Common Building Permit Types

Understanding which permits your project requires is the first step toward a successful build. Below is an overview of the most common building permit types in Washington State, along with typical costs, timelines, and requirements.

Accessory Dwelling Unit (ADU) Permits

ADUs are self-contained living units built on the same lot as an existing single-family home. They include basement conversions, attached additions, and detached backyard cottages (sometimes called DADUs). ADUs have become increasingly popular across the Puget Sound as a way to add housing, generate rental income, or create space for family members.

• Typical cost: $2,000 - $8,000+ in permit and impact fees, depending on jurisdiction and project size
• Typical timeline: 8-16 weeks for plan review in Seattle; 6-12 weeks in Tacoma and other jurisdictions
• Requirements: Site plan, building plans, energy code compliance, and compliance with local ADU regulations (size limits, setbacks, parking, owner occupancy where applicable)

Deck and Patio Permits

In most Washington jurisdictions, decks that are more than 30 inches above grade require a building permit. Covered patios, pergolas attached to the house, and elevated walkways also typically require permits. Ground-level patios and floating decks under 30 inches may be exempt, but setback and lot coverage rules still apply.

• Typical cost: $150 - $500 in permit fees for a standard residential deck
• Typical timeline: 1-4 weeks depending on jurisdiction
• Requirements: Site plan showing deck location, structural plan with footing details, and compliance with setback requirements

Remodel and Renovation Permits

Most interior and exterior remodeling work that involves structural changes, moving walls, changing window or door openings, or modifying electrical, plumbing, or mechanical systems requires a building permit. Common projects include kitchen remodels, bathroom renovations, basement finishes, and room additions.

• Typical cost: $500 - $5,000+ depending on project scope and construction value
• Typical timeline: 3-8 weeks for plan review, depending on project complexity and jurisdiction
• Requirements: Floor plans showing existing and proposed conditions, structural details where applicable, and trade permit applications for electrical, plumbing, and mechanical work

Do I need a permit for cosmetic work? Purely cosmetic changes like painting, replacing flooring, or installing cabinets in the same footprint generally do not require a permit. However, if the work involves any electrical, plumbing, or structural changes, a permit is required.

Electrical Permits

Electrical permits are required for most electrical work beyond simple fixture replacements. This includes panel upgrades, adding new circuits, rewiring, EV charger installation, generator hookups, and electrical service changes. In Washington State, homeowners can pull their own electrical permits for their primary residence, but the work must still pass inspection.

• Typical cost: $75 - $300 for most residential electrical permits
• Typical timeline: Often same-day or within a few days for standard residential work
• Requirements: Description of work, load calculations for panel upgrades and service changes

Plumbing Permits

Plumbing permits are required for new fixture installation, re-piping, water heater replacement, sewer line repair, and gas piping. Like electrical permits, homeowners in Washington can pull their own plumbing permits for their primary residence.

• Typical cost: $75 - $250 for most residential plumbing permits
• Typical timeline: Often same-day or within a few days
• Requirements: Description of work, fixture count for new installations

Mechanical (HVAC) Permits

Mechanical permits cover heating, ventilation, and air conditioning work. This includes furnace replacement, heat pump installation, ductwork modifications, and mini-split installations. A mechanical permit ensures the system is installed safely and meets energy code requirements.

• Typical cost: $75 - $300 for most residential mechanical permits
• Typical timeline: Often same-day or within a few days
• Requirements: Equipment specifications, duct layout for new installations

Roofing Permits

Roofing permits are required in most jurisdictions when replacing a roof. Some jurisdictions allow re-roofing over one existing layer without a permit, but a full tear-off and replacement typically requires one. The permit ensures proper underlayment, flashing, and ventilation.

• Typical cost: $100 - $300
• Typical timeline: Same-day to 1 week
• Requirements: Scope of work, roofing materials specification

New Construction Permits

Building a new home or commercial structure requires a comprehensive building permit that encompasses structural, electrical, plumbing, mechanical, and energy code review. New construction permits are the most complex and involve the most extensive plan review process.

• Typical cost: $5,000 - $30,000+ in total permit and impact fees, depending on project size and jurisdiction
• Typical timeline: 2-6 months for plan review
• Requirements: Complete architectural plans, structural engineering, energy code documentation, site plan, and potentially environmental review

Permit Quick Reference

Permit Type	Typical Fee	Review Time
ADU / DADU	$2,000 - $8,000+	6-16 weeks
Deck / Patio	$150 - $500	1-4 weeks
Remodel	$500 - $5,000+	3-8 weeks
Electrical	$75 - $300	Same day - 1 week
Plumbing	$75 - $250	Same day - 1 week
Mechanical / HVAC	$75 - $300	Same day - 1 week
Roofing	$100 - $300	Same day - 1 week
New Construction	$5,000 - $30,000+	2-6 months

Note: Fees and timelines vary by jurisdiction. The figures above are general estimates for the Puget Sound area. Call us for a project-specific estimate.