Research by DoINeedAPermit Research Team · Updated May 2026
The Short Answer
All ADUs in Camas require a building permit. However, Washington State law (RCW 36.70C.020) overrides many local restrictions, allowing ADUs in single-family zones without owner occupancy, parking waivers, and reduced setbacks — but the City of Camas still enforces its own lot-size and dimensional standards that can block proposals.
Camas adopted ADU regulations in 2024 to comply with Washington State's strong ADU mandate, but the city's interpretation remains more restrictive than some neighboring jurisdictions (e.g., Washougal, Troutdale OR). The key Camas angle: the city requires a minimum lot size of 6,000 square feet for a detached ADU and maintains a 15-foot interior side setback, whereas the state law technically permits ADUs on smaller lots if they fit other criteria. Camas also requires separate utility connections (or sub-metering) and a separate entrance, which are state-default rules but enforced strictly here. The city does NOT require owner occupancy of the primary dwelling after recent amendments aligning with RCW 36.70C.020, a major shift from prior practice. Plan review typically takes 4–6 weeks; the city uses an online portal (eGov) but also accepts over-the-counter intake. ADU permits are fast-tracked under state law, but Camas has experienced permit-processing delays due to staffing, so confirm the current review queue when you submit.

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

Camas ADU permits — the key details

Washington State law (RCW 36.70C.020) mandates that cities allow ADUs on single-family lots, but Camas has exercised local discretion to set qualifying thresholds. The city requires a minimum lot size of 6,000 square feet for a detached ADU, measured from the property line to property line (not adjusted for irregular shapes). This is the single largest gate-keeper rule in Camas code. A lot smaller than 6,000 sq ft may still qualify for a junior ADU (a smaller, attached unit sharing a wall with the main house) or a garage-conversion ADU if the garage is physically attached to the primary dwelling. The city explicitly allows ADUs without owner occupancy of the primary unit, removing a common barrier in older zoning. Setback requirements: detached ADUs must maintain a 15-foot interior side setback and a 25-foot rear setback from the property line; an attached ADU (above garage, converted garage, or junior ADU) must meet the main house's setbacks, typically 5 feet side and 25 feet rear in residential zones. These are measured from the ADU's exterior wall to the property line, not from the main house.

Utility separation is non-negotiable in Camas. Each ADU must have its own separate water and sewer connections, or the city will require a dual-meter or sub-metering system to track individual unit consumption. If the lot's sewer connection is already to code and the city allows it, you may argue for a single line with a meter split, but this must be approved in writing by the City of Camas Building Department and Public Works before you file. Electrical service must also be separate: the ADU gets its own meter and circuit panel (not a subpanel fed from the main house's service). This separation is mandated by National Electrical Code 705.12 and Washington State amendments, but Camas enforces it strictly; inspectors will reject the rough electrical if sub-feeds are discovered. Natural gas, if applicable, is handled on a case-by-case basis — the building department will specify during pre-application. A separate entrance is also required by Camas code: the ADU cannot share a door with the primary dwelling (though a shared breezeway or entry vestibule is sometimes permitted; ask during pre-application). Windows and doors must comply with IRC R310 (emergency egress): a bedroom in an ADU must have a window at least 24 inches wide, 36 inches tall, with an opening at least 20 sq ft (5.7 sq ft minimum sill height) and sill no more than 44 inches above the floor. This is tested during final framing and window inspections.

Parking is a gray area in Camas thanks to state law. RCW 36.70C.020(2)(a) prohibits cities from requiring off-street parking for ADUs, but Camas code still contains legacy parking language. The current city interpretation (confirmed in 2024 amendments) is that parking is not required for an ADU if the lot already provides parking for the primary dwelling. However, some staff have historically demanded a parking plan; clarify this in your pre-application meeting. If you are converting an existing garage into an ADU, the primary dwelling loses that garage parking space, and the city may require you to replace it with an open space on the lot; this is not always enforced but confirm. Setback violations on corner lots are common: if your lot is a corner lot (two frontages), one of those frontages triggers a "front setback" of 25 feet for an ADU, which consumes lot depth quickly. A 6,000 sq ft corner lot may have only 50 feet of usable depth after front and rear setbacks, leaving little room for a detached unit; measure carefully before designing.

Foundation and site-specific conditions are critical in Camas. The area sits in USGS seismic zone 2 (moderate earthquake risk), and frost depth is 12 inches in the Puget Sound area (Camas proper) but can reach 18–24 inches in the higher elevations east of town. Your engineer must specify frost-protected shallow foundation (FPSF per IRC R403.3) or a conventional footing below the frost depth; most detached ADUs use a full basement or a 24-inch conventional footing in Camas-proper, costing $8,000–$15,000 for a 600 sq ft unit. Soil boring and geotechnical report are often required by the city if foundation type is unclear; budget another $1,500–$2,500 for boring and engineer letter. Drainage and stormwater are also Camas requirements: if your ADU increases impervious surface (concrete driveway, foundation footprint), you may need a stormwater detention swale or rain garden; the Public Works review adds 2–3 weeks to the timeline and sometimes requires changes. Check with Public Works during pre-application about whether a bioswale is required.

The permit and inspection sequence in Camas follows a standard building-code path: (1) pre-application meeting with Building & Public Works (1 hour, free, strongly recommended), (2) submit complete plans (architectural, structural, electrical, plumbing, site plan with utilities and setbacks), (3) plan review (4–6 weeks typical; Camas queue is sometimes longer), (4) contractor mobilization after permit issuance, (5) foundation/footing inspection, (6) framing inspection, (7) rough trades inspection (MEP), (8) insulation & drywall inspection, (9) final building inspection, (10) utilities approval (water, sewer, electrical), (11) occupancy sign-off. Owner-builders are allowed for owner-occupied ADUs in Washington State and Camas does not restrict this, though the building department will ask you to sign an affidavit confirming owner occupancy. If you intend to rent out the ADU immediately, you must disclose this; it does not prevent permitting but triggers rental registration requirements with the City of Camas. Total timeline from pre-app to occupancy is 8–12 weeks with a cooperative inspector; add 4–8 weeks if plan revisions are required.

Three Camas accessory dwelling unit (adu) scenarios

Scenario A
Detached ADU on a 7,500 sq ft lot in Camas-proper (residential zone), no existing structures, 600 sq ft with separate utilities
This is a clean scenario that meets Camas's 6,000 sq ft minimum and allows a detached ADU. Lot dimensions: assume 75 ft x 100 ft. A 20-foot by 30-foot (600 sq ft) detached building can be sited 25 feet from the rear line and 15 feet from each interior side setback, leaving about 30 feet of usable rear depth and 45 feet of side-to-side width — plenty of room. Water, sewer, and electrical require separate connections: the city will require Public Works review of the sewer tap (usually $500–$1,500 in tap fees) and a separate water meter ($300–$600); electrical is a separate service entrance ($2,000–$3,500 including panel and meter). Site plan must show the primary dwelling, the ADU footprint, setbacks dimensioned, and utility runs from the house to the ADU. Frost depth is 12 inches in Camas-proper; a conventional footing below 24 inches (12-inch frost + 12-inch safety margin) costs $8,000–$12,000 for a 600 sq ft building. Stormwater: if the lot has adequate pervious area, no detention may be required; if impervious cover exceeds 35% of lot area, a rain garden or swale is added ($2,000–$4,000). Permit fee: approximately $2,500–$3,500 (based on valuation; 600 sq ft at ~$150/sq ft construction = $90,000 valuation, yielding a $2,000–$3,000 permit fee plus plan review). Total hard costs including permits, site work, utilities, and inspection: $20,000–$30,000 construction cost plus $3,500–$4,500 permit and utility fees. Timeline: pre-app (1 week), plan review (4–6 weeks), construction (8–10 weeks), inspections (3–4 weeks), occupancy: 4.5–5 months total.
Lot size: 7,500 sq ft (meets minimum) | Detached, separate utilities required | Frost depth 12 inches, 24-inch footing | Permit fee $2,500–$3,500 | Public Works/stormwater review | Utility tap/meter fees $800–$2,100 | Total hard costs $20,000–$30,000 construction + $4,500 fees
Scenario B
Garage conversion to junior ADU on a 5,500 sq ft lot (smaller lot, zoned single-family), existing attached garage, ~300 sq ft new unit above garage
A junior ADU (defined in Washington State law as an ADU up to 800 sq ft that shares a wall with the primary dwelling) can be allowed on lots smaller than 6,000 sq ft. Converting the existing attached garage and adding a second story above it creates a 300 sq ft unit; this meets the junior ADU definition. Setback requirement: since the ADU is attached to the primary dwelling, it inherits the primary dwelling's setbacks (typically 5 feet side, 25 feet rear for residential Camas zones). This is much easier than a detached ADU. Utilities: even though this is a conversion, the city still requires a separate water and sewer meter (or sub-meter with city approval) and a separate electrical service entrance; this is a surprise to many homeowners but Camas enforces it. If the primary house has a single sewer line to the main connection, you must run a separate line to the ADU or install a dual-meter at the main shutoff (approximately $1,200–$1,800 in plumbing). Separate entrance: the ADU must have its own access; this can be a door on the side of the building or an exterior stair to a second-story entrance. Parking: the primary house loses the garage's parking; Camas may or may not require replacement parking depending on how strictly the staff interprets the 2024 amendments; assume you will need to stripe or designate a parking space on the driveway. Egress: the upstairs unit must have windows meeting IRC R310 emergency egress. Foundation: no new foundation is required since you are building on the existing garage structure, but the engineer must certify that the existing foundation and floor framing can support the second story. Structural review (additional $1,500–$2,000 engineering). Permit fee: $2,000–$3,000 (smaller valuation than detached since it's a conversion/addition, not full new construction). Building permits, structural review, plumbing/electrical rough-in upgrades: $3,500–$5,000 total fees. Construction cost: $40,000–$60,000 (garage interior finish, second-story framing, MEP, finishes). Timeline: pre-app (1 week), structural engineering review (2–3 weeks), plan review (5–7 weeks), construction (10–12 weeks), final: 5–6 months.
Lot size: 5,500 sq ft (junior ADU permitted on lots <6,000 sq ft) | Attached garage conversion + second story | Separate water, sewer, electric required | Structural engineering $1,500–$2,000 | Permit fee $2,000–$3,000 | Utility modifications $1,200–$1,800 | Total hard costs $40,000–$60,000 construction + $4,500–$6,000 fees
Scenario C
Corner lot (8,000 sq ft, two frontages), detached ADU sited behind primary dwelling, owner plans to rent immediately (triggers rental registration)
Corner lots present a setback challenge: Camas code treats one of the two front-facing sides as a 'front setback' (25 feet) rather than a side setback (15 feet). A 100 ft x 80 ft corner lot (8,000 sq ft) has frontages on two streets. The primary house sits near one corner; a detached ADU sited toward the rear must maintain 25 feet from the street-facing property line (front setback), 15 feet from the interior side line, and 25 feet from the rear. This constraint means: if the lot runs 100 feet along the primary street and 80 feet deep, a 25-foot front setback eats 25% of depth; add 25 feet rear setback = 50 feet consumed, leaving 30 feet of usable depth. A 600 sq ft ADU at 20x30 feet fits, but just barely. Site plan must clearly label which property line is 'front' vs 'interior side'; errors here are a common reason for plan resubmission. Utilities are standard (separate water, sewer, electric). Stormwater review will focus on drainage toward the street and neighbor's lot; a swale may be required. Owner-builder allowed for owner-occupied ADU; if you plan to rent, you must file a rental registration with the City of Camas within 30 days of occupancy (no permit impact, but a separate administrative requirement). Rental tax (if applicable) is also owed. Rental registration is free but triggers annual city rental inspections (every 2 years or on complaint); this does not affect the building permit but affects long-term compliance. Permit fee: $2,500–$3,500. Utility and site work: $3,000–$5,000. Corner-lot survey may be recommended to confirm setbacks ($500–$1,000). Total: $6,000–$9,500 in hard costs plus $25,000–$35,000 construction. Timeline: pre-app (1 week), survey (2–3 weeks concurrent with plan prep), plan review (4–6 weeks), construction and inspections (4.5 months), rental registration post-occupancy: 5–6 months overall.
Lot size: 8,000 sq ft (meets minimum, corner lot) | Front setback 25 feet (street-facing), interior side 15 feet | Separate utilities required | Stormwater/drainage review likely | Rental registration required (free, triggers inspections) | Corner-lot survey recommended $500–$1,000 | Permit fee $2,500–$3,500 | Total fees $6,000–$9,500 + $25,000–$35,000 construction

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Washington State RCW 36.70C.020 vs. Camas local code: what overrides what

Washington State's ADU mandate (RCW 36.70C.020, effective January 2024) prohibits cities from requiring owner occupancy, on-site parking, or certain other restrictions. Camas amended its code in 2024 to nominally comply, but loopholes remain. The state law says cities can enforce their standard setback, height, and lot-coverage rules; Camas's 6,000 sq ft minimum lot size for detached ADUs and 15-foot interior side setback are legally defensible because they apply equally to primary dwellings. However, Camas's former owner-occupancy requirement was struck; you can now own the primary dwelling and rent both it and the ADU, or leave the primary vacant and rent the ADU — the city cannot object on occupancy grounds.

In practice, Camas staff apply the state law conservatively. If your proposal meets Camas's local thresholds (6,000 sq ft, setbacks, utilities), you are on firm legal ground, and the permit should issue. If you are below 6,000 sq ft but qualify for a junior ADU, state law does not override Camas's lot-size rule; junior ADUs are explicitly allowed in RCW 36.70C.020(2)(c) and are the workaround. Some Camas residents have challenged the 6,000 sq ft threshold as inconsistent with the spirit of state law, but no court has struck it yet. If you believe Camas is blocking a lawful ADU, consult a land-use attorney; the state Attorney General's Office can also be contacted for interpretation.

Parking is the most litigated aspect. RCW 36.70C.020(2)(a) says 'a city shall not require more than one parking space per dwelling unit for any dwelling unit on a lot where a principal dwelling unit is located.' In plain English, this means one space for the primary house, one space for the ADU. Camas code still references parking in legacy language, but the 2024 amendments align with this: one space per unit. If you are converting a garage (losing parking), you may be required to stripe a replacement space on the lot; Camas's position is that you must maintain parking for the primary unit. Push back if the city demands more; cite RCW 36.70C.020(2)(a) and request a written decision.

Pre-application meeting strategy and common rejection patterns in Camas

Camas's Building Department strongly encourages a pre-application meeting (one hour, free, no obligation). This is the single best investment you can make before design. Bring a site plan (aerial or sketch), dimensions, and your ADU concept (detached, attached, conversion). Ask the following: (1) Is my lot size (in sq ft) acceptable for the ADU type I want? (2) What are the exact front, side, and rear setbacks for my property (confirm with the assessor's zoning map if unclear)? (3) Will a separate water/sewer line or sub-meter satisfy the 'separate utility' requirement, or does the city insist on a second main connection? (4) Is a stormwater detention/infiltration feature required for my lot? (5) What is the current queue time for plan review (this varies; sometimes 4 weeks, sometimes 10 weeks depending on staffing)? Document the answers in writing (ask for an email summary).

Common rejection patterns: (1) Setback violations — most common on corner lots or irregularly shaped parcels; use a surveyor if your lot is not rectangular. (2) Lot-size misunderstanding — applicants underestimate the lot area or miscount square footage; confirm with the county assessor's record before design. (3) Utility plan inadequate — sketches showing water/sewer/electric but not meter locations or separation points; Camas requires dimensioned utility runs and a separate meter for each unit shown on the site plan. (4) Stormwater omission — especially if converting a garage or adding impervious surface; Public Works will flag this during circulation and cause a plan resubmission. (5) Egress window violations — ADU bedrooms missing IRC R310 windows; catch this before framing by reviewing window schedules with the building department during plan review. (6) Setback misinterpretation on corner lots — applicants confuse interior side with front setback; a title company abstract or survey clarifies which lines are street-facing.

The plan submission checklist Camas requires: (1) architectural plans (floor plan, elevations, sections) at 1/4-inch scale; (2) site plan (1/8-inch scale) showing lot lines, setbacks dimensioned, primary and ADU footprints, utility runs, parking, driveway; (3) electrical one-line diagram showing separate service to ADU; (4) plumbing schematic showing separate meter location; (5) foundation plan or structural details if full new construction; (6) energy code compliance statement or form. Incomplete submissions are bounced back; Camas's review clock does not start until the packet is complete. Budget time for revisions: a typical first submittal draws 5–15 comments, requiring a revised plan. Expect 2–3 revision cycles.

City of Camas Building Department
Camas City Hall, 316 3rd Ave, Camas, WA 98607
Phone: (360) 834-5505 ext. Building Permits | https://www.ci.camas.wa.us/permit-applications
Monday–Friday 8:00 AM – 5:00 PM PT

Common questions

Can I build an ADU on my 5,000 sq ft lot in Camas?

Not a detached ADU; Camas requires 6,000 sq ft for detached units. However, you can build a junior ADU (up to 800 sq ft, attached to the primary dwelling or above an existing garage) on a smaller lot. A junior ADU shares a wall with the main house and must still have separate water, sewer, and electrical service. Confirm with the Building Department in a pre-application meeting whether your lot configuration allows a junior ADU.

Do I need owner occupancy to build an ADU in Camas?

No. Washington State law (RCW 36.70C.020) prohibits owner-occupancy requirements, and Camas's 2024 code amendments removed this rule. You can build an ADU and rent both the primary dwelling and the ADU, or leave the primary vacant and rent only the ADU. The state law applies; Camas cannot block you on occupancy grounds.

How much does a Camas ADU permit cost?

Permit fees typically range from $2,000–$3,500 depending on the ADU's square footage and valuation. Separate utility connections (water meter, sewer tap, electrical service) add $2,000–$3,000 in utility fees and tap charges. Plan review and structural engineering (if required) add another $1,500–$2,000. Total permit and fee costs: $5,500–$8,500 before construction labor and materials.

Can I convert my garage into an ADU in Camas?

Yes. A garage conversion qualifies as a junior ADU if the new unit is attached to the primary dwelling and does not exceed 800 sq ft. Camas still requires separate water, sewer, and electrical connections (or sub-metering), plus a separate entrance and windows meeting emergency egress code (IRC R310). You will lose parking in the garage; Camas may require you to designate replacement parking on the driveway or lot. Budget $40,000–$60,000 for a garage conversion ADU including framing, MEP upgrades, and finishes.

What is the timeline for a Camas ADU permit and construction?

Pre-application meeting: 1 week. Plan preparation and structural review (if needed): 2–4 weeks. Plan review by the building department: 4–6 weeks (sometimes longer if the queue is full; confirm at pre-app). Construction and inspections: 8–12 weeks depending on scope. Total: 4.5–6 months from pre-app to occupancy. Delays are common if revisions are required or stormwater features need redesign.

Are there setback requirements for an ADU on a corner lot?

Yes. Corner lots have a front setback of 25 feet (on the street-facing side) and interior side setbacks of 15 feet (on the side not facing a public street). A detached ADU must maintain these setbacks from the property lines. This constraint can make corner lots tight; a 100 ft x 80 ft corner lot has limited usable depth. Work with a surveyor or the building department in pre-application to confirm which property line is 'front' and whether your ADU concept fits.

Can I use an owner-builder license to build my ADU in Camas?

Yes, if the ADU is owner-occupied. Washington State allows owner-builders for owner-occupied dwelling units, including ADUs. You must file an owner-builder affidavit with the permit application and sign that you will occupy the unit. If you plan to rent the ADU from day one, you must use a licensed contractor; owner-builder status is not allowed for rental properties.

What are separate utility connections, and why does Camas require them?

Separate utility connections mean the ADU has its own water meter, sewer line tap, and electrical service entrance rather than sub-feeds from the primary dwelling. Camas requires this to ensure the city can meter water use independently, track sewer discharge per unit (important for septic design and stormwater), and comply with electrical code (NEC 705.12). Even a small garage conversion needs a separate meter and panel. This adds $2,000–$3,000 in plumbing and electrical costs but is non-negotiable.

If I rent out my ADU, what else do I need to do besides getting a permit?

You must register the rental property with the City of Camas within 30 days of occupancy (rental registration is free). Camas also requires annual or biennial rental inspections; the city will schedule these to verify code compliance. Additionally, you may owe rental tax to the City and State of Washington; consult a tax professional or accountant. None of these post-permit requirements affect the building permit itself, but they are mandatory if you intend to rent.

What happens during the building inspection sequence for an ADU in Camas?

Inspections occur at: (1) foundation/footing (before concrete pour), (2) framing (walls and roof before sheathing), (3) rough trades (MEP before walls closed), (4) insulation and drywall, (5) final building (all work complete), (6) electrical final and utility approval (water/sewer sign-off). You must call ahead to schedule each inspection; the building department's response time is typically 1–3 business days. Missing an inspection appointment delays the permit; coordinate with your contractor to ensure inspectors have site access. The final occupancy sign-off is issued after the building inspector, electrical inspector, and utilities (water/sewer/gas) approve the unit.

Nearby cities & related guides

Accessory Dwelling Unit (ADU) Permits in Seattle, WA Accessory Dwelling Unit (ADU) Permits in Spokane, WA Accessory Dwelling Unit (ADU) Permits in Tacoma, WA
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 Camas Building Department before starting your project.

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