Portland generally does not require a building permit for a detached accessory structure 200 square feet or smaller and 15 feet or lower.
Zoning, setbacks, lot coverage, utilities, structural attachment, retaining walls, and historic or environmental review can still require approval.
What this tells youComputed rule answer
How precise this isComputed rule answer
Official data checkedPortland residential fences, decks, and outdoor projects
Next stepCheck the official shed/accessory-structure rules with your project dimensions.
No building permitDetached structure 200 sq ft or smaller and 15 ft or lower
Building permitLarger or taller structure, or work outside the exemption
Still verifyZoning, setbacks, lot coverage, utilities, attachment, and overlays