Do I need a permit for pergola or trellis in Sun Prairie?

It depends. Whether pergola or trellis needs a permit in Sun Prairie comes down to the details of your project.

A solid, waterproof or louvered roof turns an open pergola into a roofed structure, which departments generally review like a patio cover, with attention to roof framing and wind loads. An open lattice or rafter pergola is the version most often treated as minor, so if you are comparing designs, ask your department how it treats each one before you buy a kit. Detached accessory structures are outside the UDC under SPS 320.05(4), so a freestanding pergola is regulated only by local zoning and building ordinances. Porches, decks, carports and similar structures attached to a home built on or after June 1, 1980 are within the UDC (SPS 320.02(1)(g)), so an attached pergola, especially one with a louvered or solid roof, may be reviewed as an addition. Local setback and zoning rules apply either way; the UDC does not override them (SPS 320.02(2)(b)). As of Sept. 1, 2026, SPS 316.012 requires an electrical permit from the designated inspection agency before installing a new or added electrical service, feeder or branch circuit serving a structure not already covered by an SPS 316 or SPS 320 permit, unless exempted by rule or statute.