About tiny houses

A tiny house is a dwelling that may be built on wheels and is no larger than 400 square feet, including a kitchen, bathroom, and sleeping/living area, and must be built to the Washington State Building Code. The approval process for a tiny house depends on where it's built.

On this page, you can determine whether you need approval of construction plans and inspections from L&I or the local building department where the house is being built.

  • If you're building a tiny house somewhere OTHER than where it will be occupied and used, then see the Building a Tiny House tab.

Next, see the building a tiny house tab.

Contact us 

FAS1@Lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia, WA 98504-4430

Location
7273 Linderson Way SW
Tumwater, WA 98501

Building a tiny house

L&I is the building department for the construction of tiny houses that are built at offsite locations, such as a factory or even a back yard. L&I reviews plans and inspections for tiny houses built offsite from where they will be placed.

NOTE: The design of your tiny house must also meet local building department criteria. Contact your local building department for their requirements and permit information.

To get a tiny house approved:

First, Download and review the tiny house information packet. It includes the standards to which you need to design, plan, and build your tiny house.

We will need 3 copies of your plans. Plans must be stamped by a Washington professional engineer (PE) or architect.

Next, fill out these applications:

  • Tiny House Plan Approval & Insignia Request form (F623-039-000): This is your basic application and gets the insignia for the L&I inspector to place on your tiny house. The insignia is also important when talking with your local building department when you place the residence.

  • Notification to Local Enforcement Agency (F623-013-000): This is included with a copy of your plan that is sent to the local building department upon L&I approval.

Finally, include payment of $775.00 for plan review and insignia. We will notify you if we need more information or when your plans are approved.

Mail the completed packet to:

Department of Labor & Industries
Factory Assembled Structures
P.O. Box 44430
Olympia WA 98504-4430

You can also submit your plans at your local L&I office, and pay the fee by cash, check, money order, or credit/debit card.

Because of the large number of requests, it can take several months for L&I to review plans. We will notify you if we need more information or if your plans have been approved.

Next, see the do the work tab.

Contact us 

FAS1@lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia, WA 98504-4430

Location
7273 Linderson Way SW
Tumwater, WA 98501

Do the work

Once plans for your tiny house are approved, you can start work.

Some important notes about licensing requirements:

When you build a tiny house there are several registration, and licensing issues you need to be aware of and consider.

  • You may need to be a registered general contractor depending where you are going to work on a tiny house, and what duties you are performing. Contact L&I's contractors program to find out the requirements for your situation.
  • All plumbing must be installed by a Washington state licensed residential or commercial plumber.
  • All electrical work must be performed by a Washington State licensed electrical contractor and licensed electricians. You will need to get an L&I electrical permit to connect your house to power.

There are exceptions for homeowners doing electrical and plumbing work on their own house. Please contact L&I's plumbing program and electrical program to determine the licensing requirements for your situation.

Note: Local building permits will be required for everything from the tiny houses foundation, installation, and its location on a property. Remember to contact your local building official for more information.

Next, see the get inspected tab.

Contact us 

FAS1@lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia, WA 98504-4430

Location
7273 Linderson Way SW
Tumwater, WA 98501

Get inspected

You will need to have your tiny house inspected several times by L&I as you complete certain stages of construction. You must contact us using either an in-state or out-of-state inspection request form before covering any work on the house. Our inspector will contact you to confirm an appointment.

When you need an inspection depends on when you complete the stages of construction shown on the form. This can include:

  • Floor.
  • Plumbing.
  • Electrical.
  • Frame.
  • Mechanical.
  • Energy Code.
  • Final.

Be ready for the inspection. If you've requested an inspection and you're not ready, you will still be charged. If the inspector must return to the location, you will be charged additional fees.

Contact us 

FAS1@lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia, WA 98504-4430

Location
7273 Linderson Way SW
Tumwater, WA 98501