The Tiny house Blog

Washington Tiny Home Rules and Regulations

Updated on:
June 9, 2023
Tiny House Interior with an Island in the Kitchen and stairs to loft with a custom rail

Tiny homes with a foundation are popular in Washington State due to the regulations for ADUs in many communities. The codes and regulations may vary in towns, cities, or counties. For example, Woodland allows ADUs ranging between 300 and 800 square feet in size, and tiny houses in King County must have a foundation.

Despite the increasing popularity of tiny house communities, micro dwellers still face legal restrictions. Zoning laws and building codes offer certain limitations that you must know before building or buying a tiny house.

This post will provide deep insights into the tiny home rules and regulations in Washington State.

Read on and learn everything you need for a pleasant micro-living experience. 

Are tiny homes legal in Washington?

The state of Washington allows tiny homes, but regulations may differ depending on where you live. However, parking your tiny house on wheels (THOW) anywhere in the state is illegal.

You’ll find that different places have different rules for tiny houses. Here are the criteria for designating your tiny house accessory dwelling unit (ADU) in Washington:

  • Tiny houses built in King County must have a permanent foundation.
  • Woodland requires that the size range for ADUs must be between 300 to 800 square feet.
  • In Seattle, tiny homes are classified as ADUs, and they don’t allow THOWs.

What Washington counties allow tiny houses?

Washington is one of the tiny-house-friendly states in the US, and local laws are generally lenient for micro dwellers. However, the regulations may vary in towns, cities, or counties. Woodland allows ADUs of sizes ranging between 300 and 800 square feet and tiny houses in King County must have a foundation.

Generally, you'll find it easier to live in a micro home with a foundation in Washington than the one you need to park in a place. Regulations are not lenient for people who wish to park a micro house on wheels.

Can you permanently live in a tiny house in Washington?

You can permanently live in a tiny house in Washington. But make sure you consult your local building department before building one. Your micro house must comply with Washington State Building Code to get approved.

For tiny homes on wheels, you must have durability in mind when building if you plan to live in them permanently. However, the rule in Washington does not allow you to stay in a licensed RV for more than 180 days parked in the same spot.

Cute farmhouse style white and black tiny house on wheels with metal roof
View the Pacific Harmony Tiny House

How tiny can a house be in Washington?

A tiny house can be as small as 400 square feet or less in Washington. You may build it on wheels, including a sleeping/living area, a kitchen, and a bathroom. All tiny homes in Washington must comply with the Washington State Building Code.

There's an approval process for tiny dwellings depending on where you're building them. Here's how to get approved:

  • Familiarize yourself with the standards your tiny house should meet. The tiny house information packet has everything you need, including how to plan, design, and build.
  • Get three copies of your plan and have an architect or Washington professional engineer (PE) sign them.
  • Once done, you’ll need to fill out the following applications:
  • Tiny House Plan Approval & Insignia Request form (F623-039-000). This application gets you the L&I inspector insignia to place on your tiny home. It is the basic application, and the insignia comes in handy when dealing with your local building department.
  • Notification to Local Enforcement Agency (F623-013-000). Upon L&I approval, you’ll need to provide a copy of your plan and send it to the local building department alongside this application.

Lastly, you’ll need to pay $775.00 for plan review and insignia.

Mail the completed packet to:

Department of Labor & Industries

Factory Assembled Structures

P.O. Box 44430

Olympia WA 98504-4430

Alternatively, you can visit your L&I office and submit your plans. Fees are payable by cash, money order, check, or credit/debit card.

You should know that the L&I receives a large number of requests, and plan reviews might take several months. Rest assured that they will inform you once the plans have been approved or if they require more information.

Rules and regulations for tiny houses in Washington

Rules and regulations for micro dwellings vary in different parts of Washington State. Tiny homes with a foundation are popular thanks to the regulations for ADUs in many communities. Regulations are not lenient for people who wish to park a micro house on wheels.

In King County, tiny house owners must build their houses on permanent foundations. Parking tiny houses on wheels is against the rules and regulations.

Seattle also does not permit micro houses on wheels. All tiny homes must comply with the requirements for an ADU and must be registered for that purpose.

In Woodland, all structures classified as ADUs must have a living area ranging from 300 to 800 square feet.

Rules for permanent structures

Permanent tiny homes must be built to the Washington State Building Code. It must not be larger than 400 square feet.

Rules for temporary tiny houses

In Washington State, a tiny house with wheels is known as a park model recreational vehicle and is approved only for temporary use. You can't stay in such homes for more than 180 days parked in the same spot.

Where can I build a tiny house in Washington?

Local zoning and development regulations present challenges for micro dwellings on wheels. You can only park them in a mobile home/RV park or any other limited planning exception, depending on where you live. For other tiny houses, you can build them in a tiny house community, residential land, or agricultural property.

Zoning and development regulations that could apply include minimum size and parking requirements. Also, there’s a limit on the number of accessory dwellings on residential lots and occupancy limits which limit the potential for community living.

Do I have to pay property taxes for my tiny house?

You don’t have to pay property taxes for your tiny house, as this only applies to conventional homes. However, if the tiny house has wheels, it is classified as an RV in most states, which means that the personal property taxes levied on mobile homes might apply.

It’s important to know that regulations for motor vehicles vary for different states. You may need to pay the property tax imposed on motor vehicles depending on the state in which you live.

Where can I park a tiny home in Washington?

You have four options for where to park a tiny home in Washington: a tiny house community, an RV campground, a residential land, or an agricultural property. Micro dwellings on wheels are classified as RVs and you can only park them on an RV campground.

A tiny house community

Tiny homes are popular in Washington today thanks to the efforts of those pioneers of the micro-house movement. They have continued to push for the legalization of tiny houses. These communities include landowners from different backgrounds who lease spaces to microhouse dwellers.

Most of these communities focus on sustainability and may have a garden. Many look like a typical campground, while others offer more privacy and seclusion.

RV campground

You can park your tiny home at an RV campground if it has an RV or RVIA certification. It’s important to note that not all RV parks are tiny house friendly and not all tiny house communities are RV friendly.

Apart from the RV or RVIA certification, an RV campground can also be an option if your micro house meets the size requirements. Most national parks prohibit rigs longer than 42 feet from parking overnight.

On residential land or agricultural property

A residential area might be your best bet for where to park your tiny home. But you must tread lightly as every municipality is different. Ensure to do your due diligence before parking your micro house.

It could be your friend’s backyard or a rented spot from someone looking for additional income. This type of space may not seem like a permanent situation, but a residential space can be ideal for a prolonged period if local officials make an issue.

If you find yourself in a state that frowns at micro dwellings, parking in agriculturally zoned areas might be your best option. Many farmers have RVs or small campsites or cabins for their seasonal help. These full-time parkers usually get away with what they do as nobody tries to disrupt them.

Regulations and codes differ from state to state. So, you must research and do your due diligence to know if you can park a tiny house in your backyard. It also depends on the type of micro-house you want to build.

You will face some resistance if the tiny house is on your property. However, when building it in your backyard, ensure to double-check with neighbors and confirm that they are fine with it.

Are there tiny home communities in Washington?

There are many places where tiny house dwellers live side by side in Washington. As a result, there are also many flourishing tiny home communities and new ones are springing up.  

Finding a stable location for your micro house is an important consideration. While it may have wheels, it is not the easiest thing to move around. So, always consider the local state laws when looking for an ideal tiny house community.


Micro living has many benefits as tiny homes are easy to manage and less expensive to maintain. However, this lifestyle can be restrictive due to local zoning laws. Micro dwellers face legal restrictions and some regions are not tiny house friendly.

In Washington State, the regulations require tiny homes to be no larger than 400 square feet. Permanent tiny homes must be built to the Washington State Building Code. Tiny houses with wheels are known as park model recreational vehicles and are approved only for temporary use.

Washington is one of the most tiny house friendly states in the United States. It is home to many great tiny home communities and might be the perfect place to get a new micro house.

Find your dream tiny home today! 

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