Building permits, zoning and septic rules in Millwood, Washington

At a glance

Building permits

Required; building permitting and inspections through Spokane Valley¹⁵

Zoning

Millwood zoning applies inside city limits²

Site-plan review

Required reviews need Millwood approval before building permit approval³

Septic permits

Spokane Regional Health District handles new systems and changes to existing systems⁶

Tiny homes

State-code compliance and local approval required; Millwood siting eligibility needs confirmation⁷

Owner-built homes

Conditional contractor-registration exemption; building approval still applies⁸¹

Who to call

Contact details are copied from each office’s official page and were checked against it on October 11, 2026.

Do you need a building permit in Millwood, WA?

Millwood requires a written city permit before erecting a building or structure, making an alteration that changes use or occupancy, or instituting or changing a property use.¹ Millwood’s zoning provision exempts one-story detached tool and storage sheds, playhouses and similar accessory buildings with floor area no greater than 120 square feet; ask the City Planner how that exemption fits your proposed project.¹³ Washington’s State Building Code still applies inside Millwood, so a permit exemption does not establish freedom from construction standards.⁹ Millwood’s city council sets fees by resolution for building, change-of-use, demolition, fence, manufactured-home, mechanical and plumbing permits; request the current charges for your project rather than budgeting from a county fee schedule.¹⁰

Who handles Millwood building permits and inspections?

Millwood partners with the City of Spokane Valley for building permitting and inspections; contact the Spokane Valley Permit Center at (509) 720-5240.⁵ The inspection request line is (509) 720-5350.⁵ Required site-plan review must receive Millwood approval before building permit approval, and site-plan review fees may be payable to Millwood.³ Start zoning and site-plan questions with Millwood’s City Planner at [email protected], or call City Hall at (509) 924-0960.³ Commercial building permits are coordinated by the City Planner, including civil-plan and drainage review through the City Engineer.³

Does Millwood have zoning, lot-size rules and setbacks?

Millwood has its own zoning regulations for land inside city limits.² Millwood’s supplementary-use regulations make permitted uses conditional on the applicable district’s use table; an available parcel is not automatically eligible for the use you have in mind.¹¹ Before buying, ask the Millwood City Planner to confirm the parcel’s district, allowed residential use, minimum lot area, setbacks, height and lot coverage for your proposed building.³ We could not confirm a general Millwood minimum lot size or setback schedule, so obtain the parcel-specific standards from the City Planner before drawing a site plan.³ For land outside city limits, use the Spokane County guide: county zoning governs unincorporated Spokane County.¹²

How do septic permits work inside Millwood?

Spokane Regional Health District issues septic permits for new on-site sewage systems and changes to existing systems serving homes and other qualifying buildings with flows below 3,500 gallons per day.⁶ Millwood building approval and septic approval are separate: send sewage-system questions to the district’s Liquid Waste Program at 509.324.1560 ext. 1.³¹³ Washington requires an on-site sewage permit before covered installation, repair, modification, connection or expansion work begins, with an exception for minor repairs.¹⁴ SRHD reviews designs and inspects systems after installation; inspection and maintenance are required before renewable permit renewal.¹⁵ Ask Millwood about available sewer service before planning a septic system; City Hall retains utility permits.³

Can you live in an RV or tiny home in Millwood?

We could not confirm permission for long-term RV occupancy on private land in Millwood; ask the City Planner about the proposed address and use before relying on an RV as housing during construction.³ Millwood’s prohibition on camping in city-owned or city-maintained areas does not establish a private-land RV rule.¹⁶ Washington recognizes tiny houses, including qualifying houses on wheels, but requires State Building Code compliance and local approval for foundation, installation and location.⁷ A wheeled structure may instead be classified as an RV or park model, so have the building office establish the classification and ask Millwood to confirm the residential use before purchase.⁷⁵³

What are the steps to building a home in Millwood?

1. Ask Millwood’s City Planner to confirm the intended use and whether site-plan review is required; obtain required Millwood site-plan approval before building permit approval.²³
2. Confirm water and sewer arrangements with Millwood City Hall; if an on-site sewage system is proposed, obtain the applicable SRHD septic approval before sewage-system construction.³¹⁴⁶
3. Arrange building permitting and inspections through the Spokane Valley Permit Center, Millwood’s building-services partner.⁵
4. Ask Millwood which utility, grading, driveway approach or right-of-way permits the project also needs; those permit types remain with City Hall.³
5. If building your own home, confirm the Washington contractor-registration exemption applies to your circumstances; the exemption does not remove building or other approval requirements.⁸

What else should you check before buying land in Millwood?

Ask Millwood City Hall about water and sewer service and the approvals needed for a new connection; utility permits remain with the city.³ If considering a well, Washington’s domestic groundwater exemption covers up to 5,000 gallons per day per project, with withdrawals from multiple wells aggregated; local requirements and other water-law restrictions can still apply.¹⁷ Ecology must receive a notice of intent 72 hours before drilling, and that notice does not approve water use.¹⁷ For development in a floodplain, Washington directs applicants to the local government for floodplain development approval; ask Millwood to identify the applicable review before committing to a building site.¹⁸

Watch-outs

• Millwood’s written zoning permit expires after 1 year unless the authorized structure is completed or the authorized use is instituted; ask Millwood how that deadline applies alongside the building permit.¹⁹
• A Millwood small-accessory-building exemption does not establish approval to occupy the structure as a tiny home.¹⁷
• Confirm private-land RV occupancy with the Millwood City Planner before using an RV as temporary housing.³

Sources

1. Millwood Municipal Code § 17.44.040—Permit required for erection or alteration (Millwood), quoted and re-checked
2. Millwood Municipal Code Title 17, Appendix A—Definitions (Millwood), quoted and re-checked
3. City of Millwood — City Planner / City Hall (millwoodwa.us)
4. Septic Systems, quoted and re-checked
5. Spokane Valley Permit Center — building services for Millwood (millwoodwa.us)
6. New Systems or Changes to Existing Systems, quoted and re-checked
7. Tiny Houses (Washington statewide rule), quoted and re-checked
8. RCW 18.27.090 — Exemptions (Washington statewide rule), quoted and re-checked
9. RCW 19.27.031 — State building code—Adoption—Conflicts—Opinions (Washington statewide rule), quoted and re-checked
10. Millwood Municipal Code § 17.44.040—Permit required for erection or alteration (Millwood), quoted and re-checked
11. Millwood Municipal Code § 17.16.010—Supplementary use regulations (Millwood), quoted and re-checked
12. County Code, quoted and re-checked
13. Spokane Regional Health District — Liquid Waste Program (srhd.org)
14. WAC 246-272A-0200 Permit requirements (Washington statewide rule), quoted and re-checked
15. New Systems or Changes to Existing Systems, quoted and re-checked
16. Millwood Municipal Code § 12.12.030—Unlawful camping (Millwood), quoted and re-checked
17. Groundwater permit exemption (Washington statewide rule), quoted and re-checked
18. Planning & regulation — Washington State Department of Ecology (Washington statewide rule), quoted and re-checked
19. Millwood Municipal Code § 17.44.040—Permit required for erection or alteration (Millwood), quoted and re-checked

Written October 11, 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.