a tiny house is and is not and who oversees each. 

Thank you for helping us spread the message that a standardized and legal definition for tiny houses finally exists! 



what are tiny houses


14 Responses to What Are Tiny Houses?

  1. Jerry McIntire November 3, 2017 at 1:08 pm #

    Nice meme, thanks for all your work on the definition and this handy graphic!

    • Gabriella November 3, 2017 at 1:09 pm #

      Thanks Jerry! When are you guys moving into your sailboat?

  2. Christina November 3, 2017 at 1:54 pm #

    Thank you for this article! I felt like the Tiny House I’ve been designing, though inspired by the movement, was too big to be considered as such. But with a footprint of less than 400 ft, I’m glad it qualifies here! 🙂 The plans are below:


  3. TJ Houston November 4, 2017 at 9:00 pm #

    Hello Gabriella,

    Congrats! You guys are moving along like gang busters. I’ve been out of touch for awhile, but last I knew you were working on codes for stationary (foundational?) tiny homes. Is this definition the culmination of that or does this include THOWs?


  4. Sonya Tafejian November 4, 2017 at 11:20 pm #

    Please change your definition to apply only to “Stationary Tiny Homes” – otherwise your definition is highly inaccurate.
    Tiny Homes on Wheels are also Tiny Homes. They are built to RV code. We can, and do, legally live in them. We can, and do, borrow to build them. We can, and do, insure them as dwellings.
    Thank you sincerely,
    Sonya Terri
    Tiny House Consulting- Zoning and Permitting
    Petaluma, Ca.

    • Andrew November 16, 2017 at 6:41 pm #

      Hi Sonya. I know you and I discussed this on Facebook the other day, but I want to make sure that it is clear here as well for our readers. What follows is basically what I said on Facebook, so don’t feel like you need to respond unless you want to. Like I said, it’s mostly for our readers so we don’t continue to see confusion in the TH community.

      As much as “Tiny Houses on Wheels that are built to the RV code” (like you describe) can do all the things you mention in your comment, that is VERY RARE for the majority of the United States. It is changes to local laws in California that have made Tiny House RVs acceptable as “houses”. Even then, the classification is not exactly accurate, because you are not allowed to build a Tiny House RV in a residential neighborhood as a primary residence, so it’s not really a house, per se. It’s an RV that the state is allowing some people to live in full time, in some very specific areas only.

      As far as the national conversation goes, a “Tiny House RV” is an RV. A “Moveable Tiny House” built to residential code is a house.

      I can’t stress enough the importance of getting this straight. As a member of the Oregon Code Committee, I heard top ranking members of the Building Codes Division (BCD), building inspectors, and fire marshals all say that a major problem in the tiny house industry is the fact that everyone refers to everything as a tiny house. There are definitions, and not using those definitions, is causing a lot of problems for people in the housing industries (from RVs to permanent housing).

      Here’s a specific example that we learned about last week during the Oregon Code Hearings. A woman who has an RVIA CERTIFIED Tiny House RV was told by both the DMV and BCD that they could not register her structure as an RV because the Code Committee was working on a tiny house specific building code. Here’s the challenge. What she has is an RV, not a house built to residential code standards which was what we were developing in the Code Committee. When I asked the BCD about this, the top ranking official I spoke with said the following (roughly quoted):

      “The biggest problem is the use and MISUSE of the term Tiny House. It’s essential that people make sure they are aware of the clear definition of each, and that they use them properly to describe exactly what it is that they are building because, an RV is not the same thing as a house.” When I told him about our infographic, he said (again paraphrasing): “That’s the sort of thing that needs to become industry standard in order to make sure we are all talking about the same things. So far, that’s not happening and it’s causing problems.”

      As you can see in this one case (of many similar), the misuse of the term “Tiny House” actually made it impossible for this woman to legally register her RVIA certified Tiny House RV. Keeping a loose interpretation of the term “Tiny House” does not ultimately serve the TH movement.

      We don’t get to change the definitions of things unless we do it officially. As of now, the definitions we used in the infographic are, in fact, the officially recognized definitions that are used by RVIA, HUD, the ICC, the DMV, and many other agencies. Again, it’s not up to us to determine how to define tiny houses until we make official changes WITHIN these agencies. Until then, we have to use the terms correctly so we can move the entire industry forward.

  5. TJ Houston November 6, 2017 at 3:49 pm #

    Also, I was curious about when Andrew was talking about going in to talk to (planning and zoning?) about making your tiny home legal as a residence, what did you have to do differently? Yours is a THOW, did you have to take the wheels off and put a foundation under it? I would very much like to know what was required as myself and I’m sure many other people are in the same position. Thanks.


  6. TJ Houston November 6, 2017 at 4:03 pm #

    Also, when did RVIA start regulating park models. Under what law or authority is this? Thanks.


  7. TJ Houston November 6, 2017 at 5:07 pm #

    Ok, I think I’ve got it now. RVIA regulates Park Model RV’s, NOT Park Model Tiny Homes which are built for

    permanent occupancy and are based on local building codes and can be owner built. It is a little confusing when

    it’s implied that only RVIA makes “Park Models”, without the identifier “RV’s”. So, I guess the definition of “Tiny

    Home” would change with the “type” of Tiny Home. So “Tiny Home” is actually a generic term like “RV” or

    “manufactured home” depending on the style, size and code it’s built to. Am I on the right track or is there

    something I’m not understanding correctly? Appreciate any help you can give me.


    • Gabriella November 9, 2017 at 3:16 pm #

      Hi Tj! Sorry for the delay. RVIA oversees RVs and Park Models. They also certify factory built tiny house RVs.

  8. TJ Houston November 9, 2017 at 5:57 pm #

    Hahaha!! Funny girl! Now you’re moderating me, LOL!!!

  9. Andrew November 16, 2017 at 7:13 pm #

    Hi TJ. Nice to hear from you again. You don’t quite have it right yet. I’ll try to clarify.

    RVIA is responsible for the inspection/certification of both standard RVs and Park Model RVs. I want to be clear on this next point: ALL Park Models are RVs; there is no such thing as a park model tiny house. People may tell you that they live in their “Park Model Tiny House,” but that is a definition they are making up and NOT a legally recognized definition.

    Anything that is built to RV standards (either NFPA 1192 or ANSI 119.5) is and will always be defined as an RV until changes are made within those organizations regarding definitions. Even if a state, county or city allows people to live full time in their RV, the classification of the structure itself does not change. It’s still an RV (or Park Model RV).

    There are two types of Tiny Houses by definition: Foundation Bound and Moveable. Both have to be built to meet or exceed the residential code. That code is either fully or partially based on the International Residential Code (IRC) in every state except Wisconsin (they use the International Building Code (IBC) not IRC). Both can receive a certificate of occupancy (CO) upon final inspection, something an RV cannot because it’s built to a lesser code (RV standards are not the same as residential standards).

    It’s pretty easy to build a foundation bound tiny house. A moveable tiny house is harder because of the fact that it has a chassis (trailer) and wheels. That said, as long as the house is built to the residential code, the chassis can be handled through Section R104.11 of the IRC “Alternative design, materials and methods of construction and equipment” on a case by case basis. The structure will have to be placed on a foundation that meets the intent of the code. There are ways to do this, so it’s not as “impossible” as many would have you believe.

    There is the possibility of using skids (beams) under a tiny house instead of a chassis, and that too can work as a “Tiny House” as long as the residential codes are all met.

    So, a structure built to the following codes (in regards to building what could be considered a house) will remain the following type of structure…

    RV code = RV (whether a park model or a traditional RV)
    Residential Code = House (whether a moveable or foundation bound tiny)

    In regards to our situation, the planning and zoning departments were totally cool with us. The building department, on the other hand, said we had to make changes to meet the Oregon Residential Specialty Code (ORSC) such as raising our ceiling heights, removing our stairs, installing emergency egress access in the lofts, etc. Instead, I co authored Appendix Q that changed the playing field for Tiny Houses. We have not resubmitted our plans since the approval of the appendix.

    As I mentioned in another comment, I sat on the Oregon Code Committee for Tiny Houses that completed our work last week (see our video updates on Facebook and on our code page: http://www.tinyhousebuild.com/code). We will have a tiny house code in Oregon starting January 1, 2018. Once that code is in place, it will be much easier to get approvals for hOMe, and many other tiny houses in the state. Unfortunately, the appendix we authored wasn’t a magic bullet and there is still work to be done on hOMe to meet the code appendix requirements.

  10. Tiffany Locke February 12, 2019 at 5:50 pm #

    Thanks for explaining how it’s important to talk to officials to learn about what you need to build the house, such as a certificate of occupancy and a building permit. When talking to someone, you’d probably want to ensure you find an official form your city so that they know the rules and regulations for your area. This would also be important when getting your certificate of occupancy or other permits so that you can get ones that will work in your area.

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