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Tiny Homes: Coming to a Neighborhood Near You?

Proud tiny home owners. Courtesy of Portland Alternative Dwellings.

Tiny homes are all the rage these days! You can’t turn on cable TV without coming across at least one or two shows about them, and there are numerous blog articles, websites, and even conventions about tiny homes. If they are so popular, then why don’t we see more tiny homes in our communities? 

The simple answer is that our zoning and building/construction regulations create significant barriers against them, especially if someone wants to live in a tiny home on a permanent basis. When I first started researching this issue, I thought that zoning restrictions would be the major limiting factor. As I dug deeper into the details, however, I discovered that construction/building codes are actually the primary deterrent to tiny homes being used as a permanent dwelling unit.

What is Considered a Tiny Home?

For the purpose of this post, I define “tiny home” as a small dwelling (500 square feet or less), with a kitchen and bathroom, mounted on wheels, and able to be pulled by a vehicle (see the photo above). A tiny home is not a very small house built on-site, or a traditional recreational vehicle (RV). But, as you will see, things start to get a little murkier as you dive into the details. 

Zoning for Tiny Homes

Relevant state law and local regulations deal primarily with camper trailers and recreational vehicles (RVs) that are used on a temporary basis, and not tiny homes on a chassis with wheels intended for permanent occupancy. Accordingly, most zoning codes treat such tiny homes as camper trailers or RVs, and usually allow them only for temporary, recreational use in campgrounds, RV parks, and occasionally in mobile home parks.

If a local government wanted to allow permanent occupancy of tiny homes in residential zones as another housing option, it would be relatively straightforward (although not necessarily easy) to address the following issues within a community’s zoning code:

  • Zones where they would be allowed;
  • Standards to be applied to tiny homes;
  • Minimum dwelling unit size/occupancy (if your code has such standards); and
  • Eligibility of tiny homes to be Accessory Dwelling Units (ADU).
A major issue is that most of the zoning provisions discussed above, however, pertain to a tiny home being treated as a permanent dwelling unit. And, therein, lies the dilemma.

Tiny Homes as Temporary Housing vs. Permanent Dwelling Units

In Washington State, a tiny home with wheels and a chassis is actually called a park model recreational vehicle (PMRV) and is approved only for temporary/recreational use in the state. A tiny home/PMRV with its wheels taken off and mounted on a foundation will still be viewed as a park model recreational vehicle and its use will still be considered as “temporary/recreational” (and not approved as a permanent dwelling unit). Exceptions in state law (RCW 35.21.684 and RCW 36.01.225), however, allow a PMRV to be used as a residence if it is located in a mobile home park, hooked up to utilities, and meets the other requirements of the applicable RCW.

While some tiny home owners intend to use them only for temporary living purposes, others want to use them as permanent, or long-term, residences. In most cases, however, a tiny home/PMRV cannot be converted into a dwelling unit. The International Residential Code (IRC) addresses dwelling units and requires that “permanent provisions for living, sleeping, eating, cooking and sanitation” be provided in a dwelling, along with other requirements such as heating, mechanical and energy efficiency provisions. For example, park model recreation vehicles are only required to meet minimal insulation requirements of R-5 for floor, R-5 for walls and R-7 for ceilings. In contrast, dwellings are held to a much more efficient requirement of R-30 for floors, R-21 for walls and R-49 for ceiling, providing greater energy sustainability. 

It is a long and involved process for a tiny home to be approved as a dwelling unit:

  1. A person would need to submit engineered plans to the Factory Assembled Structure Program of the Washington State Department of Labor and Industries (L&I) for the construction of a “modular building” (or to the local building department for a site-built tiny house).
  2. Those plans would be reviewed under the specific Washington State Administrative Code (WAC 296-150F) for conformance with the requirements of the IRC.
  3. Once approved, the builder would request inspections during the construction process until final approval had been obtained. 
  4. After final approval, the L&I inspector would attach the “Modular Gold Label Insignia” to the unit and a notice would be sent to the local building department, letting them know that the factory assembled modular unit is being transported to the intended end user site. 
  5. Permits from the local building department would be required, and they would need to approve the foundation and installation of the tiny home. 
  6. The local jurisdiction will typically instruct the owner of the modular unit to provide design engineering for foundation and anchoring attachments from a licensed Washington State engineer or require a L&I-approved general design for attaching the tiny home structure to a permanent foundation.    

All utilities (water, sewer, and electric) for a permanent tiny home would need to be connected in the same manner as a typical single family house; use of extension cords and garden hoses would not be allowed.

Need for More Clarity on Tiny Homes

Tiny homes are likely to remain popular for many years to come. However, there are many barriers related to their use as a primary residence, both from a construction standards and zoning perspective. The current requirements make it difficult for tiny homes to become dwelling units, and all but impossible for the “do-it-yourselfer” to build a tiny home and live in it permanently. If there is an interest in making this type of housing more feasible in Washington’s cities, counties and towns, then it may make sense for state and local government officials and tiny home advocates to meet and discuss methods for achieving that goal, without sacrificing safety, energy efficiency, or affordability.

Until that happens, a good place to start is doing some research on your own. If you're interested, here are a few resources I recommend for learning more about tiny homes:

If you have had experience with tiny homes in your community or have developed an approach to tiny homes, please contact me at

MRSC is a private nonprofit organization serving local governments in Washington State. Eligible government agencies in Washington State may use our free, one-on-one Ask MRSC service to get answers to legal, policy, or financial questions.

Photo of Steve Butler

About Steve Butler

Steve joined MRSC in February 2015. He has been involved in most aspects of community planning for over 30 years, both in the public and private sectors. He received a B.A. from St. Lawrence University (Canton, New York) and a M.S. in Urban and Regional Planning from the University of Wisconsin-Madison. Steve has served as president of statewide planning associations in both Washington and Maine, and was elected to the American Institute of Certified Planner’s College of Fellows in 2008.