Everything homeowners ask about building an ADU in Salem — answered with 2026 data.
Yes, ADUs are allowed in Permitted with a detached single-family dwelling, subject to the SRC 700.007 use standards and approved administratively with no hearing, in RA, RS, RD, RM1, RM2, RM3, CO, CR, CG, CB, IC, IP, IG, NH, MU-I, MU-II, MU-III, MU-R and ESMU (City ADU page; RD from the Ord. 13-21 zone table). Not allowed as accessory to middle housing - duplex, triplex, quadplex or cottage cluster (SRC 700.007; City Middle Housing page) in Salem, OR. The maximum size for a detached ADU is 900 sq ft or 75% of the main building's gross floor area, whichever is less (SRC 700.007; City ADU and Middle Housing pages, read Sept 2026). The City's free ready-build plan is under 600 sq ft. Attached ADUs can be up to 900 sq ft or 75% of the main building's gross floor area, whichever is less; an attached ADU may not have a direct interior connection to the main house and must have its own kitchen and bathroom. Salem has an ADU-friendliness score of 8/10. Check our full Salem ADU rules page for complete zoning details.
ADU construction in Salem typically costs $170,000-$330,000. The cost per square foot averages $175-$275. Garage conversions are more affordable at $90,000-$160,000, while prefab ADUs cost $120,000-$230,000. Permit fees add Valuation-based (FY2027 Fee Schedule Section 3): $645 for the first $100,000 plus $3.95 per $1,000, plan review 65% of that, a 12% state surcharge, plus trade permits - roughly $1,600-$2,100 for a 600-900 sq ft ADU valued at $175.92/sq ft. SDCs: $0. to your budget. See our detailed Salem ADU cost guide.
Detached ADUs in Salem can be up to 900 sq ft or 75% of the main building's gross floor area, whichever is less. Attached ADUs are limited to 900 sq ft or 75% of the main building's gross floor area, whichever is less; an attached ADU may not have a direct interior connection to the main house and must have its own kitchen and bathroom. Junior ADUs (JADUs) have a cap of N/A - Oregon and Salem have no junior ADU category; a room rental inside the house is 'taking of boarders', not an ADU. Maximum height is 25 ft for a detached ADU (SRC 700.007; City ADU page). Attached ADUs fall under the main house's zone height limit - confirm with Planning (503-588-6213). You are allowed up to 1 ADU per lot, attached or detached, with a detached single-family house only on a qualifying lot.
Rear setback: Not published on the City's ADU page; SRC 700.007 and the zone's accessory-building standards govern (Municode text could not be read in Sept 2026 - bot wall). Confirm with the Planners Desk, 503-588-6213, before drawing the site plan. Side setback: Not published on the City's ADU page; SRC 700.007 and the zone's accessory-building standards govern. Confirm with the Planners Desk (503-588-6213); easements shown on the Development Services utility map also limit placement. Front setback: Not published on the City's ADU page; the RS zone front setback for the main house applies unless SRC 700.007 says otherwise. Confirm with the Planners Desk (503-588-6213); a Class 1 Adjustment ($1,051, FY2027) is the route if a standard cannot be met. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None required for an ADU (City ADU page; SRC 700.007). State law bars ADU parking mandates - ORS 197A.425(1)(b), formerly ORS 197.312(5). 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. The City's HB 2001 FAQ states Salem's code already complied with the state ban on owner-occupancy requirements (ORS 197A.425, formerly 197.312(5)); the ADU may be rented long-term (30 days or more). 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 Salem is typically Not published by the City for ADUs; the ready-build plan set is described as expediting building review. Confirm current turnaround with the Permit Application Center (503-588-6256) before scheduling a build. Plan check: Building plan review is 65% of the building permit fee (FY2027 Fee Schedule); same-day or expedited review is $150/hour with a 2-hour minimum. No published turnaround for residential plan review. Pre-approved plans availability: Yes - one free City ready-build detached ADU plan set (under 600 sq ft) with a choice of slab or raised foundation and gable or shed roof, downloadable in English and Spanish; the City says it expedites building review. A gable roof needs a stamped truss package at submittal.
Average ADU rental income in Salem: 1-bedroom units rent for $1,100-$1,400/month, 2-bedroom units for $1,400-$1,800/month. Short-term rentals: No. SRC 700.006(b)(1) and (c)(1) (Ord. Expected ROI: About 4-8% gross rental yield before expenses at Sept 2026 median rents of $1,100 (1 BR) to $1,399 (2 BR) per month on a $170,000-$330,000 build; long-term tenancy only.
The minimum lot size for an ADU in Salem is No separate ADU minimum is published; the ADU must be accessory to a lawful detached single-family house (RS/RA house lots are at least 4,000 sq ft under the City's HB 2001 FAQ) and must fit the 75%-of-main-house cap. Confirm lot coverage with Planning. 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 Salem, a garage conversion typically costs $90,000-$160,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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