Concrete Retaining Walls in Steilacoom, WA

Retaining walls in Steilacoom: what to know

Under the state rule, the measured height starts at the underside of the footing and ends at the top edge of the wall. At four feet or less, with nothing surcharging its back and no impounded liquid of the classes the state names, the wall is not subject to a building permit. Steilacoom’s code leaves retaining walls and rockeries out of the structure definition in SMC 18.08.880, and its building code does not amend the wall exemption. In a street setback, SMC 18.20.080 limits fence and wall height together, so a wall with a fence on top is measured with the fence.

Walls near the water fall under the shoreline chapter, SMC 16.08. Its normal protective bulkhead exemption for a single-family home, in SMC 16.08.320(A)(3), covers a bulkhead that guards against erosion near the ordinary high water mark without creating land.

Permits and rules in Steilacoom

Before a wall is quoted, we check its height from the footing’s underside upward, log every load behind it, and confirm it against the state rule and the street-setback limit in SMC 18.20.080. A shoreline or steep-slope wall gets a separate look, and we confirm with the town whether a geotechnical report applies before drawings are finalized. Where a wall sits in the buffer that SMC 16.16.770(A)(1) sets at the larger of the slope height or 50 feet, we ask the town how that buffer applies to the lot.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Read the wall height from the footing bottom upward
Log every bank, building, or vehicle that loads the wall
Confirm which wall rules the town applies to this parcel
Set the drain outlet clear of the road and the slope

For the full process, see our Retaining Walls page.

Building in the cold months? See our guide to winter concrete pours.

Our retaining walls work, serving Steilacoom

Examples of our work. We build retaining walls in Steilacoom and the cities around it. See all of our work

Questions from Steilacoom homeowners

Does Steilacoom’s building code change the four-foot wall exemption?

No. Chapter 15.04 adopts the 2021 International Building Code and Residential Code and amends the driveway and deck exemption in SMC 15.04.060(a)(1), but it lists no change for retaining walls. Under the state rule, a wall at four feet tall or less is exempt unless a surcharge loads it or it impounds a Class I, II, or III-A liquid.

What does SMC 18.20.080 set for a Steilacoom fence on top of a wall?

The combined height of fence, wall, or berm in a street setback cannot exceed the setback’s fence maximum, and half of any fence or wall section above 42 inches must be see-through. We confirm those figures for your lot before drawings go out.

When does a Steilacoom wall need a landslide report?

A project in a landslide hazard area needs a geotechnical report under SMC 16.16.750. SMC 16.16.710(B) sets that area by slope, including a slope of 40 percent or more with 10 feet or more of relief, or a slope over 15 percent with permeable soil over an impermeable layer and seepage. We measure the slope on your lot against that definition before design.