King County Washington Residential Solar Permit Guide

King County residential rooftop solar may be exempt from a building permit when it stays within specific dead-load and roof-mounting limits, but electrical permits still run through Washington State Labor and Industries.

Permit takeaway

King County's solar guide says some single-family, duplex, and townhouse rooftop systems do not need a King County building permit when panel dead load and mounting height stay within the listed limits.

Zoning and placement

Solar panels must still meet local zoning height rules, roof constraints, and any shoreline, critical area, or property-specific limits.

Building and trade review

Systems outside the exempt criteria can require an application, drawings, manufacturer specifications, and structural engineering calculations when applicable.

Call before applying when

Call before applying if the panels are mounted more than 18 inches above the roof, the dead load exceeds the exemption threshold, the property is multifamily, or the work includes roof or electrical upgrades.

Documents to prepare

• Solar system description
• Roof plan
• Manufacturer specifications
• Exempt checklist if applicable
• Structural calculations when required

Inspection planning

• Confirm exemption eligibility
• Keep exempt checklist records when allowed
• Apply for King County building review when required
• Coordinate Washington electrical permit
• Complete final inspection or approval steps

Official sources

• King County Solar Incentives and Permit Process Guide
• King County Solar Exempt Permit Checklist
• King County Permits

This guide is a planning summary. Always verify the current requirements with the local office before starting work.