What
is a prefabricated structure?
A “prefabricated structure” as defined in ORS 455.010 means a building or subassembly that has been in whole or substantial part manufactured or assembled using closed construction at an off-site location to be wholly or partially assembled on-site.
“Closed Construction” as defined in OAR 918-674-0005 means a factory-assembled structure or component that encloses factory-installed structural, mechanical, electrical, plumbing or energy conservation equipment or material inside a floor, wall, or roof cavity which is not entirely open for visual inspection of the equipment or material at the site.
What is
not a prefabricated structure?
A prefabricated structure does not mean or include:
- “Manufactured Dwellings” (a dwelling built to federal HUD standards) defined in ORS 446.003.
- “Small Homes” (a dwelling that this 400 square feet or less) built to a residential code as defined in ORS 455.616.
Specifically ORS 455.616 Section 2, Chapter 401, Oregon Laws 2019.
(Note: This limitation is anticipated to end January 2026. Contact Program staff for additional information.) - “Transitional housing accommodations” established in ORS 197.746.
- “Recreational Vehicles” or “Park Model Recreational Vehicles” defined in ORS 174.101.
- “Tiny Homes” or “Tiny Homes on Wheels” used as temporary dwellings are under the purview of a local municipality (city council or county commission).
- “Backyard sheds” that are otherwise exempt from compliance with the Oregon Residential Specialty Code (ORSC).
Certain equipment shelters not regulated by the Program:
The Program does not perform plan review, inspection, or issue insignia of compliance for certain equipment shelters that are exempt according to Section 101.2 of the Oregon Structural Specialty Code (OSSC). Equipment shelters are primarily S-2 occupancies (as defined in Chapter 3 of the OSSC). They include, but are not limited to, structures for the protection of stationary equipment that are only occupied during maintenance or servicing of equipment, such as structures housing electronic switching stations, or communication equipment. Local building departments may require these equipment shelter comply with the OSSC.
Section 101.2 of the OSSC specifies that equipment shelters meeting the following criteria are exempt from the OSSC (all three must apply):
- Not intended for human occupancy
- Building area of 250 square feet or less
- Designated Risk Category I or II
This exemption does not mean the equipment shelter is exempt from other Oregon adopted specialty codes or laws. The local building department where the equipment shelter is to be installed will require permits for other systems installed in the equipment shelter (like electrical installations).
Manufacturers that want plan review and inspection services for these exempt equipment shelters have the option to either design the structure to be an occupied structure, or design the structure to Risk Category III or IV, or increase the square footage of the structure above the minimum size.
Important note: The information provided here is subject to change as laws, rules, codes, or other requirements change.