Decks and permits
Deck and Deck Cover Permits in Olympia, Lacey and Tumwater (2026)
The short answer
A deck escapes a building permit in Washington only if all four of these are true at once: it is 200 square feet or less, it is 30 inches or less above grade at every point, it is not attached to the house, and it does not serve the required exit door. Fail any one and you need a permit.
A roof over that deck is a separate question, and the answer is almost always yes. Tumwater names "patio or deck roof cover" directly on its permit-required list. A cover can pull a deck into permit territory even when the deck by itself would have been exempt.
The four-part rule that decides it
Washington builds on the 2021 International Residential Code. The section listing work exempt from a permit is R105.2, and the state left it unamended, so it applies here as written.
For decks it sets four conditions.
| Condition | Exempt if |
|---|---|
| Size | 200 square feet or less |
| Height | 30 inches or less above grade at any point |
| Attachment | Not attached to the dwelling |
| Egress | Does not serve the exit door required by R311.4 |
These are not alternatives. They stack.
A 12 by 16 foot deck is 192 square feet and clears the size test. But bolt it to the house and it fails the attachment test, so it needs a permit anyway.
A ground-level platform two inches off the dirt still needs a permit if it is the landing for your back door.
The one people miss
Height is measured at any point, not on average. A deck that sits flush with the back door and steps down across a sloping yard can be 8 inches high at one end and 40 inches at the other. That deck needs a permit. Thurston County lots in Tumwater and south Olympia slope more often than not.
What each jurisdiction actually says
Cities can be stricter than the state baseline, and some are. Here is what each one publishes, checked on 7 October 2026.
| Where you are | What they publish |
|---|---|
| Tumwater | No permit for "platforms, decks and walks 30 inches high or lower above grade that are not attached to a dwelling". Note there is no square footage limit in that wording, unlike the state rule. Permit required for decks, and separately for "patio or deck roof cover". |
| Unincorporated Thurston County | No permit for "decks, patios and porches if 30 inches or less from ground to top of deck". Permit required if "more than 30 inches tall from the ground, including adding walls". Roofs need a permit "only if enlarging a roof, or changing its pitch/slope". |
| Olympia | Applies the state residential code. Its "Do I need a permit?" page lists unroofed decks as exempt only when they are 200 square feet or less, no more than 30 inches above grade at any point, not attached to a dwelling and not serving the required exit door. Confirm your project with the Permit Center on 360.753.8314 before you order materials. |
| Lacey | Applies the state residential code. Lacey issues some simple permits over the counter, such as residential re-roofing and re-siding, and decks are not among its examples. Call the city before you build. |
Tumwater and unincorporated Thurston County both hang their exemption on the 30 inch height and on whether the deck is attached. Neither applies a square footage cap the way the state rule does.
That is a real difference. A large, low, freestanding deck that would need a permit under a strict reading of the state rule is exempt under what Tumwater publishes.
Deck covers are a different question
This is where most of the bad advice online sits. People read the 30 inch rule, see their deck is low, and assume a roof over it is fine too.
The 30 inch rule describes the height of the deck surface. It says nothing about what you put above it.
Tumwater removes the doubt by listing patio or deck roof cover as work that requires a building permit, with no size or height qualifier.
Thurston County does not list patio covers at all. But it does require a permit for enlarging a roof, which is what an attached deck cover does.
Why a cover is treated seriously here
- Snow load. A roof has to carry weight that an open deck never sees, and western Washington lowland design loads are not trivial.
- Wind uplift. A flat roof surface eight feet off the ground behaves like a wing in a winter storm.
- Lateral load. Bolting a roof to the house changes how the whole assembly moves in an earthquake, and this region is seismic design category D.
- Drainage. A new roof adds impervious surface, which cities track separately from building coverage.
Pergolas are not automatically exempt
An open slatted pergola and a solid patio cover get treated differently in some jurisdictions and identically in others. If the roof surface is solid, or even partially solid, expect it to be treated as a patio cover. Louvered systems that close are solid roofs when closed. Ask before you buy the kit.
What it costs to permit, and what drives the number
Nobody can quote you an exact permit fee from a blog post, because the fee comes from the valuation of the work, not a flat price list.
Olympia sets building permit and plan review fees from the International Code Council valuation data, under OMC 4.36.010, then adds a technology fee of 4.1 percent on top of permit and plan review fees.
So the permit cost scales with the project. A larger or more complex deck costs more to permit, and a cover costs more than the deck alone, because it adds valuation and usually adds structural review.
What the build itself costs is a separate question. We covered that in what a deck or deck cover costs in Thurston County.
What you will be asked for
Expect the permit desk to ask for most of the following. Each jurisdiction has its own checklist, so ask for the current one.
- A site plan showing the building footprint, setbacks, and the deck or patio area in square feet
- Total building coverage, existing and proposed
- Total impervious surface and total hard surface, existing and proposed, in square feet
- Total projected roof area, which is where a cover starts to matter
- Structural calculations and engineered drawings where the span or the roof requires them
The mistakes that cost money
- Measuring height at the door instead of at the lowest point of a sloping yard.
- Assuming a freestanding deck stays freestanding. A ledger board bolted on later changes the answer retroactively.
- Treating a cover as a deck accessory rather than as a roof.
- Forgetting the exit door test. If the deck is the landing for the required egress door, no exemption applies at any height.
- Building to the square footage limit and ignoring setbacks, which are a separate zoning question from the building permit.
- Not counting the new roof area against impervious surface limits on a lot that is already close to the cap.
A short checklist before you start
- Measure the height at the lowest point of the finished grade, not the average.
- Decide now whether the deck attaches to the house, because it changes the permit answer.
- Check whether the deck serves the required exit door.
- If there is any roof in the plan, assume you need a permit and price it in.
- Confirm your setbacks with the city or county, separately from the building permit.
- Call the permit desk with your actual numbers before ordering materials.
Common questions
Do I need a permit for a deck in Olympia?
Olympia applies the Washington state residential code, which exempts a deck only when it is 200 square feet or less, 30 inches or less above grade at every point, not attached to the dwelling, and not serving the required exit door. Most real decks fail at least one of those. Confirm your project with the Olympia Permit Center on 360.753.8314.
What size deck can I build without a permit?
Under the state rule a deck is exempt only if it is 200 square feet or less, 30 inches or less above grade at every point, not attached to the house, and not serving the required exit door. Some local lists, including Tumwater, word the exemption around the 30 inch height and whether the deck is attached, with no square footage limit. Most real decks fail at least one test, so confirm with your city before you build.
Does a deck cover need its own permit?
In Tumwater, yes. The city lists "patio or deck roof cover" as work that requires a building permit, with no size exemption. Elsewhere in Thurston County a cover attached to the house enlarges the roof, which also requires a permit. Treat a cover as needing a permit unless the jurisdiction tells you otherwise in writing.
What is the 30 inch deck rule in Washington?
It is one of four conditions in the state residential code that must all be true for a deck to skip a permit. The deck must be no more than 30 inches above grade at any point. Height is measured at the lowest point, so a deck on a sloping lot often fails this test even when it looks low at the house.
Is a pergola exempt from a permit?
Not reliably. Olympia only exempts unroofed decks, and Tumwater lists any patio or deck roof cover as needing a permit, so a solid or partly solid roof should be treated as needing one. A louvered pergola that closes is a solid roof when closed. Check with your jurisdiction before you buy a kit.
How much does a deck permit cost in Olympia?
There is no flat fee. Olympia calculates building permit and plan review fees from International Code Council valuation data under OMC 4.36.010, and applies a technology fee of 4.1 percent on top. The fee scales with the valuation of the work, so a covered deck costs more to permit than an open one.
Can I build the deck first and permit it later?
You can apply for a permit on existing work, but it is the expensive route. Inspectors cannot see covered framing or footings once the decking is down, so you may be asked to open the work up. Permit first.
Where to go from here
Planning a deck or a cover in Olympia, Lacey, Tumwater or anywhere else in Thurston County? We handle the permit work as part of the build rather than leaving it with you.
Tell us the site and what you want, and we will tell you straight away which side of these rules your project falls on.
Code requirements on this page were last checked on 7 October 2026. Codes change, so confirm current standards with your city or county before you apply.
Planning a deck in Thurston County?
We handle the permit work as part of the build. Tell us the site and what you want.
Where this applies
We work in every one of these towns, and each has its own page covering the rules that apply there.