Do You Need a Retaining Wall Permit in Spokane?

Whether a retaining wall needs a permit around Spokane comes down to three questions: which jurisdiction the property is in, how tall the wall is from the bottom of its footing, and what the wall holds back. The City of Spokane, the City of Spokane Valley and unincorporated Spokane County don't word their rules the same way, and the differences show up most on the short garden walls people assume never need a permit.

Start with the jurisdiction

A Spokane mailing address doesn't mean a property is inside Spokane city limits. The City says so on its residential permit process page and points owners to Spokane County's SCOUT property dashboard, which shows the jurisdiction for an address. Mead and Colbert, for example, are in unincorporated Spokane County, so the County's rules apply there, while Spokane Valley runs its own permit center.

Inside the City of Spokane

The City's guide sheet BUILD-08, Earth-Retaining Structures, starts from the opposite end of most people's assumption. It says a building permit and plan review are required for earth-retaining structures, that the plans must carry the seal of a Washington-licensed professional, and that a geotechnical analysis may be required. Then it lists three exceptions:

• Reinforced concrete walls up to three feet above grade, with the footing as deep below grade as the wall is tall above it, level backfill and no surcharge.
• Any earth-retaining wall up to four feet from the bottom of the footing to the top of the wall, as long as it stands at least 15 feet from property lines.
• Modular block walls up to four feet from the bottom of the footing, built to the manufacturer's published guidelines, backfilled with clean gravel or crushed rock, carrying no surcharge, and limited to two terraces set at least twice the wall height apart.

The middle exception is the one that catches people. A boulder or stacked-stone wall isn't modular block, so if it sits within 15 feet of a lot line it doesn't clearly fit any of the three. Confirm that kind of wall with the City's Development Services Center before it's built. When a permit is needed, the City also lists earth-retaining structures among the work that calls for drawings and calculations stamped by a Washington-licensed engineer (SFR-20).

Spokane Valley and unincorporated Spokane County

In Spokane Valley and the unincorporated county, the four-foot rule most people know is the one that applies. Washington adopts the 2021 International Residential Code statewide under WAC 51-51-003, and its section R105.2 exempts a retaining wall up to four feet, measured from the bottom of the footing to the top of the wall, unless it supports a surcharge. Spokane County's permit exemption handout, BP-25, lists the same limit, and Spokane Valley's local amendments in SVMC 24.40.040 leave it as written. If a wall in Spokane Valley is close to the line, the City of Spokane Valley's permit center can confirm it.

Spokane Valley adds a separate layer for earthwork. Under its land disturbance rules, excavation, fill and grading need a permit unless exempt. A project that is only a wall under four feet high is exempt, but Spokane Valley's land disturbance checklist calls for a regular grading permit when excavation or fill passes 50 cubic yards on a lot, when a cut is deeper than three feet or a fill higher than two, or when either is sloped 2:1 or steeper. Grading in a geologically hazardous area, or cuts and fills at 2:1 or steeper and more than two and a half feet high, needs an engineered grading permit.

How height is measured

All three jurisdictions measure the four-foot limit from the bottom of the footing to the top of the wall, so the buried part counts. A wall that shows three and a half feet above the lawn can pass four feet once its footing and the courses below grade are added.

Terraces need care too. Inside the City, the block-wall exception allows two tiers, each up to four feet, only when the gap between them is at least twice the wall height. Closer than that, the upper wall adds load to the lower one, and the exception no longer applies.

What counts as a surcharge

A surcharge is load on or behind the wall beyond the level ground it retains. BUILD-08 names parking areas, walkways, structural loads and sloping backfill. In practice that means a driveway or parking pad at the top of the wall, a path or patio along its edge, a structure's footing close behind it, or a hillside that keeps rising above it.

In Spokane Valley and the county, a wall carrying a surcharge needs a permit at any height. Inside the City, the concrete and block exceptions don't apply to one.

Drainage and slopes

Water behind a wall adds pressure the soil alone doesn't. That's why BUILD-08's block-wall exception asks for clean gravel or crushed rock as backfill: it lets water drain to the outlet instead of collecting. Where that water ends up matters as much, so the outlet goes somewhere it won't erode the slope below or run onto a neighbor's yard.

Slopes bring their own rules inside the City. The geologically hazardous areas code, SMC 17E.040.030, classes slopes of 30 percent or more as landslide hazard areas and names retaining walls that lean downslope or have broken as a sign of creeping ground. Clearing and grading in those areas, even 50 cubic yards or less, falls under the City's critical areas rules and starts with a critical areas checklist (SMC 17E.040.050). The City has also adopted the grading appendix of the International Building Code (SMC 17F.040.020), so a large cut or fill can need a grading permit of its own.

What our design accounts for

A Cross Creek retaining wall design starts with the jurisdiction, then works out each wall's full height from the bottom of the footing, the loads above it and where its water goes. In practice that means:

• Walls laid out so a short wall stays short, with terraces spaced to suit the slope where they work better than one tall wall.
• Paths, patios and driveways kept back from wall tops, or the wall designed to carry them.
• Backfill, drains and outlets drawn into the plan, not left to be worked out on site.
• Sealed plans from a Washington-licensed professional where the permit calls for them.
• Utility locates through 811 at least two full business days before digging, as RCW 19.122.030 requires.

Walls are also placed with the rest of the yard in mind, so the patio, steps and planting above and below them work as one space. That's the job of the landscape design.

If you're planning a wall in Spokane, Spokane Valley or anywhere else in Spokane County, start with a free on-site consultation. Call our Spokane office at (509) 352-3433 and we'll come look at the slope with you.