Mason County Building Permit Guide (Unincorporated Area)

Permit Authority

All properties in unincorporated Mason County.

Department

Mason County Community Development Department, Building Division

Address

615 W Alder Street, Building 8, Shelton, WA 98584

Phone

(360) 427-9670, Extension 352

Email

Contact via website contact form

Website

https://www.masoncountywa.gov/departments/community_development/building/

Online Permit Portal

Application Process

1. Gather information: tax parcel number, site information, building plans, and any prior property approvals.
2. Schedule a planning pre-site inspection to determine if site contains critical areas (slopes, creeks, wetlands, shorelines).
3. Obtain address assignment from Permit Center Addressing Section (ext. 284) for 911 purposes.
4. Obtain road access permit from Mason County Public Works (ext. 450) if property accesses county or state maintained roads.
5. Arrange septic permit if applicable: contact Washington State certified septic designer and Environmental Health (ext. 400).
6. Complete water adequacy application with well report/log and water sample within 12 months for well-served properties.
7. Submit complete application package in person (appointment required) to Permit Center at 615 W Alder Street.
8. Submit 50% of building permit fee plus planning site review fee at time of application.
9. County conducts simultaneous review by Planning, Building, and Environmental Health departments.
10. Respond to any correction comments and resubmit revised documents if required.
11. Pay remaining permit fees and obtain permit issuance before starting work.

Typical processing time: Varies based on project complexity and review comments. Budget 3-6 weeks for standard residential permits.

Source: Mason County Community Development Department, Building Division

General Requirements

A building permit is required for most construction activities in unincorporated Mason County. Owner-builders may apply, but all contractors must be registered with Washington State L&I.

Required Documents

• Road access permit approval (if on county or state maintained road)
• Site address assignment confirmation
• Building permit application
• Plumbing/Mechanical permit application
• Site plan (one copy, drawn to scale)
• Water Adequacy Application (for well-served properties)
• Building construction drawings (three sets, drawn to scale, minimum 1/4 inch)
• Engineering calculations (two sets, if required)
• Washington State Energy Code Form
• Geotechnical Reports (three sets, if required)
• Small parcel drainage plan/Stormwater worksheet
• Wetland Delineation (one set, if required)
• Environmental Health Development Application
• Septic system approval (if applicable)

Permit validity

Permit valid for 180 days from last inspection. Must have at least one inspection every 180 days to keep permit active.

Building code

2021 International Building Code (IBC), 2021 International Residential Code (IRC), 2021 International Mechanical Code (IMC), 2021 Uniform Plumbing Code (UPC), 2021 International Fire Code (IFC), 2021 Washington State Energy Code (WSEC), all as amended by WAC and local ordinance. National Electrical Code (NEC) enforced by L&I.

Owner-builder

Owner-builders may apply but must comply with all code and contractor registration requirements.

Contractor requirements

All contractors must be registered with Washington State Department of Labor & Industries (L&I). L&I registration number required on application.

Fees

Minimum permit fee

$156.00

Plan check fee

65% of building permit fee (collected at submittal)

Permit fee formula

Based on ICC Building Valuation Data: $1-$500 = $25.00; $501-$2,000 = $25.00 + $3.00 per each additional $100; $2,001-$25,000 = $70.00 + $14.00 per additional $1,000; $25,001-$50,000 = $390.00 + $10.00 per additional $1,000; $50,001-$100,000 = $640.00 + $7.00 per additional $1,000; $100,001-$500,000 = $1,000.00 + $6.00 per additional $1,000; $500,001-$1,000,000 = $3,400.00 + $5.00 per additional $1,000; $1,000,001+ = $5,700.00 + $7.00 per additional $1,000

Trade permit fee

Varies by trade; see current fee schedule

Reinspection fee

Charged when applicable; see current fee schedule

Penalty (no permit)

Penalties apply for construction without permit; consult county office

Payment note

Payment methods: cash, check, money order payable to Mason County Treasurer. Technology fee and State Building Fee per RCW 19.27.085 apply.

Fees change. Verify current amounts at the official fee schedule (effective Updated annually in September).

Work That Does NOT Require a Permit

• One-story detached accessory structures (tool/storage sheds, playhouses) not exceeding 200 square feet with no utilities
• Fences not over 7 feet high
• Retaining walls not over 4 feet in height (measured from bottom of footing to top of wall) unless supporting surcharge
• Water tanks supported directly on grade with capacity not exceeding 5,000 gallons
• Sidewalks, driveways, and on-grade patios not more than 30 inches above grade
• Painting, papering, tiling, carpeting, cabinets, countertops, and similar finish work
• Prefabricated swimming pools less than 24 inches deep
• Swings and playground equipment accessory to one- or two-family dwellings
• Window awnings not projecting more than 54 inches from exterior wall
• Shipping containers used for residential storage with no utilities (verify with Building Department)

Important: Exemptions from building permit do not authorize work done in violation of code. Separate plumbing, electrical, and mechanical permits may still be required. All work must comply with zoning and critical areas requirements. Confirm edge cases with the Building Division before proceeding.

Inspections

How to Schedule

• (360) 427-9670, Extension 352 (phone)
• SmartGov Portal (online)
• Building Department at 615 W Alder Street (in-person)

Scheduling deadline

Requests received prior to 3:00 PM confirmed same business day; requests after 3:00 PM processed next business day.

Inspection hours

Monday-Friday, 9:00 AM to 4:00 PM

Time windows

No specific time windows; inspections normally occur between 9:00 AM and 4:00 PM.

Typical inspection sequence: Typical sequence: Footing and Setback, Foundation Wall, Concrete Slab, Electrical (L&I), Framing/Plumbing/Mechanical Rough, Interior Gas Piping/LPG Tank, Insulation, Gypsum Board, Final Electrical (L&I), Final Inspection. County divided into inspection areas inspected on different days of the week; call office for area schedule.

Remote inspections not specified; verify with building department on a case-by-case basis.

Additional Resources

• Building code: 2021 International Building Code (IBC), 2021 International Residential Code (IRC), 2021 International Mechanical Code (IMC), 2021 Uniform Plumbing Code (UPC), 2021 International Fire Code (IFC), 2021 Washington State Energy Code (WSEC), all as amended by WAC and local ordinance. National Electrical Code (NEC) enforced by L&I.
• Verify contractor license: WA L&I Contractor Lookup
• Zoning information: View zoning info
• Owner-builder rules: View rules
• Current Building Codes and Standards
• Planning Pre-Site Inspection Form
• Address Request Form
• Water Adequacy Application
• License lookup guide: Washington Contractor License Requirements
• Contract template: Washington Homeowner-Contractor Agreement
• Washington hub: Washington Contractor License & Permit Hub