On this page 6
§ 02
When a permit is required
Permit triggers and exempt work for Mason County
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.
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)
- Exempt One-story detached accessory structures (tool/storage sheds, playhouses) not exceeding 200 square feet with no utilities
- Exempt Fences not over 7 feet high
- Exempt Retaining walls not over 4 feet in height (measured from bottom of footing to top of wall) unless supporting surcharge
- Exempt Water tanks supported directly on grade with capacity not exceeding 5,000 gallons
- Exempt Sidewalks, driveways, and on-grade patios not more than 30 inches above grade
- Exempt Painting, papering, tiling, carpeting, cabinets, countertops, and similar finish work
- Exempt Prefabricated swimming pools less than 24 inches deep
- Exempt Swings and playground equipment accessory to one- or two-family dwellings
- Exempt Window awnings not projecting more than 54 inches from exterior wall
- Exempt Shipping containers used for residential storage with no utilities (verify with Building Department)
Note: 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.
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)
- 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.
- Permit validity
- Permit valid for 180 days from last inspection. Must have at least one inspection every 180 days to keep permit active.
- 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.
Source: Mason County Community Development Department, Building Division ↗
§ 03
Application process
Typical processing: Varies based on project complexity and review comments. Budget 3-6 weeks for standard residential permits.
- 01 Gather information: tax parcel number, site information, building plans, and any prior property approvals.
- 02 Schedule a planning pre-site inspection to determine if site contains critical areas (slopes, creeks, wetlands, shorelines).
- 03 Obtain address assignment from Permit Center Addressing Section (ext. 284) for 911 purposes.
- 04 Obtain road access permit from Mason County Public Works (ext. 450) if property accesses county or state maintained roads.
- 05 Arrange septic permit if applicable: contact Washington State certified septic designer and Environmental Health (ext. 400).
- 06 Complete water adequacy application with well report/log and water sample within 12 months for well-served properties.
- 07 Submit complete application package in person (appointment required) to Permit Center at 615 W Alder Street.
- 08 Submit 50% of building permit fee plus planning site review fee at time of application.
- 09 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 ↗
§ 04
Fee schedule
Effective Updated annually in September
Fee type
Amount
01
Minimum permit fee
$156.00
02
Plan check fee
65% of building permit fee (collected at submittal)
03
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
04
Trade permit fee
Varies by trade; see current fee schedule
05
Reinspection fee
Charged when applicable; see current fee schedule
06
Penalty (no permit)
Penalties apply for construction without permit; consult county office
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 periodically. Confirm at the official fee schedule ↗ (effective Updated annually in September) before budgeting.
§ 05
Required inspections
Scheduling and sequence
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 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.
Source: Mason County Community Development Department, Building Division ↗
§ 06
Frequently asked
Common questions about unincorporated Mason County permits
01 Do I need a building permit in unincorporated Mason County, WA? ▸
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.
02 How much does a building permit cost in unincorporated Mason County, WA? ▸
Building permit fees in unincorporated Mason County, WA are set by the local building department and vary by project type and valuation. The minimum permit fee is $156.00. Fees are calculated as: 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. Plan check fee: 65% of building permit fee (collected at submittal).
03 How do I apply for a building permit in unincorporated Mason County, WA? ▸
To apply for a building permit in unincorporated Mason County, WA, follow these steps: 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.
04 How long does it take to get a building permit in unincorporated Mason County, WA? ▸
Building permit processing times in unincorporated Mason County, WA typically run Varies based on project complexity and review comments. Budget 3-6 weeks for standard residential permits.. Timelines can vary based on project complexity and current department workload.
05 What work is exempt from building permits in unincorporated Mason County, WA? ▸
Not all construction work requires a permit in unincorporated Mason County, WA. The following work is generally exempt: 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). Note: 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. When in doubt, confirm with the local building department before starting work.
06 How do I schedule a building inspection in unincorporated Mason County, WA? ▸
Once your permit is issued and work reaches an inspection milestone, you can schedule a building inspection in unincorporated Mason County, WA via: (360) 427-9670, Extension 352, SmartGov Portal, Building Department at 615 W Alder Street. Requests received prior to 3:00 PM confirmed same business day; requests after 3:00 PM processed next business day..
last verified April 2026
source Mason County Community Development Department, Building Division ↗
entry id permits/washington/mason/unincorporated
Educational reference. Permit rules and fees change — confirm current requirements directly with Mason County Community Development Department, Building Division before applying. Jaspector is not legal advice.