Bolthole Index

Washington County, Oregon

Zoning, building permits and septic rules in Forest Grove, Oregon

Forest Grove, Oregon, a city in Washington County, adopts and enforces its own Development Code and zoning inside city limits1. New homes go through the city's Building Division, not the county2. Sewer connection is required in some cases, and septic permits for households off public sewer come from Washington County Environmental Health34.

At a glance

Zoning
City of Forest Grove Development Code applies inside city limits15
Building permits
Applications for new homes go to the city Building Division by email or the state ePermitting site2
Septic
County Environmental Health permits septic for households off public sewer; city sewer connection can be required43
Accessory dwellings
Allowed with a single-family home, one per detached dwelling6
Manufactured homes
Allowed on individual lots except in national historic districts7
R-5 minimum lot
3,500 square feet for a single-family detached home on a new division8
Residential setbacks
Front 14 feet to dwelling, 20 feet to garage; side 5 feet; rear 15 feet9
RV and tiny-home living
Not confirmed inside city limits; ask Planning6

Who to call

Building permits

City of Forest Grove Building Division

Building permits, permit exemptions and inspections inside Forest Grove city limits

503-992-3229

1924 Council Street, Forest Grove, OR 97116

Building permits

City of Forest Grove permitting process (Building and Planning)

Step-by-step permitting for new homes, duplexes and additions inside Forest Grove

Planning & zoning

City of Forest Grove Planning Division

Zoning information, land-use applications and the Development Code inside Forest Grove city limits

503-992-3200

1924 Council Street, Forest Grove, OR 97116

Septic permits

Washington County Environmental Health (Onsite Sewage Program)

Septic system permits for households not served by public sewer

503-846-8722

[email protected]

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 Forest Grove means bringing your own water and power. The kit we’d start with:

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Does Forest Grove, Oregon have zoning, and what does it mean for lots and setbacks?

Yes. Forest Grove enacted its Development Code, Title XVII, as the city's own land-use law, and it applies to land inside Forest Grove city limits1. The code publishes zoning districts, and rules differ by district5. To look up a parcel, the Planning Division points to its online zoning map10.

In the R-5 residential zone, a single-family detached home on a new land division needs at least 3,500 square feet8. A single-unit detached dwelling in the residential zones must sit at least 14 feet back from the front line, with garages and parking 20 feet back, 5 feet from an interior side line and 15 feet from the rear line9. Height is capped at 35 feet in the SR, R-7, R-5 and RM zones, and accessory buildings at 25 feet11.

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

New single-family homes, duplexes and additions in Forest Grove start with a building permit application submitted to the city by email or through the state's ePermitting site2. Contractors can pull permits online through the state's e-permitting website12. The city's Building Division handles this work, not Washington County Building Services, whose office serves unincorporated land only.

We could not confirm the city's full list of permit-exempt work, its adopted building-code section or its owner-builder procedure in the city's code; call the Building Division at 503-992-3229 before you start12. Oregon applies the 2023 Oregon Residential Specialty Code to one- and two-family dwellings statewide13.

How do septic permits work inside Forest Grove?

Forest Grove requires every residence and building to have a sanitary method of sewage disposal where city sanitary sewer is not available14. Where the county or state Department of Environmental Quality finds an existing onsite system has failed or needs repair and the city sewer line is physically available, the property must connect3. After written notice, continued use of an outside toilet, cesspool or septic tank for 30 days can lead to a water shutoff3.

Washington County Environmental Health issues septic system permits for households not served by public sewer15. Whether it administers septic permits for parcels inside Forest Grove's city limits is not stated in the city code, so call the same office to confirm before relying on a septic plan15. Countywide, only about 2% of soils rate as not limited for a conventional drain field, so a site evaluation or an engineered system is the likely path16.

Can you build an accessory dwelling or place a manufactured home in Forest Grove?

Accessory dwelling units, including manufactured homes used as ADUs, are allowed with a single-family dwelling in any Forest Grove residential zone, with a maximum of one per detached dwelling, and must meet the code's Article 7 standards6. Oregon law also requires larger cities to allow at least one accessory dwelling per detached single-unit dwelling17. Detached accessory buildings of one story must sit at least five feet from side and rear property lines9.

Manufactured homes on individual lots are allowed in Forest Grove except within national historic districts, subject to Article 7 standards7. Manufactured-home parks are conditional uses in several residential zones7.

Can you live in an RV or tiny home in Forest Grove?

We could not confirm Forest Grove's rules for living in an RV on a private lot, temporary camping or tiny homes; the Development Code provisions we reviewed cover RV parks but not private-lot RV occupancy6. Ask the Planning Division at 503-992-3200 before parking or occupying either on a city lot10.

Washington County's rules for unincorporated land do not carry into the city. The county's ban on living in an RV as a dwelling applies only outside city limits18. A tiny home built on a permanent foundation can qualify as an accessory dwelling where the code allows ADUs6.

Building a home in Forest Grove: the steps, in order

  1. Check the parcel's zone and standards with the Planning Division using the city's zoning map10.
  2. Obtain a Clean Water Services provider letter2.
  3. Submit the building permit application by email or through the state ePermitting site; Planning, Engineering, Building and Light and Power review the plans2.
  4. Pay permit and development fees, which include sanitary sewer, water service, building, traffic impact, plumbing and mechanical charges2. The city's sewer connection fee is fixed by Council resolution19.
  5. Build and schedule required inspections through the Building Division12.
  6. Before move-in, call for a final inspection and obtain a Certificate of Occupancy2.

City offices are open 8 AM to 5 PM Monday through Thursday and 8 AM to 4 PM Friday2.

What stays with Washington County, and what to check before you buy in Forest Grove?

Septic permits for households off public sewer come from Washington County Environmental Health15. Landowners who dig their own water-supply well need a state permit, a bond or irrevocable letter of credit of $10,000 and a $550 permit fee before work begins20. A new driveway or approach onto a state highway needs written ODOT permission21. Land outside city limits follows the county's rules; see the Washington County page.

Washington County's effective property tax rate is 0.9%, and the median property tax bill is $4,852 per year2223. The typical home value is about $569,00024.

Watch-outs

  • We could not confirm Forest Grove's rules for floodplain development, short-term rentals, driveway access from city streets or private wells inside city limits; call the Planning Division at 503-992-320010.
  • Oregon's owner-builder exemption only relaxes structural-code rules for ceiling heights, room sizes and temperature maintenance and does not remove permit, inspection or land-use requirements25.
  • A failed septic system can trigger a mandatory city sewer connection when the sewer line is physically available3.

Sources

  1. Title XVII: Development Code (Forest Grove), quoted and re-checked
  2. City of Forest Grove permitting process (Building and Planning) (forestgrove-or.gov)
  3. § 52.03 Connection Required (Forest Grove), quoted and re-checked
  4. Onsite Sewage, quoted and re-checked
  5. Article 3: Zoning Districts (Forest Grove), quoted and re-checked
  6. codelibrary.amlegal.com (Forest Grove), quoted and re-checked
  7. § 17.3.120 Use Regulations (Forest Grove), quoted and re-checked
  8. § 17.3.130 Residential Development Standards (Forest Grove), quoted and re-checked
  9. § 17.3.130 Residential Development Standards (Forest Grove), quoted and re-checked
  10. City of Forest Grove Planning Division (forestgrove-or.gov)
  11. § 17.3.130 Residential Development Standards (Forest Grove), quoted and re-checked
  12. City of Forest Grove Building Division (forestgrove-or.gov)
  13. Residential Structures Code Program (Oregon statewide rule), quoted and re-checked
  14. § 52.03 Connection Required (Forest Grove), quoted and re-checked
  15. Washington County Environmental Health (Onsite Sewage Program) (washingtoncountyor.gov)
  16. 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
  17. Oregon Revised Statutes, ORS 197A.425 (Oregon statewide rule), quoted and re-checked
  18. Can I live in my recreational vehicle (RV)?, quoted and re-checked
  19. § 52.06 Application for Sewer Permit (Forest Grove), quoted and re-checked
  20. Landowner Constructed Wells (Oregon statewide rule), quoted and re-checked
  21. Access Management (Oregon statewide rule), quoted and re-checked
  22. Effective property tax rate: Bolthole Index county data
  23. Median property tax bill: Bolthole Index county data
  24. Typical home value (Zillow): Bolthole Index county data
  25. Oregon Revised Statutes, ORS 455.320 (Oregon statewide rule), quoted and re-checked

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 Forest Grove

Forest Grove’s own rules

  • Local zoningPresent (with conditions)

    Land inside Forest Grove city limits.

    • Title XVII was enacted by Ordinance 2019-04, effective May 28, 2019, and later amendments shown in the hosted code may apply.
    “Ord. 2019-04, effective May 28, 2019, enacted this Title XVII and repealed Ord. 2009-01, which enacted the Development Code of 2009.”
  • Zoning districtsPublished (with conditions)

    Zoning districts inside Forest Grove city limits.

    • District-specific use, dimensional, and development standards apply.
    “Zoning Map § 17.3.010 Classification of zones Table 3-1 Zoning Districts § 17.3.020 Official zoning map”
  • Manufactured homesLimited

    Manufactured homes on individual lots in Forest Grove residential zones.

    • Manufactured homes on individual lots are prohibited within national historic districts.
    • They must comply with Article 7 standards.
    • Manufactured-home parks are conditional uses in R-7, R-5, RM, and RH zones and not permitted in SR.
    “Manufactured homes on individual lots are permitted except within national historic districts, subject to compliance with the standards in Article 7. Manufactured homes are prohibited within a national historic district.”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling units associated with a single-family dwelling in any Forest Grove residential zone.

    • Must comply with Article 7 accessory-dwelling-unit standards.
    • Manufactured-home ADUs are prohibited in historic districts.
    • Maximum one ADU per single-unit detached dwelling.

    maximum ADUs per single-unit detached dwelling: <= 1 ADU

    “Accessory dwelling units - including manufactured homes - are allowed in conjunction with a single-family dwelling in any residential zone, subject to compliance with the accessory dwelling unit standards in Article 7. Manufactured home ADUs are prohibited in historic districts.”
  • Off-grid sanitationLimited

    Residences and buildings inside Forest Grove city limits where city sanitary sewer is unavailable.

    • A sanitary sewage-disposal method is required where city sanitary sewer is unavailable.
    • If the onsite system fails or needs repair and a city sewer connection is physically available, connection is required.
    “In areas where city sanitary sewers are not available for connection, every residence, building, or place where human beings reside, assemble, or are employed within the city shall be required to have a sanitary method for disposal of sewage.”
  • Mandatory utility hookupSewer (with conditions)

    Every residence, building, or place where people reside, assemble, or are employed inside Forest Grove city limits.

    • Connection is required only when the County or State Department of Environmental Quality determines the existing onsite system has failed or needs repair and the city sewer line is physically available under O.A.R. 340-071-0160.
    • Where city sewers are unavailable, a sanitary sewage-disposal method is required.
    • After written notice, continued construction, maintenance, or use of an outside toilet, cesspool, or septic tank for 30 days can result in water shutoff.

    notice period before water-service remedy: 30 days (After service of written notice to connect with the public sewer.)

    “Every residence, building, or place where human beings reside, assemble, or are employed within the city shall be required to connect to the city sanitary sewer system where the following conditions exist:”
  • Subdividing landRegulated (with conditions)

    Subdivisions and other land divisions inside Forest Grove city limits.

    • The code contains tentative-plat application and review requirements, final-plat review criteria, improvement requirements, and final-plat time limits, approval, and recording provisions.
    “Subdivisions § 17.6.095 Purpose § 17.6.100 Procedure § 17.6.105 Application requirements for tentative plat review § 17.6.110 Tentative plat review criteria”
  • Permit feesVariable (with conditions)

    City sewer-connection permits inside Forest Grove city limits.

    • The city connection fee is fixed by Council resolution.
    • This sewer-connection fee is not subject to annual fee adjustment.
    “The fee charged by the city to connect the sewer shall be fixed by Council resolution. Fees in this section are not subject to the annual fee adjustment.”
  • Permit processPartial

    City sewer-connection permits inside Forest Grove city limits.

    • A licensed sewer contractor employed to do the work files the application.
    • The application must identify the owner or occupant, buildings and occupancy purpose, and include plans and specifications.
    • The City Engineer may modify the plans and specifies connection manner, location, material, and size before issuing the permit.
    “A licensed sewer contractor employed to do the work shall file an application. The application shall include: (1) The name of the owner or occupant of the premises to be connected; (2) The number of buildings and the purposes for which they are or are to be occupied;”

Rules another office applies inside Forest Grove

Forest Grove 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

    R-5 residential zone inside Forest Grove city limits; single-family detached homes and manufactured homes on new land divisions.

    • The table's minimum and maximum lot sizes apply to land divisions.
    • Larger parcels than the table's maximum are allowed for phased development, open space, or undevelopable tracts.

    minimum lot size: >= 3500 square feet (Single-family detached or manufactured home in R-5.)

    “Single-family detached | 3,500 square feet | 15,000 square feet | Depth: 60 feet | Width: 34 feet”
  • SetbacksSpecified

    Single-unit detached dwellings in Forest Grove residential zones.

    • Accessory buildings, including accessory dwellings and detached garages, not exceeding one story must be at least five feet from side and rear property lines.
    • Other housing types and multifamily structures have distinct setbacks and buffering rules.

    front-yard setback to dwelling: >= 14 feet (Single-unit detached dwelling.) · front-yard setback to garage or parking area: >= 20 feet (Single-unit detached dwelling.) · interior side-yard setback: >= 5 feet (Single-unit detached dwelling.) · rear-yard setback: >= 15 feet (Single-unit detached dwelling.)

    “Single-unit detached | 14 feet | 20 feet | 5 feet | 15 feet”
  • Building heightSpecified

    Buildings in Forest Grove SR, R-7, R-5, and RM residential zones.

    • Accessory buildings are limited to one and one-half stories or 25 feet, whichever is less.
    • A chimney, radio or television antenna, or solar/wind energy device may exceed the limit by up to 15 feet.
    • Church steeples may exceed 35 feet through a Type II process.

    maximum building height: <= 35 feet (SR, R-7, R-5, and RM zones; also limited to two and one-half stories, whichever is less.)

    “Buildings in the SR, R-7, R-5 and RM Zones are limited to a maximum height of two and one-half stories or 35 feet, whichever is less. Accessory buildings are limited to a maximum height of one and one-half stories or 25 feet, whichever is less.”

Still unanswered

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

  • Building permit — Residential building construction inside Forest Grove city limits.
  • Owner-builder exemption — Owner-built residential construction inside Forest Grove city limits.
  • Building code adopted — Building construction inside Forest Grove city limits.
  • Inspections — Building construction inside Forest Grove city limits.
  • Certificate of occupancy — New or altered buildings inside Forest Grove city limits.
12 more unanswered
  • Minimum dwelling size
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Well permit
  • Agricultural exemption
  • Driveway access
  • Building in a floodplain
  • Short-term rentals

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 Forest Grove publishes no rule on the point, not that none exists. Washington County’s page lists the county offices to call.

← All of Washington County: county rules, score and offices