Permit Requirements for Union, Washington

For Plumbing projects in Union, determining the correct permitting authority depends on whether the project site is located within the incorporated city limits or in an unincorporated area of Mason County.

Authority Having Jurisdiction (AHJ)

Most jurisdictions require permits for Plumbing work to ensure safety and code compliance. The governing body responsible for issuing these permits varies by specific location:

General Plumbing Guidelines

Permits are usually required for new installations, structural modifications, or major repairs. While minor maintenance or cosmetic updates may be exempt, landowners should always verify local codes before work begins.

Because Union is located within Mason County, the following broader county regulations may also apply to your project:

Washington, Mason County Plumbing Permit Regulations and County Ordinances for Unincorporated Areas

Mason County Building and Safety Division

Mason County, Washington, has a Community Development Department that oversees building permits, including plumbing. For properties in unincorporated areas, a building permit is generally required for most construction activities. This includes plumbing work. All contractors must be registered with Washington State L&I. Owner-builders may apply but must adhere to all code and registration requirements.

The county adopts and enforces the 2021 Uniform Plumbing Code (UPC), along with other relevant building codes such as the International Building Code (IBC) and International Residential Code (IRC), as amended by Washington Administrative Code (WAC) and local ordinances.

Plumbing Permit Requirements for Unincorporated Areas

To obtain a plumbing permit in unincorporated Mason County, you will typically need to submit a plumbing/mechanical permit application along with other required documents. These may include:

Approved site plans and building plans are required to be on-site during inspections.

There is no additional mail-in fee for electrical, mechanical, or plumbing permits, though building permits obtained by mail may incur a $25 administrative fee.

Permits can be applied for online through the SmartGov Portal or in person by appointment at the Permit Center.

Resources to Learn More

The following statewide building codes and regulations apply universally to all jurisdictions within Washington:

Washington Plumbing Legislation, Codes, and Guidelines

Plumbing Codes and Legislation in Washington State

The state of Washington regulates plumbing systems through the adoption of the 2021 Uniform Plumbing Code (UPC), which is published by the International Association of Plumbing and Mechanical Officials (IAPMO). This model code is adopted by reference and modified by state-specific amendments to create the Washington State Plumbing Code, codified under Chapter 51-56 of the Washington Administrative Code (WAC). These regulations are established under the authority of the Revised Code of Washington (RCW) Chapter 19.27, which governs the State Building Code.

Primary State Agencies

Two primary state entities oversee the plumbing regulatory framework in Washington:

It is important to note that while the state sets the minimum standards, local jurisdictions (cities and counties) are responsible for issuing permits and conducting inspections. Local authorities may also adopt additional, stricter amendments to the state code.

Resources to Learn More

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