Do I Need a Permit for a Deck in Clackamas County?

In Clackamas County, a deck more than 30 inches above grade needs a building permit; a deck built lower than that generally doesn't trigger the county's structural permit requirement. If you're near a septic system, decks over that 30-inch line also have to keep a minimum distance from the tank and drain field. Confirm your exact address's jurisdiction — county or city — before you apply.

The 30-inch rule

Clackamas County treats a deck as a "structure" once it's built more than 30 inches above grade, and structures need a building permit. That threshold is what most homeowners run into first: a low ground-level deck, a few inches or a foot off the yard, usually doesn't need a permit. A raised deck off the back of a house, common on sloped Sandy-area lots, almost always crosses the 30-inch line and does. Measure from the finished ground level to the top of the deck surface, not just eyeball it — a deck that looks "not that high" can still clear 30 inches once you account for the slope of the yard underneath it.

Setbacks if you have a septic system

If your property is on a septic system, which is common outside Sandy's city limits, decks over 30 inches have specific setback rules per the county's deck setback guide:

• At least 5 feet from the septic tank, measured from the deck's pier blocks or other supporting devices.
• At least 10 feet from the drain field.
• A cantilevered deck can extend partially over the tank or field as long as the actual support posts stay outside those distances.
• Regardless of height, no deck can block access for septic tank pumping or drain field repair.

Decks under 30 inches don't carry those same setback distances under this guidance, but you still shouldn't build directly over a tank or field — a truck needs to get in there eventually.

What the permit-ready deck plans cover

Oregon's Building Codes Division publishes a set of permit-ready deck plans built to the current Oregon Residential Specialty Code. They cover single-span deck joists (with or without a cantilever) within set limits for wind speed, seismic category, and load, and they restate the same exemption: a deck where the walking surface is not more than 30 inches above adjacent grade, measured at any point within 3 feet of the walking surface, is exempt from a permit. If your deck fits those standard parameters, the permit applicant can use the pre-engineered tables and details instead of hiring a separate engineer to stamp a custom design, which usually moves the permit through faster. Ask whoever is pulling your permit whether your design matches one of these standard plans.

What needs a permit beyond the deck itself

The county's general building permit page covers structural work broadly — new construction, additions, and alterations — along with mechanical, electrical, and plumbing work that often comes with a deck project, like a new electrical circuit for outdoor lighting or a gas line for a built-in grill. If your deck project includes any of that, expect more than one permit type in the mix, and ask your contractor to account for each one.

Sandy city limits vs. unincorporated county

Whether you go through the county or the city depends on where your property sits. Sandy is its own incorporated city with its own planning and building process, separate from Clackamas County's unincorporated areas. A lot inside Sandy's city limits goes through the City of Sandy; a lot outside city limits, out toward Marmot, Cherryville, or Government Camp, generally goes through Clackamas County. If you're not sure which jurisdiction covers your address, check with the county or city directly before assuming the rules above apply as written — city rules can differ from the county's.

Who pulls the permit

Either the homeowner or the contractor can apply for a permit, but only one of you should, and it should be settled before work starts. Ask your contractor directly: will you pull the permit, and is that cost already built into your bid? A bid that's noticeably cheaper because it skips the permit isn't actually a cheaper deck — it's an unpermitted structure that can complicate a home sale, a refinance, or an insurance claim later, since it was never inspected or recorded.

Getting a straight answer for your property

The rules above are the general framework, but every lot is different — slope, septic location, flood zone overlays, and whether you're in city or county jurisdiction all matter. The county recommends contacting Planning or the Development Services Building directly to confirm what applies to your specific property before you finalize a design or sign a bid.