Tigard, OR · Zoning rules · Updated 2026
Tigard ADU Rules — Stricter Than Portland
Tigard caps ADUs at the lesser of 50% of primary dwelling or 800 SF. Many properties with 'Portland' mailing addresses (ZIP 97223, 97224) are actually inside Tigard's jurisdiction and follow this stricter rule.
The rule
Tigard caps ADUs at the lesser of 50% of primary dwelling or 800 SF.
Source: Tigard CDC 18.220.040
How big can your ADU be?
| Primary dwelling | Maximum ADU size | ADU as % of primary |
|---|---|---|
| 1,000 SF house | 500 SF | 50% |
| 1,500 SF house | 750 SF | 50% |
| 2,000 SF house | 800 SF | 40% |
| 2,500 SF house | 800 SF | 32% |
| 3,500 SF house | 800 SF | 23% |
Sizes reflect the code rule only. Site-specific setbacks, coverage limits, and overlay zones may reduce buildable envelope further.
Analyze your specific Tigard property
Drop an address to see the exact ADU size your lot allows, plus fourplex, cottage cluster, and middle-housing options. Includes construction cost estimates, exit values, ROI, and cited code sections for every constraint.
Analyze a Tigard addressBeyond the ADU rule
Setbacks + lot coverage
Each zoning district has its own front, side, and rear setbacks plus a lot-coverage cap. Our analyzer applies your zone’s actual limits automatically.
Parking requirements
Many jurisdictions have reduced ADU parking mandates under state law. We flag when your lot requires additional parking spaces.
Overlay zones
Historic districts, floodplains, and design-review overlays can override base zoning. We check the current overlay map for your specific address.
SDCs + permit fees
System Development Charges vary by jurisdiction and ADU size. Fees included in our cost estimates.