Retaining Wall Contractor in Nine Mile Falls, WA: Poured Concrete & Block Walls

Poured concrete and block retaining walls in Nine Mile Falls, WA, built for the county your parcel is in and the slopes along the Spokane River. Raven Buildings excavates, forms, pours and backfills retaining walls for sloped lots, driveway cuts, patios and shop pads across Nine Mile Falls, Suncrest and the Lake Spokane shoreline, on both the Spokane County and Stevens County sides of the river.

Retaining walls we build around Nine Mile Falls

• Poured concrete walls: reinforced cast-in-place walls for driveway cuts, shop pads and taller grade changes
• Block walls: segmental block walls for yards, garden terraces and patio edges
• The work around the wall: excavation, drain rock, perforated drain pipe, and the driveway, patio or slab on top, poured by our own crew
• Walls tied to a bigger job: cutting and leveling a pad on a sloped lot for a shop, pole building or metal building before we build it

Which county issues your permit?

Nine Mile Falls (ZIP 99026) straddles the Spokane River and the Spokane-Stevens county line, so the ZIP code doesn't tell you who issues permits:

• Spokane County parcels: Spokane County Building and Planning
• Stevens County parcels, including Suncrest: Stevens County Land Services, through its Building and Planning divisions

Do you need a permit for a retaining wall?

On the Spokane County side, the County's permit exemption handout (BP-25) spells out the rule:

• No building permit: retaining walls not over 4 feet high, measured from the bottom of the footing to the top of the wall, are exempt
• The surcharge catch: the exemption doesn't apply to a wall that's supporting a surcharge, like a driveway, parking area, a building's footing or a slope that keeps rising behind it, even when the wall is short
• Over 4 feet: a taller wall, or one carrying a surcharge, needs a County building permit
• Exempt doesn't mean anything goes: exempt work still can't sit in setbacks or easements, on utilities, or in the County right-of-way without Public Works approval, and there are added requirements in a critical area such as a steep slope or wetland, or its buffer

On the Stevens County side, we confirm the permit question with Land Services before we dig, and the County's Shoreline Master Program applies to work near Lake Spokane and the river. Because the 4 feet is measured from the bottom of the buried footing, a wall that shows about 3 feet above the ground can already be over the line. Our retaining wall permit guide compares local rules.

When a wall has to be engineered

Washington adopts the International Residential Code statewide. IRC Section R404.4 requires a retaining wall to be designed to accepted engineering practice when it isn't braced at the top and holds back more than 48 inches of unbalanced fill, or when it's over 24 inches tall and carries loads beyond the soil. That design checks overturning, sliding, soil pressure under the footing and water uplift, with a 1.5 safety factor against sliding and overturning. When your wall crosses those lines, we tell you up front and build it to the engineer's design.

Footings below the frost line

• Spokane County side: the joint City of Spokane and Spokane County frost-depth policy (BUILD-07) sets footings at least 24 inches below finished grade unless a soils investigation supports another depth
• Stevens County side: the Stevens County building ordinance sets a 30-inch minimum frost depth for footings exposed to outside temperatures

NOAA's 1991-2020 normals for Spokane International Airport show about 132 nights a year at or below freezing. Water trapped behind a wall freezes, pushes on it and softens the soil under its base, so every wall we build gets:

• Free-draining backfill of clean gravel or crushed rock
• A perforated drain pipe at the base with a real outlet
• Filter fabric between native soil and the drain rock
• Weep holes or drain board on poured concrete walls

Our retaining wall drainage guide and frost depth guide go deeper.

What a Nine Mile Falls retaining wall costs

Every wall is priced from its height, length, material, access and whether it needs engineering, so we quote each one after a site visit rather than publishing a per-square-foot number. Request a free quote with your address and a photo of the slope, and we'll come look.

Why Nine Mile Falls owners call Raven

• One contractor for the wall and the concrete: we pour the driveways, patios, shop slabs and foundations that often sit on top of a wall
• Buildings, too: if the wall is for a shop pad, see our Nine Mile Falls pages for pole buildings and metal buildings. Raven isn't tied to one steel manufacturer, so we source from whichever can deliver fastest
• Nearby, too: we build walls in Spokane, Mead, Spokane Valley and Liberty Lake. Compare materials in our guide to block, poured and boulder walls

Get a Nine Mile Falls retaining wall quote

Call 509-350-2016 or request a free quote. Tell us the wall's rough height and length, what's above it, and your address or parcel number. See our concrete flatwork services.

Sources

• Nine Mile Falls, Washington (Wikipedia, straddles Spokane and Stevens counties)
• Suncrest, Washington (Wikipedia, Stevens County CDP)
• Spokane County BP-25, Permit Exemptions
• City of Spokane / Spokane County Joint Policy BUILD-07, Official Frost Depth
• Stevens County Building Code Ordinance 02-1984 (frost depth)
• Stevens County Building FAQs
• Stevens County Shoreline Master Program
• WAC 51-51-003, Washington's adoption of the International Residential Code
• ICC Significant Changes, IRC Section R404.4 Retaining Walls
• NOAA NCEI, 1991-2020 Monthly Normals, Spokane International Airport