Zoning, building permits and septic rules in Centralia, Washington

Centralia’s own rules

• Building permitRequired

  Almost all construction projects inside Centralia city limits, including new residential structures.

  • The City lists minor replacements as possible electrical exemptions.
  • parameters are project-specific.

  “Almost all construction projects in the City need a building permit includes the following:”

• Building code adoptedAdopted (with conditions)

  Building work inside Centralia city limits.

  • City page identifies Title 18 as Building Regulations.

  adopted code edition: 2021

  “Building Regulations (Title 18): Building requirements (The City has adopted the 2021 codes) and Sign codes.”

• InspectionsRequired

  Residential permitted construction inside Centralia city limits.

  • Final approval is also required from State L&I, Fire, and City Engineering when applicable.
  • The checklist asks applicants to allow at least three working days for final inspections.

  “Final Inspection: before calling for your final building inspection you must have final inspection and approval from the following agencies:”

• Local zoningPresent (with conditions)

  Land inside Centralia city limits.

  • Title 20 zoning controls remain parcel- and district-specific.

  “The Centralia Municipal Code can be found online with the Zoning Ordinance as Title 20.”

• Accessory dwellingsAllowed (with conditions)

  A single lot in permitted zoning districts inside Centralia city limits.

  • Up to two ADUs may be created.
  • Physical conditions, critical areas, and on-site sewage infrastructure may prohibit an ADU.
  • Building and other applicable permits are required before construction.
  • Utility, parking, setback, and applicable-code rules apply.

  maximum accessory dwelling units: <= 2 units per lot (Only in permitted zoning districts)

  “Up to two accessory dwelling units may be created on a single lot in permitted zoning districts.”

• Mandatory utility hookupConditional

  Accessory dwelling units inside Centralia city limits.

  • R:4, R:8, R:15, and R:20 ADUs must connect to all City utilities.
  • R-5A and R:2 ADUs must connect to City water and electric.
  • ADUs not required to connect to City sewer must meet Lewis County septic-system requirements.

  “In the R:4, R:8, R:15, and R:20 zoning districts, accessory dwelling units shall connect to all city utilities. In the R5:A and R:2 zoning districts, accessory dwelling units shall connect to city water and electric.”

• Subdividing landRegulated (with conditions)

  Creation of residential lots inside Centralia city limits.

  • A detached single-family dwelling or other residential building must be on its own lot except for a secondary dwelling.
  • Lot creation must meet subdivision and short-plat code requirements.

  “Creation of a lot or lots shall meet all requirements of the subdivision and short plat code.”

• Building in a floodplainRequired

  Structures in areas subject to Centralia floodplain-management requirements.

  • Applies to all structures under the residential chapter; exact floodplain applicability is governed by CMC Chapter 16.21.

  “All structures shall comply with the floodplain management requirements of Chapter 16.21 CMC.”

• Permit feesPublished (with conditions)

  Building and land-use permits inside Centralia city limits.

  • The cited 2026 fee schedule has land-use fees in Section 4 and building fees in Section 5.
  • The City says a 3.5 percent fee applies to debit/credit-card permit payments.

  “The City Council adopted the Building Permits Fees and Land Use Fees for 2026, and they went into effect on January 1, 2026.”

• Permit processPublished (with conditions)

  Residential building permits inside Centralia city limits.

  • Application and checklist must be completed.
  • Planning and Engineering approvals and fees are collected.
  • Plan review may generate corrections before permit issuance.

  “The permit application and plans are then reviewed by our Building Division to make sure all of the information is accurate and meets specific code requirements.”

Rules another office applies inside Centralia

Centralia 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-5A rural residential district inside Centralia city limits.

  • Table also sets density at zero to one unit per five acres, minimum lot width at 100 feet, and maximum coverage at 10 percent.

  minimum lot area: 217800 square feet

  “R-5A | 0 – 1 unit per 5 acres | 217,800 | 100 | 10”

• SetbacksSpecified

  R-5A rural residential district inside Centralia city limits.

  • Street-side setback is 20 feet where the garage vehicle entrance is on that side.

  front/rear/non-street-side/street-side setback: 20/25/10/15 feet (Street-side is 20 feet if the vehicle entrance of the garage)

  “R-5A | 20 | 25 | 10 | 15 or 20 if the vehicle entrance of the garage”

• Lot coverageSpecified

  R-5A rural residential district inside Centralia city limits.

  • The table also establishes density, lot-area, and width requirements.

  maximum lot coverage: <= 10 percent

  “R-5A | 0 – 1 unit per 5 acres | 217,800 | 100 | 10”

Still unanswered

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

• Owner-builder exemption — Owner-built residential work inside Centralia city limits.
• Certificate of occupancy — New residential construction inside Centralia city limits.
• Minimum dwelling size — Dwellings inside Centralia city limits.
• Living in an RV — RV occupancy as a principal or temporary residence on private land inside Centralia city limits.
• Camping on your land — Temporary camping on private land inside Centralia city limits.

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.

Off-grid gear

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

• Water Crystal Quest Filter any source — well, rain, or creek — to drinking-clean.
• Power Bluetti Solar generators and home battery backup for living off the grid.
• Septic Soil percolation test kit Run your own perc test before paying an engineer — the first thing a septic office asks about.
• Water Well water test kit Bacteria, nitrates, hardness — know what the well on a parcel is really pumping.

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