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FAQ - Required Permits

How can I tell whether a permit is required?

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. It's better to assume that you need a permit and check with the Building Development Center rather than proceed on a project and find out later that it is not in compliance. Click here for general guidance, and please feel free to contact us if you have questions.

How do I know what the submittal requirements are?

Every application includes a list of submittal requirements.  You will see those requirements when you open the application PDF. 


Click here for information on exempt structures.


In unincorporated Thurston County, a building permit is required to construct a deck or walking surface more than 30 inches above the grade. (In other words, if the distance from the ground to the top of the deck is more than 30 inches.) Decks must be built according to the International Residential Code. For a drawing, click here.

A deck must have a guardrail when the difference in distance between the deck and the ground plan is greater than 30 inches. For single-family homes, the deck guardrails must be at least 36 inches high.

Also, deck stairs require a handrail when there are four or more stair risers. The handrails must be between 34 inches and 38 inches above the stair tread.

Deck guardrails and stair handrails require openings no greater than 4 inches along the railing surface, although the rail can have a 6-inch gap at the base of the railing and a stair riser.

Deck guardrails and handrails must be able to support a load of 50- lbs per linear foot from any direction.  So, a railing must be able to bear the load laterally, that is from the side, as well as from the top.


In unincorporated Thurston County, you may build an eight foot fence or shorter without the need to obtain a building permit. The fences can be located up to the property line except at street intersections or access points. If your fence will be more than eight feet tall, click here for permit applications (SA 001).  For information on how to measure a fence click here.

At intersections (street corners) and access points (driveways), a site distance triangle must be maintained for traffic safety reasons. Click here (page 34) for an illustration of Thurston County's required site distance triangle. For more information about fencing along corner lots, call Thurston County Development Services in the Public Works Department: (360) 867-2050.

Barbed or razor fencing is not allowed in some residential zones.

Retaining/Landscape Walls

Retaining walls and landscape walls look similar but retaining walls require a permit and a design by a licensed design professional.  Please click here for information to determine if the wall you want to build requires a permit.  If your wall requires a permit, click here for permit applications (SA 001).


No permits required for replacement of roof coverings (re-roofing), but the replacement must comply with the building code. You still need a permit if adding skylights, repairing or replacing structures or making any other structural changes.

Garages & Carports

 Click here for an application and information bulletin (SA 001). Click here for information on exempt structures.

Pools & Hot Tubs

Click here for Residential pool and spa information.

Air Conditioner/Heat Pump

Mechanical (SA 006) and electrical permits are required and the unit may not be set within established yard setbacks; however, permits are not needed for:

  • Portable heating devices (space heaters)
  • 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.

Concrete Slabs, Walks, Driveways, Patios

No building permit is required in unincorporated Thurston County, provided they are 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).

An encroachment permit (SA 013) is needed to connect to a county-owned road. A right-of-way access permit (SA 015b) is required if working in a county unopened right-of-way.

Doors and Windows

No permit is required to replace the 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 to fill out a minor permit application (SA 006) and contact the Building Development Center for code requirements.

Plumbing - Fixture Replacement

No permit is required to stop leaks in drains, water, soil, waste or vent pipes.  If they become defective and must be removed and replaced with new material, customers need to fill out a minor permit application (SA 006).

Adding plumbing to an accessory building requires a site plan that meets Thurston County's site plan submittal requirements and additional review by Thurston County Environmental Health (360) 754-3355 ext. 2676.

Furnace, Gas Insert, Gas Log, Woodstoves

Mechanical permits are required for all these appliances (SA 006 minor permit) and may also require electrical permits if wiring work is needed. A permit is not needed for portable heating appliances (space heaters), or to replace any minor parts.

Retaining Walls

In unincorporated Thurston County, no building permit is required if the wall is 4 feet or less in height from the bottom of the footing to the top of the wall and not supporting an extra load such as a fence or soil sloping down to the top of the wall; otherwise, a building permit is needed (SA 001).

Shelving and Cabinets

No building permit required.

Siding Replacement

No building permit required.

Water Heaters

A plumbing permit is required to replace a water heater. A new installation will also require a mechanical permit if it is gas-heated.  The permit application for plumbing and mechanical permits is SA 006 (minor permit).


Click here for information about dock repairs and installations in fresh water (lakes).

Contact Us

Thurston County Building Development Center, 2000 Lakeridge Drive SW, Olympia, WA 98502-6045.
Phone: (360) 786-5490. TTY/TDD call 711 or 1-800-833-6388  E-mail: permit@co.thurston.wa.us.


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