Everything homeowners ask about building an ADU in Beaverton — answered with 2026 data.
Yes, ADUs are allowed in Any zoning district that allows a single-detached dwelling as the principal use, including residential (R/MR) and several commercial districts (per Ch. 20 land-use tables) in Beaverton, OR. The maximum size for a detached ADU is 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less. Attached ADUs can be up to 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less. Beaverton has an ADU-friendliness score of 7/10. Check our full Beaverton ADU rules page for complete zoning details.
ADU construction in Beaverton typically costs $150,000-$320,000. The cost per square foot averages $150-$300. Garage conversions are more affordable at $100,000-$180,000, while prefab ADUs cost $100,000-$240,000. Permit fees add Type 1 application fee plus valuation-based building permit fees (third-party guides estimate $2,500-$9,000) — Confirm with Beaverton Building Division to your budget. See our detailed Beaverton ADU cost guide.
Detached ADUs in Beaverton can be up to 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less. Attached ADUs are limited to 800 sq ft or 50% of the primary dwelling's gross floor area, whichever is less. Junior ADUs (JADUs) have a cap of N/A (Oregon does not use a JADU category). Maximum height is Per the underlying zone's accessory-structure/dwelling standards — Confirm with Beaverton Planning Division. You are allowed up to 1 ADU per detached dwelling unit (duplex/triplex/cottage-cluster options exist separately under HB 2001 middle-housing code); ADUs not permitted on middle-housing land-division child lots on a qualifying lot.
Rear setback: Per underlying zone accessory-structure standards — Confirm with Beaverton Planning Division. Side setback: Per underlying zone accessory-structure standards — Confirm with Beaverton Planning Division. Front setback: Per underlying zone — Confirm with Beaverton Planning Division. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
No additional off-street parking may be required (ORS 197.312, SB 1051/HB 2001). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required — Oregon law prohibits owner-occupancy conditions on ADUs. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Beaverton is typically Commonly 2-4 months total from application to permit issuance — Confirm with Beaverton Planning Division. Plan check: Included in building permit review — Confirm with Beaverton Building Division. Pre-approved plans availability: No city pre-approved plan library — Confirm with Beaverton Planning Division.
Average ADU rental income in Beaverton: 1-bedroom units rent for $1,400-$1,700/month, 2-bedroom units for $1,700-$2,000/month. Short-term rentals: No statewide ban; check Beaverton business-license and any STR requirements — Confirm with the City of Beaverton. Expected ROI: 6-8% annual return.
The minimum lot size for an ADU in Beaverton is No ADU-specific minimum; requires an existing detached dwelling as principal use. This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Beaverton, a garage conversion typically costs $100,000-$180,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.