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Building Development Center

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Why Permits and Inspections are Necessary

Before You Build Guide (PDF)

guide boxThis page is referenced in our Step by Step Guide for Home Builders.

Projects that Require a Building Permit

building permitYou can safely assume that all construction activity, from initial grading of a site to interior improvements, alterations and most repairs, requires a building permit. However, there are exemptions for small detached structures and ordinary repairs. (The Thurston County Building Development Center issues permits for development in unincorporated Thurston County only. If your project is within city limits, please contact the city instead.)

If you are unsure whether you need a building permit for a project in Thurston County, please call the Permit Assistance Center at (360) 786-5490 or TTY/TDD call 711 or 1-800-833-6388.

red blinking arrowNote: This page focuses on residential building permits.  If you plan to develop land that contains critical areas or shorelines, or to subdivide property, please see our web pages on Land Use Ordinances and Land Use Applications.  If you are proposing a nonresidential (commercial) project, click here.

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Projects that Require a Building Permit

Generally speaking, a permit is required if you are starting a new construction project, remodeling and planning to change the footprint of an original structure, changing the roof pitch, or making any structural changes. Before seeking a permit, though, you should make sure that your project is actually allowed in the area in which you are building.

 For example, a building permit is required if you are:

Building or installing:

  • A new structure unless it is exempt.  Click here for more information.
  • Porches, decks and patios that are more than 30 inches above grade (see below)
  • Cover to a patio or deck
  • Chimneys
  • Garages and carports unless it is exempt.  Click here for more information.
  • First time installation of fixtures and appliances permanently connected to the electrical, mechanical, gas and/or plumbing system(s). Approval typically happens as part of the inspection process.
  • Fences and privacy walls higher than 8 feet.
  • Sheds that are attached to a house.
  • Sheds or playhouses that are detached if they are greater than 200 square feet.
  • Swimming pools 24 inches deep or more (see below)
  • Attic pull-down stairs
  • Retaining walls supporting more than 4 feet of earth.
  • Skylights

Adding to or changing:

  • Attics, finishing
  • Basements, build or enlarge
  • Rooms
  • Dormers, bay windows or other wall openings
  • Water heater or any other parts of the plumbing
  • Furnaces and any other parts of the heating and gas system
  • Circuits or any other parts of the electrical system (click here for information about electrical permitting).
  • Walls to a porch
  • Garage to livable area

Repairing or replacing:

  • Structural Roof Repairs
  • Replacing siding/foundation
  • Existing stone, brick or concrete

Projects that Do Not Require a Building Permit

Permits are not required for the following when related to single-family homes, provided do not encroach over a subsurface drain system, public utility easement, or into buffers or required setbacks from property lines:

  • One-story detached accessory structures.  Click here for more information.
  • Fences not over 8 feet (2438.4) high measured from the highest point to grade.
  • Oil derricks.
  • Retaining walls that are not over 4 feet in height measured from the bottom of the footing to the top of the wall, unless they support surcharge (ie, holding back a load, such as a slope) or impounding Class I, II or IIIA liquids (ie, flammable liquids).
  • Water tanks supported directly on grade if the capacity does not exceed 5,000 gallons and the ratio of height to diameter or width does not exceed 2 to 1.
  • Sidewalks and driveways not more than 30 inches above adjacent grade, and not over any basement or story below and are not part of an accessible route (ie, an access route required under the Americans with Disabilities Act).
  • Painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work
  • Temporary motion picture, television and theater stage sets and scenery.
  • Prefabricated swimming pools accessory to a Group R-3 occupancy that are less than 24 inches deep, do not exceed 5,000 gallons and are installed entirely above the ground. Group R-3 refers to one and two-family dwelling units, or adult and child care facilities that provide accommodation for five or fewer persons of any age for less than 24 hours.
  • Temporary growing structures for commercial production constructed with the roof and side of polyethylene, polyvinyl or similar flexible synthetic material, used to provide plants with either frost protection or increased heat retention. For commercial growing, this is pursuant to WAC 51-50-007.
  • Swings and other playground equipment accessory to detached one- and two-story family dwellings.
  • Window awnings supported by an exterior wall which do not project more than 54 inches from the exterior wall and do not require additional support of Groups R-3 and U occupancies. Group R-3 refers to one and two-family dwelling units, or adult and child care facilities that provide accommodation for five or fewer persons of any age for less than 24 hours.
  • Non-fixed, movable fixtures, cases, racks, counters and partitions not over 5 feet 9 inches (1753 mm) in height constructed under the International Building Code.
  • Replacement of roof coverings.
  • Patios or decks not more than 30 inches above the adjacent grade that are accessory to structures constructed under the International Residential Code.

Typical home improvement projects that do not require a permit

  • Ceramic, tile, hardwood floors, carpet.
  • Crown molding, baseboards, trim.
  • Replacement of a glass or glazing within an existing window pane or a door within the existing frame. If you are widening or changing the door frame or window frame, you will need a permit.
  • Gutters and down spouts.
  • Kitchen cabinets (new and existing)
  • On-grade patios, decks and porches
  • Recreational equipment (swings, jungle gyms, skateboard ramps, etc.)
  • Small-scale roof repairs
  • Detached sheds or playhouses that are 200 square feet or less in size. Note: You must still meet setback requirements per the zoning ordinance (see Chapters 20, 21, 22 and 23).

Projects that Do Not Require a Gas (Minor) Permit:

  • Portable heating device
  • Portable ventilation equipment
  • Portable cooling unit
  • Steam, hot or chilled water piping within any heating or cooling equipment
  • Replacement of parts
  • Portable evaporative cooler
  • Self-contained refrigeration system containing 10 pounds or less of refrigerant and actuated by motors of 1 horsepower or less.

Projects that Do Not Require a Plumbing (Minor) Permit:

  • The stopping of leaks in drains, water, soil, waste or vent pipe, provided, however, that if any concealed trap, drain pipe, water, soil, waste or vent pipe becomes defective and it becomes necessary to remove and replace the same with new material, such work shall be considered as new work and a permit shall be obtained and inspection made as provided in this code.
  • The clearing of stoppages or the repairing of leaks in pipes, valves or fixtures and the removal and reinstallation of water closets, provided such repairs do not involve or require the replacement or rearrangement of valves, pipes or fixtures.

Projects that do not require a mechanical Permit:

  • Portable ventilation appliances, evaporative coolers, independent fuel cell appliances, heating appliances and cooling units.
  • Piping within any heating or cooling code regulated heating equipment.
  • Replacement of minor parts.
  • Replacement of an existing forced air hearing or electric heat pump.


Be sure to visit our FAQs page for answers to common questions we receive at the Building Development Center.

Contact Us

     Phone: (360) 786-5490. TTY/TDD call 711 or 1-800-833-6388.  E-mail: permit@co.thurston.wa.us.


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