Bolthole Index

Washington County, Oregon

Zoning, building permits and septic rules in Banks, Oregon

The City of Banks, Oregon, in Washington County, adopts its own zoning code and limits land use inside city limits to what each zone permits1. Septic permits for homes without public sewer come from Washington County Environmental Health2. We could not confirm who issues residential building permits inside Banks, so ask the city office before you plan a build.

At a glance

Zoning
Yes. Banks sets its own zones inside city limits1
Zoning districts
RE, LDR, MDR-L, MDR-H, HDR and MU3
Building permit
Oregon requires permits for new construction; which office issues them in Banks is unconfirmed4
Septic
Washington County Environmental Health, for homes not on public sewer2
Manufactured homes
Allowed on individual lots in RE, LDR, MDR-L and MDR-H; not in HDR or MU5
Accessory dwelling
One ADU per lot6
Owner-builder
Oregon's owner-built exemption covers only ceiling heights, room sizes and temperature requirements7
Wells
A landowner well permit and bond are required statewide8

Who to call

Planning & zoning

City of Banks Planning Services

Land use applications, the Comprehensive Plan and the Development Code inside Banks city limits

503-324-5112

13680 NW Main Street, Banks, Oregon 97106

Septic permits

Washington County Environmental Health (Onsite Sewage Program)

Septic system permits for households not served by public sewer

503-846-8722

[email protected]

Also useful

City of Banks Public Works / Water

City water service and the city's posted water supply moratorium resolutions

503-324-5112

13680 NW Main Street, Banks, OR 97106

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

Going off-grid in Banks means bringing your own water and power. The kit we’d start with:

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Does Banks, Oregon have zoning?

Yes. All land inside the City of Banks is placed in one of the city's land use zones, and the city limits land use to what the zone permits1. The residential districts are RE, LDR, MDR-L, MDR-H and HDR, plus the MU district3. Washington County's zoning applies to unincorporated land, not to property inside a city, and the county says cities regulate land use within their own boundaries9.

For homes, the details depend on the district. Manufactured homes on individual lots are permitted in RE, LDR, MDR-L and MDR-H and not permitted in HDR or MU5. Banks allows one accessory dwelling unit per lot, either inside the main house or detached6. We could not confirm Banks rules for RVs, tiny homes or minimum home size, so ask City of Banks Planning Services before you count on any of them10.

What are the lot size and setback rules in the Banks RE zone?

In the Residential Estate (RE) zone, a single-family detached lot needs at least 10,000 square feet, subject to the city's lot-size-averaging provisions, and RE lots top out at 15,000 square feet11. Buildings may cover up to 50 percent of an RE lot12, and the height limit is 30 feet13.

RE setbacks are 15 feet in front, 5 feet on the side, 10 feet on a street side and 10 feet at the rear, with accessory structures allowed 2 feet from the rear line14. These figures are for RE only. Other Banks districts have their own tables, so read the standards for your parcel's zone.

Do you need a building permit in Banks, and who issues it?

Oregon requires permits for all new construction and for structural, plumbing, mechanical and electrical alterations to existing homes4. We could not confirm which office issues residential building permits inside Banks city limits, or its fees. Washington County Building Services handles building permits for unincorporated land, and its rules do not automatically apply inside the city15.

Call City of Banks Planning Services at 503-324-5112 before you buy to ask who reviews and inspects residential building permits for your address10. Land use approval is a separate step from a building permit, and the city's planning office handles land use applications10.

If your lot touches a mapped special flood hazard area, Banks requires a development permit before construction or fill begins16.

How do septic permits work in Banks?

Washington County Environmental Health issues septic system permits for households that are not served by public sewer2. Oregon county rules require a permit for installing a new onsite system and for repairing or altering an existing one17. After a permitted system is built, the installer or permittee must notify the county before the trench is covered, and the county has seven business days to inspect unless it waives inspection18.

We could not confirm whether a specific address inside Banks is on city sewer. Ask the city's public works staff at 503-324-5112, and call Environmental Health at 503-846-8722 if the lot would need its own system1019. Washington County's soils are a caution: only about 2 percent rate as not limited for a conventional drain field, so expect a site evaluation20.

Building a home in Banks: the steps, in order

  1. Call City of Banks Planning Services and confirm the zone, setbacks and whether a land use application is needed10.
  2. Ask the city whether the lot is on public sewer. If it is not, apply to Washington County Environmental Health for a septic permit2.
  3. Confirm with the city who issues the residential building permit for your address, then apply. Oregon requires permits for new construction4.
  4. If you are drilling your own well as the landowner, you need a state permit, a $10,000 bond or letter of credit and a $550 fee before work starts8.
  5. Before moving in, get the certificate of occupancy: Oregon requires one before occupancy of a new residential dwelling21.

What stays with Washington County, and what to check before you buy in Banks

Septic permits and the county's environmental health review stay with Washington County, not the city2. Land outside Banks city limits follows county rules instead. The county page for Washington County covers unincorporated land, where for example living in an RV is prohibited except for approved health hardship permits22. Do not assume that rule or any other county rule applies inside Banks.

Before you buy, check the flood hazard map for the parcel16. Also ask the city about its water supply status, because the city website lists past resolutions on a development moratorium due to a municipal water supply shortage23. Washington County's effective property tax rate is 0.9 percent24.

Watch-outs

  • We could not confirm who issues residential building permits inside Banks, or how Banks handles RVs, tiny homes, minimum home size, driveways and permit fees; call City of Banks Planning Services at 503-324-511210.
  • The City of Banks website lists resolutions renewing a moratorium on new development because of a documented municipal water shortage, and we could not confirm whether one is in force now; ask the city before you buy a lot23.
  • Washington County's own rules on RVs, tiny homes and lot sizes apply to unincorporated land only, not inside Banks9.

Sources

  1. Banks Municipal Code § 151.020, Zones (Banks), quoted and re-checked
  2. Onsite Sewage, quoted and re-checked
  3. Banks Municipal Code § 151.020, Zones (Banks), quoted and re-checked
  4. About Oregon residential building permits, quoted and re-checked
  5. Banks Municipal Code § 151.036, Permitted land uses in residential zones (Banks), quoted and re-checked
  6. Banks Municipal Code § 151.075, Accessory dwelling unit (Banks), quoted and re-checked
  7. 2023 Oregon Residential Specialty Code, Chapter 1, quoted and re-checked
  8. Landowner Constructed Wells, quoted and re-checked
  9. Urban & Rural Land Use Districts, quoted and re-checked
  10. City of Banks Planning Services (cityofbanks.org)
  11. Banks Municipal Code § 151.037, Development standards for residential zones (Banks), quoted and re-checked
  12. Banks Municipal Code § 151.037, Development standards for residential zones (Banks), quoted and re-checked
  13. Banks Municipal Code § 151.037, Development standards for residential zones (Banks), quoted and re-checked
  14. Banks Municipal Code § 151.037, Development standards for residential zones (Banks), quoted and re-checked
  15. Washington County’s Inspection Request Process, quoted and re-checked
  16. Banks Municipal Code § 151.367, Applicability (Banks), quoted and re-checked
  17. Onsite Sewage Permits, quoted and re-checked
  18. Final Inspection Request and Notice for Onsite Sewage Disposal System Permits, quoted and re-checked
  19. Washington County Environmental Health (Onsite Sewage Program) (washingtoncountyor.gov)
  20. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  21. 2023 Oregon Residential Specialty Code, Chapter 1, quoted and re-checked
  22. Can I live in my recreational vehicle (RV)?, quoted and re-checked
  23. City of Banks Public Works / Water (cityofbanks.org)
  24. Effective property tax rate: Bolthole Index county data

Written October 24, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Banks

Banks’s own rules

  • Local zoningPresent (with conditions)

    Land within the corporate limits of Banks city.

    • Uses are limited to those permitted in the zone in which the land is situated.
    “All lands, tracts, and area within the corporate limits of the City of Banks are hereby included within 1 of the following described land use zones. The uses of land within the corporate limits of the city shall be limited to those permitted in the zone within which lands are situated.”
  • Zoning districtsPublished (with conditions)

    Zoning districts for land within Banks city limits.

    • Residential use table identifies RE, LDR, MDR-L, MDR-H, HDR, and MU districts.
    “Land Use | RE | LDR | MDR-L | MDR-H | HDR | MU”
  • Manufactured homesAllowed (with conditions)

    Manufactured homes on individual lots in Banks RE, LDR, MDR-L, and MDR-H residential zones.

    • Table 2.2-A marks manufactured homes on individual lots as permitted in RE, LDR, MDR-L, and MDR-H, and not permitted in HDR and MU.
    • Permitted uses are subject to site/development review under the table key.
    “Manufactured Home - Individual Lot | P | P | P | P | N | N”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling units in Banks residential zones.

    • One ADU maximum per lot.
    • ADU floor area may not exceed 800 square feet or 75% of the primary dwelling floor area, whichever is smaller, except a conversion of a primary-dwelling level or floor may occupy that entire level or floor.
    • ADUs must meet underlying-zone building standards, subject to listed exceptions.

    maximum ADUs per lot: 1 · maximum ADU floor area: <= 800 square feet (or 75% of the primary dwelling's floor area, whichever is smaller; conversion exception stated in § 151.075(B)(2))

    “A maximum of 1 ADUs is allowed per lot. The ADU may be internal to the primary residence or a detached, separate unit.”
  • Building in a floodplainRequired

    Construction or development in areas of special flood hazard within Banks city limits.

    • A development permit must be obtained before construction or development begins.
    • Applies to all structures including manufactured homes and all development including fill and other activities.
    • The flood-damage-prevention subchapter applies to all special flood-hazard areas within the city.
    “A development permit shall be obtained before construction or development begins with any area of special flood hazard established in § 151.368. The permit shall be for all structures including manufactured homes, as set forth in the "Definitions" and for all development including fill and other activities, also set forth in the "Definitions."”
  • Permit processPartial

    Flood-hazard development permits inside Banks city limits.

    • Only applies in areas of special flood hazard established in § 151.368.
    • Application may include the listed plans and information.
    “Development permit required. A development permit shall be obtained before construction or development begins with any area of special flood hazard established in § 151.368.”

Rules another office applies inside Banks

Banks does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Minimum lot sizeSpecified

    Single-family detached dwellings in Banks Residential Estate (RE) zone.

    • Minimum lot sizes may vary under the lot-size-averaging provisions in § 152.005.
    • RE maximum lot size is 15,000 square feet.

    minimum lot area: >= 10000 square feet (Single-family detached dwelling in RE; subject to lot-size averaging.)

    “Minimum Lot Area (square feet)1 Single-Family Detached Duplex Triplex Fourplex Townhome Townhome Center Lot Cottage Cluster Multi-Family | 10,000 2 10,000 NA NA NA NA NA NA [...] Minimum lot sizes may vary from these standards per the lot size averaging provisions in § 152.005 2. Maximum lot size in RE Zone is 15,000 sf.”
  • SetbacksSpecified

    Single-family residential development in Banks Residential Estate (RE) zone.

    • Front setback may be reduced by up to 5 feet for an unenclosed front porch when the stated conditions are met.
    • There shall be no encroachment into public utility easements.

    minimum front yard: >= 15 feet (RE zone) · minimum side yard: >= 5 feet (RE zone) · minimum street side yard: >= 10 feet (RE zone) · minimum rear yard: >= 10 feet (All other structures; accessory structure is 2 feet)

    “Minimum Front Yard (feet)4 | 15 | 15 | 15 | 10 | 5 | 0 Minimum Side Yard (feet) Townhome (interior side yard) Accessory Structures 5 | 5 NA 2 | 5 NA 2 | 5 0 2 | 5 0 2 | 0 0 2 | 0 4 0 2 Minimum Street Side Yard (feet) | 10 | 10 | 10 | 10 | 5 | 5 Minimum Rear Yard (feet) Accessory Structure All Other | 2 10 | 2 10 | 2 10 | 2 10 | 2 10 | 2 10”
  • Lot coverageSpecified

    Single-family detached dwellings in Banks Residential Estate (RE) zone.

    maximum building coverage: <= 50 percent (Single-family detached dwelling in RE zone)

    “Maximum Building Coverage (%) Single-Family Detached Duplex Triplex Fourplex Townhome Cottage Cluster Multi-Family | 50 NA NA NA NA NA NA”
  • Building heightSpecified

    Buildings in Banks Residential Estate (RE) zone.

    • Accessory structures within 5 feet of a side yard must be less than 15 feet high.
    • Cottage-cluster buildings in all zones have the separately stated maximum.

    maximum building height: <= 30 feet (RE zone)

    “Maximum Building Height (feet)6 | 30 | 30 | 35 | 35 | 40 | 35 or 45 7”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Banks or Washington County directly.

  • Building permit — Residential building construction inside Banks city limits.
  • Owner-builder exemption — Owner-built residential construction inside Banks city limits.
  • Building code adopted — Building-code adoption for construction inside Banks city limits.
  • Inspections — Residential building inspections inside Banks city limits.
  • Certificate of occupancy — New residential occupancy inside Banks city limits.
15 more unanswered
  • Minimum dwelling size
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Short-term rentals
  • Permit fees

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Banks publishes no rule on the point, not that none exists. Washington County’s page lists the county offices to call.

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