Do I need a permit for an accessory dwelling unit (ADU) in
Sherwood, Oregon?

Sherwood ADU permits — the key details

Oregon Revised Statute 197.314, which took effect January 1, 2020, prohibits Sherwood from denying ADU permits based on zoning, lot size, setback, or owner-occupancy. The city must approve ADUs that meet state minimums: a footprint of up to 800 square feet (or 75% of primary dwelling, whichever is greater) on any single-family lot, with side setbacks of 4 feet for a detached unit and 5 feet from the front property line. Sherwood's local code (Chapter 17.138.030) added a requirement that the ADU must have separate utility connections or a functioning sub-meter (not just a sub-breaker for electrical), which is more stringent than Oregon's state baseline. The city interprets this strictly: if you're converting a garage or adding an in-law suite, you cannot simply tap the primary dwelling's water line; the city's planning staff will flag it in pre-application. The rationale is that the city needs to track water consumption for sewer capacity planning in the Willamette Valley's volcanic-alluvial soils, which have variable percolation rates. A detached ADU typically requires a new water service stub, a separate meter (cost: $1,500–$2,500), a separate electrical service or sub-panel with its own meter (cost: $800–$1,500), and a separate sewer connection if the primary dwelling is on septic (cost: $3,000–$8,000 for a new tank and drain field depending on soil testing). Most Sherwood lots are served by city water and sewer, so the two-meter requirement is the binding constraint, not septic.

The city's ADU permit process is a combined building + planning review filed through the Sherwood Building Department (online portal at https://sherwood.civicweb.net or in-person at City Hall, 22560 SW Pine Street). The building division checks structural IRC compliance (R401–R403 for foundation, R310 for egress windows, R405 for energy, R406 for moisture), and the planning division confirms zoning envelope, setbacks, and that utility separation is shown on the plans. Pre-application consultation is free and highly recommended — a 30-minute call with the planning staff can clarify whether your lot layout, setbacks, and utility routing will pass the first plan-review round. Without pre-app, first submittals are rejected roughly 60% of the time (most common rejections: missing utility separation detail, egress window size non-compliance on junior ADUs, or front setback encroachment). After submission, Sherwood's plan-review clock runs 30 days for a complete set; the city typically returns a first round of marked-up plans with 5–10 conditional items, and you resubmit. A second review round takes 10–14 days. Total timeline from submission to building permit issuance: 6–10 weeks if you're organized; 12–16 weeks if you need two resubmittals.

Fees in Sherwood for an ADU permit bundle are calculated on a tiered basis: base building permit ($150–$200, flat), plus impact fee ($0.35–$0.45 per square foot of ADU floor area, roughly $400–$800 for a 1,200 sq ft unit), plus plan-review fee (2% of the estimated construction cost, typically $300–$800), and a planning conditional-use permit review fee ($250–$350). A detached 900 sq ft ADU cottage typically runs $1,300–$2,200 in city fees alone; a garage conversion (smaller footprint, less plan review) runs $800–$1,500. Design review is not required for ADUs in Sherwood (state law exempts them from local design overlays unless the city can prove design review applies equally to primary dwellings, which Sherwood cannot enforce). Third-party plan review, if the city contracts it out for complex projects, adds $500–$1,200, but most ADU plans are reviewed in-house.

State law also waives parking requirements if the ADU is within a half-mile of a fixed-route bus transit stop. Sherwood Transit operates one route through downtown (Route 1, Wilsonville Road), and most lots within a quarter-mile of that corridor qualify. If you're outside the half-mile buffer and cannot waive parking, you must show one off-street parking space (9 ft by 18 ft), which consumes lot area or requires a variance (additional $500–$1,000 and 4–6 weeks). The city's online zoning map marks the half-mile transit buffer; confirm your lot's location before finalizing site plans. If you are inside the buffer, request a waiver letter from the planning department; attach it to your permit application. This single waiver saves most Sherwood ADU projects $2,000–$4,000 in hardscape and retains lot flexibility.

Owner-builders can pull ADU permits in Sherwood if the ADU will be owner-occupied (ORS 701.005 and Sherwood ordinance 17.138.060). You cannot hold a contractor's license, and you cannot rent the unit; if you later convert to a rental, you must file a rental registration with the city (which triggers a final inspection to confirm all building-code items passed). If you hire a licensed contractor to build and you remain the owner-occupant, the contractor must sign the plans as responsible designer/builder, and you'll need an owner-builder disclosure form at final. Selling the property does not void the permit, but the buyer should assume the ADU as a recorded dwelling unit (updates deed and title); the city does not issue a Certificate of Occupancy for an ADU separately, only a sign-off on the building permit card at final inspection.

Three Sherwood accessory dwelling unit (adu) scenarios

Sherwood's strict utility separation rule and what it costs

Sherwood's Chapter 17.138.030 mandates separate utility metering for all ADUs, detached or attached, owner-occupied or rental. Oregon's state baseline (ORS 197.314) does not explicitly require separate utilities; it only mandates approval of ADU applications that meet square footage and setback minimums. Sherwood added the separate-metering requirement in 2021 to manage water and sewer impacts on the city's aging Willamette Valley infrastructure (volcanic-alluvial soils with variable percolation make capacity modeling difficult). This rule is legally defensible because Sherwood can prove it applies equally to all ADU types, so it's not discriminatory. In practice, it costs $2,500–$4,500 per ADU: a new water service lateral and meter ($1,500–$2,500), a dedicated electrical sub-panel or separate service ($800–$1,500), and a new sewer connection if the lot is on septic (rare in Sherwood city proper, but cost: $3,000–$8,000). For renters and second owners, these meters provide accountability — the city can read ADU utility consumption independently and audit compliance with occupancy limits (no unauthorized roommates inflating water use).

If your lot already has a sub-meter or split service from a previous renovation, the city may accept it if the plans show it clearly and a licensed electrician certifies the sub-panel amperage is adequate for the ADU's expected load. Do not attempt to run the ADU on a single circuit from the primary panel; this violates NEC 690.12 (service disconnects) and will be rejected at rough-in inspection. The city's electrical inspector is rigorous on ADU electrical separations because code-compliant sub-service is the baseline for future rental registrations and liability insurance.

If you are converting an attached structure (garage, studio) and cannot physically run a separate water line without major excavation, request a pre-application meeting and ask whether a sub-meter (two meters on one lateral) is acceptable as an alternative to a full separate service. The planning director has discretion to waive strict separation if the applicant can prove the constraint is structural (e.g., slab-on-grade with no mechanical room). This is not common in Sherwood, and you will need engineer certification. Most applicants accept the cost and route new lines.

State law overrides Sherwood zoning: what you can build that the city used to forbid

Before ORS 197.314 (effective January 1, 2020), Sherwood's code prohibited detached secondary dwellings on single-family lots and required lot sizes of 10,000 sq ft or larger for any accessory unit. Owner-occupancy of the primary dwelling was mandatory, and setbacks were 10 feet on all sides. State law erased all of that overnight. Today, Sherwood cannot enforce any of those restrictions. A detached ADU can sit on a 0.25-acre R-1 lot, non-owner-occupied, with only 4-foot side setbacks — all because ORS 197.312 and 197.314 preempt local code. The city's 2021 amendments to Chapter 17.138 aligned local code with state minimums, but many property owners and even some city staff still believe the old rules apply. They don't.

The practical impact: a neighborhood property that would have been ineligible for any secondary unit in 2019 is now eligible for an 800 sq ft detached cottage. A corner lot that was 'too small' (by 2019 standards) is now approvable. A homeowner who rents out the primary dwelling and plans to move is now allowed to build an ADU even if they don't occupy the primary house. If you encounter city staff resistance, cite ORS 197.314(2)(a)–(e) directly in your application cover letter: 'The proposed ADU complies with state law minimum lot coverage, side setbacks, and occupancy requirements. Local code variance or design review is not applicable per ORS 197.314(2)(a), which prohibits the city from imposing standards other than those specified in state law.'

One exception: the city can still require the ADU to comply with fire and life-safety codes (IRC R310 egress, R405 energy, R406 moisture), utility separation (Sherwood's local add-on), and parking if outside the transit half-mile. These are not subjective design restrictions; they are building-code minimums. But the days of Sherwood denying an ADU on a small lot or because the owner didn't live in the primary house are over.

Common questions