What happens if you skip the permit (and you needed one)
- Stop-work orders and fines: Covington building enforcement can issue a $500–$1,500 stop-work order if unpermitted work is discovered, plus required permit re-pull at double fee.
- Title defect and resale disaster: An unpermitted ADU must be disclosed on any future home sale; buyers and lenders routinely refuse financing until the unit is brought into compliance—remediation costs $8,000–$25,000.
- Insurance denial: Homeowner's and liability policies often exclude coverage for unpermitted structures; a claim for injury or damage on or in the ADU may be denied outright.
- Forced removal: Pierce County and Covington have enforcement power to order demolition of non-compliant ADUs; cost to remove and restore: $15,000–$40,000.
Covington ADU permits—the key details
Washington state law HB 2379 (effective 2019) and RCW 36.70A.696 mandate that cities allow at least one ADU per single-family lot and prohibit most local restrictions that were common before 2019. Covington's ordinance aligns with state law: it permits detached ADUs, attached ADUs, garage conversions, and junior ADUs on single-family-zoned land. Critically, Covington does not require owner-occupancy of the primary residence or the ADU—you can rent both out. The city also waives parking requirements for ADUs under 750 square feet and requires only one additional space (or allows on-street credit) for larger units. Setback requirements are 5 feet on sides and rear for detached ADUs (matching primary dwelling) and 0 feet for attached units or conversions. Maximum lot coverage is typically 35–40% when combining primary and ADU footprint; check with the city because recent amendments may have adjusted these caps.
You must file a complete building permit application with construction drawings (site plan, foundation, framing, utilities, MEP systems), a proof-of-intent form confirming intended use, and evidence of utility availability (water, sewer, electrical service must be adequate or upgraded). If your ADU requires a new sewer lateral or water line, expect an additional 2–4 weeks for utility coordination. The city's plan-review cycle typically runs 10–15 business days for initial review, then 5–7 days per resubmittal after markups. Covington does not have a formal 'ADU-fast-track' program like some California jurisdictions, but staff is relatively experienced in ADU projects and will not invent restrictions beyond code. Egress is critical: every bedroom must have a compliant emergency exit per IRC R310 (minimum 5.7 square feet, 24 inches wide, 36 inches tall, with accessible well if below-grade). A 500-square-foot one-bedroom detached ADU typically costs $4,000–$8,000 to permit; a 750-square-foot two-bedroom runs $6,000–$12,000.
Foundation requirements depend on ADU type and location. If your detached ADU sits on glacial till (common in west Covington, near Puget Sound lowlands) or alluvial soils (east side), the city may require a soils engineer's report if the lot slopes steeply or has poor drainage. Frost depth in Covington is 12 inches on the west side (lower elevation) and 30+ inches east of SR-161, so footing depth varies—most west-side detached ADUs can rest on 18-inch footings; east-side projects often need 36–42 inches. If the primary home already sits on a crawlspace or slab, a detached ADU on the same lot will likely use the same foundation style for consistency, but not mandatory. Attached ADUs (side or rear addition) must match or exceed the primary structure's foundation depth and tie in properly. A garage conversion to ADU requires underfloor venting per IRC R408 (or sealed crawlspace), new egress windows, and a separate utility meter or approved sub-metering. Expect $15,000–$35,000 for a detached foundation package (design, engineering, permits); a garage conversion may only need $3,000–$8,000 because footings already exist.
Utility separation is non-negotiable. Your ADU must have its own electrical meter and service panel (not a sub-panel fed from the primary home's main service—the city will flag that). Water and sewer can be one shared line with a sub-meter or separate laterals; Covington prefers sub-metering for transparency and code-enforcement clarity. If the lot uses well or septic, ADU feasibility depends on system capacity; wells require yield testing, septic requires a design engineer certification that two dwelling units fit within the system's treatment area. Impact fees for a two-bedroom ADU in Covington are roughly $2,500–$4,500 (roads, parks, schools); these are non-refundable and apply even if you own-build. Plan-review and permit fees (not impact) run $800–$2,000. If you need a grading or drainage plan, add $500–$1,500 for consultant review.
Owner-builder status simplifies timelines and cost in Washington: you may pull a permit as owner-builder if the ADU is on your primary residence and you occupy the primary home during construction. Owner-builders in Covington do not need a general contractor license but must schedule all required inspections (foundation, framing, rough MEP, insulation/drywall, final). If you hire a general contractor, they must be licensed by the state (WSDO) and you must verify they carry current liability insurance. Inspection timeline typically runs 4–6 weeks once construction starts, with a final sign-off that lets you obtain a Certificate of Occupancy. Many lenders will not finance an ADU until final inspection is complete; if you are selling the property with an ADU, the new owner often must obtain a new Certificate of Occupancy, which can delay closing by 2–3 weeks if final inspection has not yet occurred.
Three Covington accessory dwelling unit (adu) scenarios
Washington state law and how it overrides Covington local zoning
RCW 36.70A.696 and HB 2379 (effective January 1, 2019) are the backbone of ADU permitting in Washington. The state law mandates that all jurisdictions allow at least one ADU per single-family-zoned lot, prohibit owner-occupancy requirements, and allow both detached and attached units. Before 2019, Covington and other Pierce County cities could ban ADUs outright or impose strict owner-occupancy and size caps. Now they cannot. If you read Covington's current municipal code and see language that contradicts RCW 36.70A.696, the state law wins—the city ordinance is preempted. This is why Covington's ADU code is relatively permissive: the city council has chosen to align closely with state law rather than fight it. HB 2379 also requires jurisdictions to allow junior ADUs (units sharing utilities with the primary home, no full kitchen, under 700 sq ft) with even fewer restrictions. Some Pierce County neighbors like Enumclaw have pushed back against junior ADU provisions; Covington has accepted them. The practical effect: if your proposed ADU meets state law but seems to violate Covington code, request a state-law preemption analysis from the city planner. Staff usually recognizes this quickly and issues a permit.
Beyond state law, Washington also allows 'alternate ADU arrangements'—meaning the state does not require that every ADU be a separate structure with entirely separate systems. Covington's interpretation aligns with this: you can do a garage conversion, an attached addition, or a new detached building, and the city will not prefer one over another. The state also permits what's called a 'housing-affordable ADU,' which has income or rent restrictions; some jurisdictions offer reduced impact fees for affordable ADUs. Covington has not formally adopted an affordable-ADU fee waiver program (as of 2024), but if state law changes or if the city updates its ordinance, this could appear. Check with City Hall when you apply to see if new programs are in place. The state law also says jurisdictions cannot require ADUs to be the 'same size or architecture' as the primary dwelling—so your modern prefab one-bedroom ADU does not have to match a 1970s rambler. This opens design freedom.
One important caveat: state law allows cities to impose reasonable setback, lot-coverage, and height standards. Covington does impose these (5-foot side/rear setback for detached, 35–40% lot coverage), and these are legal limits you must respect. If your lot is too small to fit a compliant ADU (e.g., less than 0.15 acres with steep topography and full setback requirements), the city can deny your permit—not because of preemption, but because the lot itself cannot accommodate the unit lawfully. This is rare, but it happens. Scenario A and B above show lots that are large enough; Scenario C uses the existing garage footprint, which sidesteps the setback challenge altogether.
Glacial till, alluvial soil, frost depth, and Covington's foundation reality
Covington straddles two distinct soil zones separated roughly by SR-161 (the highway that runs north-south through town). West of SR-161 (lower elevation, closer to Puget Sound), the soils are glacial till—a mix of clay, silt, sand, and gravel deposited during the last ice age. Glacial till on the west side is often dense and well-draining when undisturbed, but it can be variable (dense clay lenses alternate with looser sand). Frost depth west of SR-161 is 12 inches. East of SR-161, soils transition to alluvial deposits (river-laid sediment) and volcanic soils (especially near the Deschutes River valley); frost depth is 30+ inches. This matters enormously for ADU foundation cost and depth. A detached ADU on a west-side Covington lot (Scenario A: North Hill, glacial till, 12-inch frost) needs 18-inch footings minimum (6 inches below frost line per IRC R403.1.4.1). An east-side ADU (Scenario B: near SR-161, alluvial/volcanic, 36-inch frost) needs 36–42-inch footings—nearly double the depth and double the concrete volume. This difference alone adds $3,000–$6,000 to foundation cost.
Many ADU builders underestimate frost depth and get stopped at footing inspection. If your site is east of SR-161 (or if you are uncertain), hire a soils engineer for $800–$1,500 to verify frost depth and bearing capacity. The engineer's report is required by Covington for any lot with slopes over 15% or any lot where existing homes show foundation issues (cracks, settling). If you skip the engineer and pour 18-inch footings on an east-side lot, the city inspector will flag it as non-compliant; you will have to underpin (dig deeper and add concrete)—a disaster that costs $8,000–$15,000 to fix and delays completion by 4–6 weeks. Covington building department staff know the frost-depth zones well and will warn you if your design is under-depth, but it is your responsibility to get this right during design, not during inspection.
Drainage is the second soil-related issue. West-side Covington has high water tables in winter (Puget Sound lowlands); some properties have perched water (groundwater sitting on a clay lens). If your detached ADU site shows signs of water (wetland vegetation, standing water, poor drainage), request a site-specific drainage analysis. East-side Covington near the Deschutes River can have alluvial soils with poor bearing capacity in wet conditions—a soils engineer must sign off before you pour footings. Neither zone is prohibitive for ADUs, but you must acknowledge the soils upfront or you risk costly delays. Covington does not require a standard geotechnical survey for every ADU, but the city will ask for one if the lot slopes over 20% or if there is evidence of water infiltration in the existing home.
Covington City Hall, Covington, WA 98313
Phone: (253) 931-3000 (main line; ask for Building Department or Building Services) | https://www.covingtonwa.gov (check for permits/building services link or contact city directly for online portal details)
Monday–Friday, 8:00 AM–5:00 PM (verify current hours by calling)
Common questions
Can I rent out both the primary home and the ADU in Covington, or do I have to occupy one of them?
No owner-occupancy requirement in Washington state or Covington code. RCW 36.70A.696 explicitly prohibits cities from requiring owner-occupancy. You can rent both units to tenants, or occupy the primary and rent the ADU, or vice versa. The only restriction: if you are an owner-builder (pulling the permit yourself without a general contractor license), you must occupy the primary home during construction; once construction is done and Certificate of Occupancy is issued, you are free to rent it out.
What is the difference between a junior ADU and a full ADU in Covington?
A junior ADU is limited to 700 square feet (or 400 sq ft in most other jurisdictions, but check Covington's current cap), cannot have a full kitchen (kitchenette with sink, microwave, and mini-fridge is allowed; no full stove or oven), and can share utilities with the primary home. A full ADU has no square-footage cap (typically 800–1,200 sq ft), must have a full kitchen and separate utilities (electrical meter, sub-metered water/sewer if shared laterals). Junior ADUs are cheaper and faster to permit and build; full ADUs offer more rental income and independence. Covington supports both. Scenario C shows a junior ADU (350 sq ft) which cost only $2,300 in permits versus Scenario A's full ADU (450 sq ft, $4,000+).
Do I need a separate electrical meter for my ADU, or can I use a sub-panel?
Covington building code and Washington state electrical code (adopting NEC) require a separate meter if the ADU is a separate legal dwelling unit (full ADU). A sub-panel fed from the primary home's service panel is not acceptable for a full ADU because it makes the units appear electrically dependent. For a junior ADU, a sub-panel is allowed and typical. If you install a sub-panel for a full ADU, the city will flag it at electrical inspection and require a meter upgrade ($1,500–$3,000). Plan ahead: confirm with the city and your electrician before pulling permits.
How long does Covington's ADU permit process take from application to Certificate of Occupancy?
Permit and plan review: 10–15 business days for initial review, 5–7 days per resubmittal (typically 1–2 rounds). Construction and inspections: 12–20 weeks depending on scope (detached new = longer; garage conversion = shorter). Total from permit application to final sign-off: 6–8 months for a simple project, 8–12 months for a complex detached build with utility upgrades. If utility work (new sewer/water lateral) is required, add 2–4 weeks.
Are there ADU impact fees in Covington, and how much will they cost?
Yes. Covington charges impact fees for roads, schools, parks, and utilities tied to new dwelling units. A full two-bedroom ADU currently costs roughly $2,500–$4,500 in impact fees (subject to annual adjustment). A junior ADU may qualify for a reduced rate (50% of full ADU, or ~$1,200–$2,000), but verify with the city because this varies. Impact fees are in addition to permit and plan-review fees. They are non-refundable even if you later abandon the project.
What if my lot is too small to fit a detached ADU due to setback requirements—can the city waive the setbacks?
Covington can grant a variance or administrative setback relief in limited cases, but it is not automatic. State law says cities can impose 'reasonable' setbacks; Covington's 5-foot side/rear setback for detached ADUs is considered reasonable. If your lot is under 0.15 acres and cannot accommodate both the primary home and a compliant detached ADU, consider a garage conversion (Scenario C) or an attached addition (Scenario B) instead. These have more flexible setback options. Contact the Covington planning division to discuss your specific lot before investing in design.
Can I use a prefabricated or modular ADU in Covington to speed up permitting and construction?
Yes. Modular ADUs (factory-built on a chassis, delivered and set on-site) are permitted in Washington and Covington, but they require HUD code certification or equivalent. The permit timeline does not necessarily shrink because Covington still requires full plan review, site-plan approval, and foundation/utility design. However, once permitting is done, construction time on-site drops dramatically (1–3 weeks vs. 16–20 weeks for stick-built). Modular ADUs are 10–15% more expensive upfront but save time and labor. Ask your modular supplier whether they have a relationship with Covington building staff—some manufacturers have 'approved' designs that sail through review.
If I build an ADU in Covington now, will it affect my property taxes or force a reassessment?
Yes, most likely. Adding a new dwelling unit (ADU) triggers a Washington state property-tax reassessment. The county assessor will assess the added value of the ADU and increase your property-tax bill. This is not an immediate Covington city permit issue, but it is a financial reality you should budget for. Consult a tax advisor or the Pierce County Assessor's office for an estimate before you commit to the ADU. Some jurisdictions (not Covington, but some others) offer tax deferrals or incentives for ADUs; check with the county assessor whether any apply.
What inspections will Covington require for my ADU, and in what order?
Full building permit inspections (in typical sequence): foundation (verify footing depth, rebar, concrete strength), framing (wall layout, roof structure, tie-ins), rough electrical/plumbing (wiring, boxes, pipe runs before walls close), insulation and drywall (thermal envelope, fire-rating), final (overall compliance, fixtures, egress windows, utilities). Utility inspections (separate from building): electrical meter sign-off (by city or utility company), water and sewer laterals (if new connections). Planning sign-off (land use compliance). You can schedule inspections through the city's portal or by phone. Each inspection typically takes 1–2 days and must be passed before you proceed to the next trade. Total inspection time (concurrent with construction): 4–6 weeks for a typical ADU.
Can I get financing or a construction loan for my Covington ADU project?
It depends on your lender and the ADU configuration. Banks and credit unions are increasingly willing to finance detached ADUs with separate utilities and clear title because the rental income is insurable and the unit is a separate legal dwelling. Lenders typically require a Certificate of Occupancy before releasing final funds. Owner-builder loans are harder to find; most lenders require a licensed general contractor. If you plan to refinance or sell the property with the ADU, ensure the ADU is fully permitted and inspected—unpermitted ADUs are a dealbreaker for buyers and their lenders. Start conversations with your lender early; they may have requirements (e.g., formal appraisal, insurance riders) that affect your timeline.