What happens if you skip the permit (and you needed one)
- Keizer Building Division can issue stop-work orders carrying a $500–$2,000 civil penalty plus mandatory re-pull of the permit at double the original fee.
- Unpermitted ADU conversion voids homeowner insurance on the structure; a claim for fire or water damage will be denied, leaving you liable for $50,000–$200,000+ in uninsured loss.
- Sale or refinance will trigger a lender title search; undisclosed unpermitted ADU can kill a loan ($0 proceeds until legalized) and require disclosure on MLS, reducing home value 10-20%.
- Neighbor complaint to Keizer Code Enforcement triggers inspection and forced removal or legalization; removal costs $15,000–$40,000 in labor and demolition.
Keizer ADU permits — the key details
Oregon state law (HB 2001, codified in ORS 197.303) grants by-right permission for one ADU per residential lot in cities and counties statewide. Keizer City Code Chapter 17.120 implements this mandate but adds local refinements: minimum lot size 5,000 sq ft (smaller lots in some overlays), setback compliance (15 ft front, 5 ft side, 10 ft rear for detached ADUs — same as primary house), and a maximum ADU size of 750 sq ft or 75% of primary dwelling sq ft, whichever is smaller. This ceiling is critical: a 1,500 sq ft house can support only a 750 sq ft ADU; a 900 sq ft house can support only a 675 sq ft ADU. Detached ADUs must meet IRC R401-R408 foundation requirements (12 in frost depth in the Willamette Valley, 30+ east of Salem). Attached ADUs (garage conversions, junior ADUs, above-garage units) must be structurally certified by a PE if they modify the primary structure's frame. The building permit application requires site plan (scaled lot diagram, building footprints, utility runs, parking, setbacks marked), electrical one-line diagram (showing sub-meter or separate service for the ADU), and complete building plans stamped by an Oregon-licensed architect or engineer if total structure square footage exceeds 5,000 sq ft or if modifications involve load-bearing walls.
Utilities are the second-biggest gotcha in Keizer ADU projects. Separate water and sewer connections are required by city code; you cannot share a single meter with the primary house unless the property already has a sub-meter or the city grants a hardship waiver (rare, $2,000–$5,000 application fee). Separate gas service is also standard, though the city may allow sharing if a valve isolates the ADU circuit. Electrical must be a separate panel and service entrance; sub-metering of a single service is acceptable only with written approval from Keizer Public Works. Most Keizer lots have municipal water and sewer, so separate connections typically cost $3,000–$8,000 (trenching, tap fees, meter set). If your property is on a septic system or well (common east of I-5), you must upgrade: a second bedroom ADU may require a 1,500 gallon secondary septic tank and drainfield, costing $8,000–$15,000 and triggering Marion County Health & Human Services approval in addition to Keizer's permit. The city will not issue a Certificate of Occupancy until utility inspections pass and the building is metered independently.
Parking exemptions have loosened statewide under Oregon law, but Keizer still expects documentation. If your ADU is within a half-mile of frequent transit (TriMet bus or Cherriots regional service), you are exempt from on-site parking requirements. If not, you must provide one off-street parking space on the property (in an easement, driveway, or designated lot area). If the lot cannot accommodate one space without violating setbacks or lot coverage, you may request a parking variance (filed with the ADU permit) or pay into the city's ADU parking in-lieu fee ($15,000–$25,000). This is rare in Keizer — most residential lots have room for one additional stall — but it's a common rejection point. The city's planning division will flag parking during pre-application review if it's in question; a phone call to Keizer Planning before design saves weeks of revision.
Inspection sequence for a detached ADU in Keizer typically includes: (1) foundation/site plan inspection (before concrete pour), (2) framing and rough mechanical/electrical (before drywall), (3) insulation and energy code compliance, (4) drywall and fire-separation (verify minimum 1-hour fire-wall separation if attached to primary dwelling), (5) final building inspection (all finishes, egress windows, smoke alarms), (6) electrical final and meter set, (7) water/sewer/gas final, and (8) planning final sign-off (verify parking, setbacks, no covenant violations). A typical detached ADU takes 3-4 inspection cycles over 10-14 weeks. Garage conversions move faster (6-10 weeks) if the structure is sound and no foundation work is needed. Owner-builders are allowed for owner-occupied primary dwellings in Oregon; you may pull the ADU permit yourself and schedule inspections, but a professional electrician and plumber are still required for their respective rough and final trades. If the ADU will be rented (not owner-occupied), you must disclose this to the city; some insurance and financing programs have stricter requirements for rental ADUs, but the permit process itself is identical.
Cost reality in Keizer: permit fee is $150–$400 (flat rate or sq ft-based, typically 1-1.5% of construction valuation), plan review is $800–$2,000 (charged per discipline: building, mechanical, electrical, plumbing), impact fees are $2,000–$5,000 (schools, parks, transportation), and utility-connection fees are $3,000–$8,000 (water tap, sewer tap, meter set). Total permit and gov-fee cost: $6,000–$15,000. Construction itself runs $150–$250 per sq ft for a 500-750 sq ft ADU (detached stick-built or modular), so a 700 sq ft detached ADU costs $105,000–$175,000 to build. Modular or prefab ADUs (available from companies like Blokable, Abodu, or Factory OS) cost $100,000–$180,000 and may expedite permitting if they have pre-approved plans. Financed ADUs can sometimes use construction loans ($0–$2,000 upfront) or home-equity lines; some lenders require the ADU permit to be in-hand before approval, others will commit based on a Letter of Intent from the city. Refinancing the primary home to fund an ADU is possible but requires disclosure of the ADU to the new lender; this can slow the refi if the lender views rental ADUs as a liability. A call to Keizer Planning (see contact card) during pre-design clarifies financing-approval requirements for your specific property.
Three Keizer accessory dwelling unit (adu) scenarios
Oregon state law pre-emption: why Keizer's local code matters less than you think
Oregon HB 2001 (2019, effective Jan 1 2020) and HB 2308 (2021) fundamentally changed ADU regulation in Oregon: local governments cannot prohibit ADUs by zoning, cannot require owner-occupancy, cannot impose minimum lot size larger than 5,000 sq ft, and cannot limit ADU size below 750 sq ft or 75% of the primary dwelling. This is a state mandate that overrides Keizer's local preferences. Keizer complied by amending Chapter 17.120 in 2020 to allow ADUs by right, matching the state floors. However, Keizer still enforces setbacks (local code Chapter 17.050), lot coverage (40% max in residential), and utility codes (Chapter 14) — these are consistent with state law but add local requirements. The key point: you do not need a Keizer City Council variance or conditional-use permit for an ADU. You do not need a neighborhood hearing. You file for a standard building permit, and the city reviews it under building code + the local amendments in Chapter 17.120. If Keizer tries to deny your ADU permit on the grounds that 'ADUs are not allowed in this zone' or 'you must be owner-occupied,' you have a state law claim; Oregon DLCD (Department of Land Conservation & Development) can override the local decision. This is rare in practice, but it's your backstop.
A second layer: Oregon's Qualified Applicant rule (ORS 197.303(10)). Effective 2022, if you submit a complete ADU application that meets the state baseline (lot size, setbacks, parking if required, utility separation), the city has 45 days to approve it or issue a detailed denial with specific code citations and a path to approval. This is a hard shot clock, unlike many states. If Keizer misses the deadline, the permit is deemed approved. In practice, Keizer planning staff will flag issues in a pre-application meeting (you can call, or file a pre-app for ~$200) and give you 2-3 weeks to revise before the formal permit is filed. This informal process avoids deadline misses. But if you file a complete application and Keizer issues a detailed denial at day 44, you have 10 days to cure the deficiency; if you do, the clock resets, and you get another 45 days. The timeline can stretch to 90 days in a back-and-forth, but Keizer's planning division is generally efficient and ADU-friendly.
Lastly, Oregon law pre-empts local parking requirements for ADUs in some cases: if the ADU is within a half-mile of a transit station or bus line, or if the lot is in an urban growth boundary with frequent transit, parking is waived. Keizer is the smallest city in Marion County and does not have heavy transit (no light rail or frequent bus service), so most ADUs still need one on-site space. However, Keizer does allow parking reductions or in-lieu fees if the lot truly cannot accommodate a space without a variance. The city's policy is pragmatic: call Planning during pre-design and ask if your lot qualifies for a parking waiver; if yes, you save $500–$1,000 in parking construction and a potential variance delay.
Septic systems, volcanic soil, and utility-separation complexity in rural/suburban Keizer
Keizer straddles two geographies: west of I-5 is the Willamette River alluvial plain (municipal water and sewer, 12 in frost depth, generally well-drained soil), and east of I-5 is higher elevation volcanic and glacial terrain (mixed septic/well systems, 30+ in frost depth, expansive clay pockets). An ADU on the west side of Keizer typically has straightforward utility extension (tap to the existing municipal lines and run separate meters). An ADU east of Keizer can be nightmarish if the property is on well and septic. For a well-and-septic ADU, Marion County Health & Human Services (MCHHS) must approve the septic system upgrade before Keizer will issue a building permit. A single junior ADU (500 sq ft, 1 bedroom) is often treated as adding one person to the septic system; a MCHHS designer will model the upgrade (typically a secondary 1,500 gallon tank and 500-1,000 sq ft additional drainfield). Cost: $8,000–$15,000 for design, permitting, and installation. Timeframe: MCHHS review takes 2-4 weeks, and you must have their septic design approval letter before Keizer will schedule the building foundation inspection. If the property is on a well (less common for ADUs in Keizer, but possible), you must confirm that the well has adequate yield (typically 10 gallons per minute for a 2-bedroom ADU) and that the water quality is potable (or treatable to potable standards). If the well is borderline or contaminated, you may be required to connect to a municipal line if available, or drill a new well (cost: $3,000–$5,000). The lesson: east of I-5 Keizer ADUs, get a septic and well evaluation BEFORE you design the ADU. A $500 pre-application call to MCHHS will clarify whether your property's septic/well is upgradeable or a dealbreaker.
Volcanic soil in East Keizer also triggers seismic design considerations. Oregon Residential Code (ORC, adopted statewide, equivalent to IBC 2021) requires post-and-beam or concrete piers on frost-proof footings (30+ in deep) for detached structures on volcanic or expansive soil. The 12 in frost depth on the west side (Willamette Valley) means a simpler slab-on-grade with thermal break; but east of Salem, you may need a full perimeter footing (frost-proofed to 30+ in) or piers under a floor frame. A PE will confirm the requirement for your specific soil and frost depth. This adds $1,000–$3,000 to foundation cost. If you're building a detached ADU east of Keizer, budget for a soil test ($200–$400, required by PE to confirm bearing capacity) and a foundation design (PE draws and calcs, $1,200–$1,800). West-side ADU projects rarely need a soil test (alluvial is stable and well-mapped).
Utility sub-metering and code compliance add another layer. Keizer code (Chapter 14.020) requires that each dwelling unit have an independent water meter and separate sewer service; sharing a single meter is not allowed. If your property's main water line is inadequate for two meters (undersized service entrance), the city may require an upgrade (typically a 1-1.5 in main, cost $2,000–$4,000). Gas can be sub-metered from a single service if the ADU has an isolating valve and separate circuit in the main meter; however, most Keizer gas providers (NW Natural Gas) prefer separate meters (two meters, ~$300–$500 each). Electrical is flexible: separate service panel and meter are required, but you can feed the ADU from a separate 60-amp subpanel off the primary house's main panel if space allows (saves $1,500–$2,000 in service-entrance upgrade). A licensed electrician and local electrical inspector will sign off on the sub-panel configuration. The utility-separation burden is highest on septic/well properties (septic alone adds 4-6 weeks and $8,000–$12,000) and lowest on west-side municipal-service properties (utilities alone run $4,000–$7,000 and 2-3 weeks).
930 Chemawa Road NE, Keizer, OR 97303
Phone: (503) 390-3700 (Keizer City Hall, ask for Building or Planning) | https://www.keizer.org (check 'Permits' or 'Building' section for online portal)
Monday-Friday 8:00 AM - 5:00 PM (verify on Keizer city website)
Common questions
Do I have to live in the primary house if I build an ADU in Keizer?
No. Oregon HB 2001 eliminated owner-occupancy requirements for either the primary house or ADU. You can own an investment property with both primary and ADU rented to tenants. However, lenders and insurers may impose stricter standards for rental ADUs (higher down payment, insurance disclosure, rate adjustment of 0.25-0.5%). Disclose the ADU rental intent to your lender and insurer early in the approval process.
Can I build an ADU on a lot smaller than 5,000 sq ft in Keizer?
No. Oregon state law set 5,000 sq ft (0.115 acre) as the minimum lot size for ADU allowance, and Keizer has adopted this as its local minimum in Chapter 17.120. Properties smaller than 5,000 sq ft cannot have an ADU. If your lot is borderline (e.g., 4,800 sq ft), you cannot proceed; if it is 5,100 sq ft, you're clear. Lot size is determined by the property deed and recorded survey; call Keizer Planning to confirm your lot size if you're uncertain.
What is the maximum size ADU allowed in Keizer?
The smaller of 750 sq ft or 75% of the primary dwelling's square footage. A primary house of 2,000 sq ft allows a 750 sq ft ADU (the cap). A primary house of 900 sq ft allows only a 675 sq ft ADU (75% rule is more restrictive). A primary house of 800 sq ft allows only a 600 sq ft ADU. Keizer measures the ADU size as gross living area (per Oregon Residential Code); covered porches and unheated garages don't count.
How long does it take to get an ADU permit in Keizer?
Typical timeline: 4 weeks for plan review (standard building department review), plus 2-4 weeks for pre-application feedback if requested, plus 8-12 weeks for construction and inspections. Total from concept to Certificate of Occupancy: 14-20 weeks. If the property is on septic (East Keizer), add 2-4 weeks for Marion County Health & Human Services approval. If the ADU is in a historic district (downtown Keizer), add 2-4 weeks for Keizer Historic Landmarks Commission review. Fast-track options exist but are not common for residential ADUs.
Can I build an ADU without a separate septic tank if my property has septic?
Almost never. A 1-bedroom junior ADU is typically treated as adding one person to the household; a standard 2-bedroom ADU is treated as adding two people. Marion County Health & Human Services will require an upgraded septic system (usually a secondary tank and expanded drainfield) to accommodate the additional load. The old septic alone is not sufficient. Budget 4-6 weeks and $8,000–$15,000 for the septic upgrade and MCHHS approval before Keizer will issue the building permit.
What if I want to use a prefab or modular ADU in Keizer?
Prefab and modular ADUs (Blokable, Abodu, Factory OS, etc.) are permitted in Keizer and may accelerate permitting if they have pre-approved plans or are certified by the state. You still need a local building permit and site-specific approval (foundation, utility connections, setbacks), but if the manufacturer's plans meet Oregon code, Keizer may issue a permit with minimal design review. Modular ADUs also allow faster construction (often 6-8 weeks from delivery to final inspection vs. 12-16 weeks for site-built). Cost is typically $100,000–$180,000 all-in, similar to site-built, but you compress the timeline.
Will my homeowner's insurance cover an unpermitted ADU?
No. An unpermitted ADU is considered unapproved construction and is excluded from most homeowner insurance policies. If a fire, water damage, or injury claim arises in the ADU, the insurer can deny the claim and leave you liable for the full loss ($50,000–$200,000+). Additionally, when you sell or refinance, the title search may flag the unpermitted structure, which can kill the loan or require you to disclose it on the Multiple Listing Service, reducing home value by 10-20%. Always permit the ADU before occupancy.
Can I be an owner-builder for an ADU in Keizer?
Yes, for owner-occupied primary-dwelling ADUs. Oregon law allows owner-builders (unlicensed homeowners) to pull permits and do work on their own property if they will occupy the primary dwelling. You cannot be an owner-builder if the ADU is rented or if the primary house is rented. As an owner-builder, you still must hire licensed trades (electrician, plumber, HVAC) for their respective rough and final inspections; you can do framing, drywall, finish work yourself. This saves $3,000–$8,000 in contractor labor and gives you oversight of the schedule, but it requires your availability and coordination. First-time owner-builders should expect a longer project timeline (8-12 weeks for a 600 sq ft ADU vs. 6-8 weeks with a general contractor).
Does Keizer require parking for an ADU?
In most cases, yes — one off-street parking space is required. The space can be in a driveway, designated lot corner, or paved easement; it does not need to be a separate garage. If your lot cannot fit one space without violating setbacks or lot-coverage rules, you may request a parking variance (filed with the ADU permit) or pay into the city's parking in-lieu fee ($15,000–$25,000). Parking exemptions apply if the ADU is within a half-mile of frequent transit (bus line with 30+ min headway), but Keizer has limited transit, so most properties need the space. Pre-application call to Keizer Planning can confirm if your lot is exempt.
What happens during the Keizer ADU building inspection sequence?
Typical sequence: (1) foundation/site plan (before concrete pour), (2) framing and rough electrical/mechanical (before drywall), (3) insulation and energy code (before drywall), (4) drywall and fire-separation (if attached ADU, 1-hour min. separation from primary house), (5) final building inspection (finishes, egress, smoke alarms), (6) electrical final and meter set, (7) sewer/water/gas final (utility company and city), (8) planning final sign-off (setbacks, parking, covenant compliance). Most detached ADUs pass 4-5 inspections over 10-14 weeks; garage conversions require fewer (3-4) and move faster (6-10 weeks). Inspector appointment scheduling is typically 1-2 weeks out; plan your construction sequence to allow buffer time between inspections. Missing an inspection due to incomplete work delays the next phase by 1-2 weeks. Hire an experienced general contractor or coordinate closely if owner-building.