Research by DoINeedAPermit Research Team · Updated May 2026
The Short Answer
Every ADU in Beaverton — detached new construction, garage conversion, junior ADU, or above-garage unit — requires a building permit. Oregon state law (ORS 197.314) overrides local zoning restrictions, but Beaverton still requires full plan review, building permits, and inspections.
Beaverton adopted a proactive ADU ordinance (BMC 60) that aligns with Oregon's 2019 state ADU law, but the city retains authority over site design, building code compliance, and utility connections. Unlike some Oregon cities that have lagged behind state law, Beaverton's Building Department actively processes ADU applications and has a track record of approving them without forced owner-occupancy clauses (as prohibited by ORS 197.314). The key Beaverton-specific rule: detached ADUs on residential lots under 5,000 sq ft face stricter setback enforcement (15 feet to rear, 7.5 feet to side) than some neighboring cities like Tigard, where minimums are more lenient. If your lot is in the Beaverton-Hillsdale Highway corridor or near transit, additional parking exemptions may apply — Beaverton's code explicitly waives ADU parking if the lot is within a half-mile of a MAX station or frequent-transit zone, a rare plus among Oregon suburbs. Plan review typically runs 4–8 weeks; if your application is complete, the city aims for a 60-day turnaround per state shot-clock rules, though utility coordination (especially sewer main access) can add time.

What happens if you skip the permit (and you needed one)

Beaverton ADU permits — the key details

Oregon state law (ORS 197.314 and OAR 660-033-0135), enacted in 2019 and amended through 2023, mandates that cities allow ADUs on residential lots and prohibits owner-occupancy requirements. Beaverton's local code (BMC 60.05.060) implements this by allowing detached ADUs, attached ADUs (junior ADUs), garage conversions, and above-garage units on any lot zoned residential — R5, R7, R9.5, R15. The city cannot require the primary residence to be owner-occupied for an ADU to be permitted, and cannot prohibit short-term rental of the ADU (though HOAs and deeds of trust may still restrict use). Setback minimums are defined in BMC 60.05.075: detached ADUs must be 15 feet from rear property lines, 7.5 feet from side lines (vs. primary house setbacks of 25 feet/10 feet). If your lot is under 5,000 sq ft, these setbacks can squeeze a detached unit into a narrow footprint — the city's planning staff can confirm feasibility pre-application, a courtesy most Oregon suburbs don't offer. IRC R310.1 governs egress: every habitable room (bedroom, living room) must have a door or window sized at least 5 sq ft (3 ft wide min, 24 in. tall min) that opens directly outside or to a common hallway. Garage conversions must include two egress windows or a door + window pair, which often requires enlarging existing openings — a $2,000–$5,000 framing upgrade.

Utilities and connections are the second-most common permit hang-up in Beaverton ADUs. The city requires a separate meter (electric and gas) or a sub-metered arrangement approved by the utility (Pacific Power, NW Natural). Sewer is the real choke point: if your primary house connects to the city main, an ADU on the same lot typically feeds into the same service line, but the city sanitary engineer must confirm the main is sized for two units (6-inch standard; 4-inch is borderline and may require upsize). Water is less restrictive. Septic systems (found on some rural-zoned Beaverton fringe lots) add complexity: state law (OAR 690-240) limits one dwelling per absorption area, which can block detached ADUs on septic unless a second system is installed — $20,000–$35,000 cost. If the main house is served by city sewer and you want a detached ADU, call Beaverton Public Works at the address below to request a sewer capacity letter before you buy plans; rejection at this stage saves $5,000–$8,000 in failed plan review.

Fire and life safety inspections are triggered by the ADU's square footage and proximity to the primary house. If the detached ADU is over 800 sq ft, Beaverton enforces automatic fire sprinklers throughout both the ADU and the primary residence (OBC 903.2, which Beaverton adopts). Many homeowners are surprised by this: a detached 900 sq ft ADU pulls a sprinkler requirement for the whole lot. Underground-sprinklered systems cost $8,000–$15,000 installed; hardwired fire alarm systems alone run $1,500–$3,000. If your detached ADU is under 800 sq ft, only the ADU requires a fire-extinguisher cabinet and smoke alarms. Egress windows must also meet IRC R312 tempered-glass or emergency-opening bar rules, which rejects sliding sash windows — you'll need casement or hopper-style windows, adding $500–$1,500 per opening. Attached junior ADUs (≤860 sq ft by ORS 197.314) sidestep the sprinkler rule if the primary house already has them, but plan review still verifies fire rating between units (1-hour if interior separation; 0-hour acceptable under Oregon amendments).

Beaverton's permit fee structure: ADUs are charged on a tiered valuation model. Detached new-build ADUs (600–1,000 sq ft) typically appraise at $80–$120/sq ft for permitting purposes, yielding a permit base fee of $800–$1,200, plus plan-review charges of $500–$2,000 depending on complexity (sewer extension, setback variance, sprinkler system). A garage conversion runs lower — $400–$800 base, since structural review is lighter. Impact fees (school, transportation, stormwater) apply to all ADUs and add $2,500–$6,000 total. Full cost (permit + plan review + impact fees) ranges $3,500–$10,000 for a straightforward detached ADU, up to $15,000 if sewer main extension is needed. Beaverton publishes a fee schedule online (search 'Beaverton ADU permit fee schedule') updated annually. Unlike some Oregon cities that have frozen or waived ADU fees to encourage housing, Beaverton has not; fees are applied consistently but are lower than Portland's. Pre-application consultations are free and strongly recommended — the planning staff can flag setback or utility conflicts before you pay for full plan review.

Timeline and plan-review workflow: Beaverton targets a 60-day permit issuance from a complete application (ORS 227.178 shot clock). In practice, ADU applications with typical scope (detached, under 900 sq ft, no variances needed) issue in 4–6 weeks. Applications requiring sewer-capacity studies, setback adjustments, or fire-code interpretation take 8–12 weeks. Once the permit is issued, inspections follow the standard sequence: foundation (before concrete pour), framing (before sheathing), rough trades (electrical, plumbing, HVAC), insulation, drywall, final building. For a detached ADU, add a separate planning inspection (site coverage, parking compliance) and utility sign-off. Total construction-to-certificate-of-occupancy timeline is typically 12–16 weeks for an ADU shell, longer if interior finishes require special inspection (commercial-grade kitchen for rental income, for example). Owner-builders are permitted in Beaverton for ADUs if the primary residence is owner-occupied, though the permittee still must pass an IRC trade exam and carry general liability insurance ($1,000–$2,000/year for that rider).

Three Beaverton accessory dwelling unit (adu) scenarios

Scenario A
Detached 750 sq ft ADU, rear of 6,800 sq ft lot, West Hills neighborhood, no sewer extension needed
You own a 0.156-acre West Hills home with city sewer and water already on-site. You want a detached 750 sq ft, one-bedroom ADU 20 feet from the rear property line (compliant with Beaverton's 15-foot minimum). The lot is over 5,000 sq ft, so setback relief is not needed. Sewer main runs under the street in front of your house; Public Works confirms it's a 6-inch line with capacity for two units. At 750 sq ft, your ADU is below the 800 sq ft sprinkler threshold, so only the ADU itself requires a fire-extinguisher cabinet and hardwired smoke alarms (no whole-lot sprinkler system). Your architect prepares plans showing compliant egress (one window per room, 5+ sq ft, tempered glass), septic-free because you're on city sewer, and a separate electric/gas meter on the east side of the ADU. Plan review is straightforward: 4–5 weeks. Base permit fee is $950 (valuation $75K × 1.3% rate), plan-review adder is $800, impact fees total $3,200 (schools, transportation). Total upfront cost: $4,950 in fees, plus your architect/engineer plans ($2,500–$4,000), plus construction ($80–$100/sq ft = $60,000–$75,000 hard costs). Inspections: foundation, framing, rough trades, insulation, drywall, final, planning sign-off. Timeline to CO: 14–16 weeks from permit issuance, assuming no change orders.
Permit required | Detached, ≤800 sq ft (no whole-lot sprinklers) | Sewer capacity confirmed | Setback compliant (20 ft rear) | Base permit $950 + plan review $800 + impact fees $3,200 = $4,950 municipal fees | Construction $60K–$75K
Scenario B
Garage conversion to junior ADU (700 sq ft), Hillsboro Road corridor, existing two-car garage, MAX-adjacent parcel
Your 1970s bungalow sits 0.3 miles from the Beaverton Central MAX station on Hillsboro Road. You convert an existing two-car garage into a junior ADU (attached unit, ≤860 sq ft per ORS 197.314). Because your lot is within the half-mile MAX-service zone, Beaverton's code (BMC 60.05.090) explicitly waives parking requirements for ADUs in transit corridors. This is a major Beaverton advantage vs. suburban competitors like Lake Oswego or Sherwood, where ADU parking mandates can kill the economics. The garage has a 12-foot ceiling, good for a 700 sq ft layout. Since it's an interior conversion, egress is trickier: IRC R310 requires two independent means of egress. You add a new door to the side yard (7.5-foot setback clears your property line) and retain the existing garage door as a second exit — code-compliant. Fire rating between the ADU and primary house: Oregon's adoption allows a 0-hour rating for attached ADUs ≤860 sq ft, so you don't need a formal 1-hour fire wall; a standard drywall partition suffices. Utility: the ADU taps into the primary house's electrical and plumbing with a separate sub-meter (Pacific Power approves a $300–$600 retrofit). Sewer uses the existing main without extension. Plan review runs 3–4 weeks because the scope is small. Permit fee is $600 (lower valuation for conversion), plan review is $500, impact fees are $1,800 (transit location may lower some fees). Total: $2,900 municipal fees. Construction cost is $50–$70/sq ft because you're not pouring a new foundation ($35K–$50K hard cost). No sprinkler system required. Inspections: framing, rough trades, insulation, drywall, final, planning. Timeline: 10–12 weeks from permit to CO.
Permit required for garage conversion | Junior ADU attached ≤860 sq ft | Parking waived (MAX-adjacent, half-mile transit zone) | No whole-lot sprinkler system | Fire rating 0-hour (Oregon allowance) | Base permit $600 + plan review $500 + impact fees $1,800 = $2,900 municipal fees | Construction $35K–$50K
Scenario C
Detached 900 sq ft ADU, 4,200 sq ft lot, east Beaverton (expanded frost depth 30 inches), sewer main extension required
You own a 4,200 sq ft lot (below Beaverton's 5,000 sq ft 'preferred' size) in east Beaverton near Aloha, in a Zone 5B climate with 30-inch frost depth. You want a detached, fully self-contained 900 sq ft, two-bedroom ADU. Three complications: (1) the lot is tight, so your 900 sq ft ADU only clears rear setback (15 feet) by 2 feet — you need a site plan from a surveyor ($800–$1,200) and a setback variance review, adding 2–3 weeks to plan review; (2) at 900 sq ft, the ADU exceeds the 800 sq ft sprinkler trigger, so you must install an underground sprinkler system serving both the primary house and ADU (cost $10,000–$14,000 hard); (3) the existing sewer service is a 4-inch private line shared with a neighbor — Public Works determines it cannot be upsize without a formal extension to the city 6-inch main, requiring a $12,000–$18,000 underground trenching project (you may need the neighbor's easement). Plan review jumps to 8–10 weeks due to the sewer study, setback analysis, and sprinkler engineering. Permit fee is $1,100 (higher valuation, larger unit), plan review is $2,500 (complex sewer scope), impact fees are $4,100 (east zone rates). Total municipal: $7,700. Frost depth: your foundation must go 30 inches (vs. 12 inches in western Beaverton), adding frost-protected shallow foundation (FPSF) design cost ($1,500–$2,000 engineering) and deeper excavation ($2,000–$3,000 labor/materials). Hard construction cost rises to $90–$110/sq ft due to sprinkler system and sewer extension ($81,000–$99,000 total hard cost). Inspections include sewer inspection, foundation (deeper), framing, trades, sprinkler rough-in, final. Timeline: 16–20 weeks from permit to CO, assuming no change orders.
Permit required | Detached 900 sq ft (triggers whole-lot sprinkler requirement) | Setback variance needed (2 ft relief on rear) | Sewer main extension required (4-inch to 6-inch) | 30-inch frost depth (FPSF design) | Base permit $1,100 + plan review $2,500 + impact fees $4,100 = $7,700 municipal fees | Hard construction $81K–$99K | Total project $100K–$125K

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Beaverton's sewer main and utility coordination — the biggest bottleneck

Sewer capacity is the single largest delay and cost factor in Beaverton ADU permitting. Unlike some cities where ADU sewers are rubber-stamped, Beaverton Public Works requires a formal capacity letter for every ADU application. If your primary house connects to a 4-inch city main, that line was typically sized in the 1970s–1990s for single-family service; an ADU doubles the load. A 4-inch line is marginal at best, and most lines require upsize to 6-inch. If your property is the downstream end of a 4-inch run, the Public Works engineer may require a full main extension from a larger trunk line (often blocks or even a mile away), costing $15,000–$25,000 and adding 6–8 weeks to permitting. In contrast, private septic systems (rare in Beaverton proper but found in unincorporated south Beaverton) face a different roadblock: Oregon's DEQ rule (OAR 690-240-0060) generally limits one dwelling per septic absorption field. A second septic system for the ADU costs $18,000–$35,000 and requires a soils test, DEQ approval, and a separate drain field — only feasible on lots 2+ acres. Call Beaverton Public Works (see contact card below) before finalizing a detached ADU design. Request a sewer capacity letter; if you get a denial or a notice requiring main extension, you've saved $8,000 in failed plan review and can pivot to a junior ADU or garage conversion instead (which use the existing main without extension).

Water is less restrictive in Beaverton. City water is assumed infinite; meter upsize from a 5/8-inch to 3/4-inch or 1-inch line is standard for ADUs and costs $500–$1,500 in materials and labor. Gas (NW Natural) is similar: a second meter is routine and has no capacity gate. Electrical is the easiest: Pacific Power approves sub-metered ADUs (a sub-panel fed from the primary house service) or separate meters without friction; upgrading service from 100 amps to 200 amps (common in older homes) costs $1,500–$3,000. Stormwater, however, is tightening in Beaverton due to MS4 discharge rules. If your lot currently has no stormwater detention and you add an impervious ADU (or you pave parking), Beaverton stormwater engineering may require a rain garden or detention vault ($3,000–$8,000). Check the city's stormwater atlas (online) to see if your lot triggers this; if you're in a designated TMDL (Total Maximum Daily Load) basin, plan for the cost.

Utility coordination sequence: (1) Call Public Works for sewer letter (1 week turnaround, free). (2) If denied or conditional, adjust design (drop to junior ADU or request easement). (3) File permit with utility letters attached. (4) Plan review begins; city coordinates with utilities during review (2–3 weeks). (5) Once permit is issued, call Pacific Power, NW Natural, and city water/sewer to schedule service drops (usually 4–6 weeks lead). (6) Foundation is poured after utilities are marked; electric/gas/water meter shanties are installed during framing. Sewer lateral inspection happens at rough-in stage. Missing this sequence — e.g., breaking ground before utility coordination — is the #1 stop-work trigger in Beaverton.

Fire sprinklers, egress, and the cost surprise for larger ADUs

Beaverton enforces OBC 903.2 (fire sprinklers) for residential buildings over 5,000 sq ft OR for individual dwelling units over 800 sq ft. Most ADU owners see the 800 sq ft threshold and assume they're safe — then discover that the threshold applies to TOTAL occupancy on the lot if the ADU and primary house are on the same parcel. Specifically, if your detached ADU is 900 sq ft and your primary house is 3,000 sq ft, the city calculates total occupancy as 3,900 sq ft, which exceeds 5,000 sq ft occupancy... wait, that's under the threshold. Let me clarify: the rule is 800 sq ft per dwelling unit. A detached 900 sq ft ADU triggers sprinkler requirement for the ENTIRE detached ADU (not the primary house) because the ADU alone exceeds 800 sq ft. If the primary house is over 3,500 sq ft, it also triggers independent sprinkler requirement for that unit (but that's a separate rule). In practical terms: detached ADU ≤800 sq ft = fire extinguisher + alarms only. Detached ADU ≥801 sq ft = underground sprinkler system throughout the ADU, costing $8,000–$14,000 fully installed (pump, underground laterals, heads, backflow preventer, permit from sprinkler contractor). This single requirement kills economics on ADUs sized 850–1,000 sq ft in Beaverton; most builders cap ADUs at 790 sq ft to avoid the sprinkler trigger. Junior ADUs (attached, ≤860 sq ft) are exempt if the primary house already has sprinklers, which shifts the incentive toward conversions and attached units.

Egress is the second financial surprise. IRC R310 requires at least one operable window or door (5+ sq ft effective opening, 3 feet wide minimum, 24 inches tall minimum) in every habitable room. For a bedroom, the egress window must be sized to allow rescue; for a living room, a standard door suffices. Beaverton code (BMC 60.05.080) adds a local wrinkle: egress windows must have a sill height no higher than 44 inches above the floor (to allow a child or elderly person to exit safely). Older garage-conversion ADUs often fail this: a standard single-hung window has a sill at 36–40 inches, which passes; but if you use sliding glass or a high transom, you must retrofit. Enlarging an existing opening to 5 sq ft (e.g., from a 2×3 window to a 3×5 door or hopper window) requires structural header analysis, often demanding a beam upsize, adding $2,000–$4,000 in framing. Many Beaverton ADU applications come back in plan review with an egress deficiency note, forcing a design revision and a 2-week delay. Pro tip: hire a designer or architect who has successfully permitted ADUs in Beaverton (not just residential remodels) to avoid this rework.

Sprinkler and egress costs compound. A 900 sq ft detached ADU with two bedrooms needs two egress windows (one per bedroom), likely requiring enlargement at $2,000–$4,000 each, plus a sprinkler system at $10,000–$14,000, totaling $14,000–$22,000 in code-driven costs before finishes or structure. This is why Beaverton ADUs in the 750–790 sq ft range are the economic sweet spot: they duck the sprinkler trigger, single-bedroom layouts need only one egress window (less enlargement cost), and the total soft cost stays under $8,000.

City of Beaverton Building Department
4755 SW Griffith Dr, Beaverton, OR 97005
Phone: (503) 526-2222 | https://www.beaverton.gov/permits-licenses/permits
Monday–Friday, 8:00 AM–5:00 PM; closed weekends and city holidays

Common questions

Does Oregon law really override Beaverton's zoning and let me build an ADU without owner-occupancy?

Yes. ORS 197.314 (2019) and ORS 197.314–197.319 (2023 amendments) mandate that cities allow ADUs and prohibit owner-occupancy requirements, deed restrictions, or HOA bans. Beaverton's BMC 60 implements this: you can rent the ADU to a tenant without living on-site. HOAs and existing deed restrictions may still prohibit rental; check your CC&Rs. Owner-occupancy of the primary house is NOT required by state law or Beaverton code, though some lenders (FHA, VA) still prefer owner-occupancy for financing purposes.

What if my lot is under 5,000 sq ft? Will Beaverton reject my ADU application?

No. Beaverton allows ADUs on residential lots of any size ≥2,000 sq ft (per BMC 60.05.040). Smaller lots face tighter setbacks (15 feet rear, 7.5 feet side), so a detached ADU may need to be smaller or reconfigured, but outright rejection due to lot size alone is rare. The city's pre-application consultation is free and helpful for tight-lot feasibility checks.

Do I need owner-builder experience or a contractor's license to build an ADU in Beaverton?

If you are the owner-occupant of the primary residence and the ADU is owner-occupied (or rented), you can file as an owner-builder. You'll need to pass an IRC trade exam ($100–$200), carry general liability insurance ($1,000–$2,000/year), and hire licensed contractors for electrical, plumbing, and mechanical work (you can do framing, drywall, finishes). If you are not the property owner or the primary house is not owner-occupied, you must hire a licensed GC.

What is the 'junior ADU' and how is it different from a detached ADU in Beaverton?

A junior ADU is an attached unit carved from the primary house (e.g., in-law suite) or converted from a garage, up to 860 sq ft per ORS 197.314. It's exempt from sprinkler requirements if ≤860 sq ft and the primary house has them. Junior ADUs avoid utility extension costs and sewer-capacity delays because they use existing mains. Detached ADUs are standalone structures and face stricter utility and fire-code reviews. Junior ADUs are often faster and cheaper to permit.

My lot has septic, not city sewer. Can I put a detached ADU on it?

Generally no, unless you install a second septic system. Oregon DEQ (OAR 690-240) limits one dwelling per absorption field. Beaverton has few septic lots (mostly unincorporated fringe), but if yours is septic, a second system costs $18,000–$35,000 and requires soils test, DEQ design, and local approval. A junior ADU, however, can use the primary septic if the system is sized for two units; have your septic pumper and an engineer assess capacity first.

How long does a typical ADU permit take in Beaverton, and what can delay it?

Straightforward applications (detached ≤800 sq ft, no sewer extension, compliant setbacks) issue in 4–6 weeks. Oregon's 60-day shot clock (ORS 227.178) applies. Common delays: (1) sewer capacity letter (1 week) plus main extension design (4–6 weeks if required), (2) setback variance or Historic District review (2–3 weeks extra), (3) incomplete plans (returned for revisions, 1–2 weeks per round). Complex ADUs (sewer main extension, sprinkler design, setback variance) take 10–14 weeks. Submit a complete application (plans, utility letters, site plan, design narrative) the first time to avoid delays.

Are there pre-approved ADU plans I can use to speed up permitting in Beaverton?

Oregon has not published state-level pre-approved ADU plans like California (SB 9). However, some plan services (e.g., ADU.com, Blokable) offer designs that comply with Oregon code; check that they reference ORS 197.314, OBC (Oregon Building Code, 2020 edition, which Beaverton adopts), and Beaverton's local amendments (BMC 60). Even 'pre-approved' plans still require Beaverton plan review and utility coordination, so savings are modest (maybe 1–2 weeks faster). Custom design by a local architect familiar with Beaverton's sewer and setback rules is often faster than adapting a template.

If I have an HOA, can it block my ADU even though state law allows it?

Not for the basic right to build. ORS 197.314 preempts HOA zoning rules. However, HOAs can restrict rental, parking, exterior appearance, or landlord/tenant rules within limits; check your CC&Rs. Some HOAs have already updated bylaws to allow ADUs; others haven't. If your HOA's CC&Rs ban ADUs or rental, consult an Oregon real estate attorney — there is emerging case law on preemption, and your rights may exceed what the HOA claims.

What is Beaverton's parking requirement for an ADU?

Beaverton requires 1 parking space for a studio/one-bedroom ADU, 2 spaces for a two-bedroom (BMC 60.05.090). However, if your lot is within a half-mile of a MAX station or in a frequent-transit zone, parking is waived. The city's transit-overlay map is online; check it before design. If parking is required but can't fit on your lot, you may request a waiver through variance (harder path) or land a variance through a transit-corridor exemption (if applicable).

Do I need to notify my neighbors before filing for an ADU permit in Beaverton?

Beaverton does not require neighbor notification pre-filing. However, after you file, the city mails a notice to neighbors (free service for $30–$50 filing). If neighbors object (rare for ADUs, common for multi-unit), they can request a Type B decision (extra hearing) instead of a Type A (administrative approval). Public hearing is required for ADUs that don't meet code (e.g., oversized, setback variance). Most Beaverton ADUs proceed Type A without hearing.

Nearby cities & related guides

Accessory Dwelling Unit (ADU) Permits in Portland, OR Accessory Dwelling Unit (ADU) Permits in Salem, OR Accessory Dwelling Unit (ADU) Permits in Eugene, OR
Disclaimer: This guide is based on research conducted in May 2026 using publicly available sources. Always verify current accessory dwelling unit (adu) permit requirements with the City of Beaverton Building Department before starting your project.

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