Other Mobile or Modular Structures

The following structures require permits:

• Modular buildings: Buildings which are constructed in factories and at other offsite locations and then shipped to Washington must be approved by L&I. This includes equipment shelters that can be entered by personnel.
  • To get a modular building permit, submit plans showing the design and construction of the buildings. Download an information packet for Modular Building Manufacturers (1.3 MB PDF).
  • Alterations require an L&I permit unless the building is being installed on a permanent foundation. In that case, permits from the city of jurisdiction and the L&I Electrical program are required.
• Temporary Worker Housing (TWH): TWH units fabricated in factories and being shipped to Washington State must be inspected by L&I as they are constructed.
  • To get a TWH permit, submit plans showing the design and construction of the buildings. Download an information packet for TWH Manufacturers (887 KB PDF).
• Recreational vehicles and park trailer: All RVs and Park Model RVs for sale or lease in Washington State must bear an L&I approval label.
  • To get a recreational vehicle or park model permit, submit plans showing the design and construction. Download an information packet for Recreational Vehicles (841 KB PDF) or download an information packet for Recreational Park Trailer Manufacturers (810 KB PDF).
• Commercial coaches: Commercial coach trailers must be inspected and approved by L&I.
  • To get a commercial coach permit, submit plans showing the design and construction of the unit. Download an information packet for Commercial Coach Trailer Manufacturers (1 MB PDF).
  • Alterations also require an L&I permit and inspection.
• See examples of labels for these structures.

Here's how to submit plans:

• Mail the plans to the L&I office nearest you.
• Walk in to the L&I office nearest you.