Do I Need an Engineer for a Retaining Wall in Missouri?

Missouri cities — Kansas City, St. Louis, Springfield, Columbia — generally require an engineer-sealed plan set for retaining walls at or above the local height threshold, and the PE seal is the standard requirement for the structural sheets. The seal must show the engineer's name, Missouri PE number, and date, with the engineer in responsible charge. Low garden walls in good soils can sometimes be permitted from prescriptive block details, but any wall carrying a surcharge — driveway, parking, structure, or slope above — is treated as engineered work in Missouri, regardless of height. Owner-builders don't escape the requirement: the building department asks for the seal regardless of who drew the plans, and the engineer must design the wall for Ozark karst, bootheel seismic, and Kansas City expansive clay.

The engineer selects the wall system for karst-probed walls in the Ozarks, seismic-detailed walls in the bootheel, swell-designed walls in Kansas City — the engineer matches the system to the hazard, and designs the drainage as karst-safe dispersed discharge — the engineer keeps concentrated water off soluble rock across the Ozarks. Sliding, overturning, and bearing go on the sealed calculation set — plus a global stability check proving the whole slope stands with the wall on it, which is the check that governs on sites with Ozark karst, bootheel seismic, and Kansas City expansive clay. Bring a topographic survey or site plan showing existing and proposed grades, the wall's height and length, and photos of the slope. Missouri walls face caves, quakes, and swelling clay — the engineer investigates for voids, designs for shaking, and details for swell.

Use this checklist before engaging an engineer for your retaining wall: • Engineer of record holds an active Missouri PE license, verifiable on the state roster • Wall height, surcharge loads, and soil profile established by borings or test pits • Wall type selected for Ozark karst, bootheel seismic, and Kansas City expansive clay — cantilever, segmental, tieback, or gravity, not a default • Drainage detailed: perforated drain, weep holes, free-draining backfill, outlet daylighted • Global and compound stability checked for Ozark karst, bootheel seismic, and Kansas City expansive clay, not just the wall section • Surcharge from driveways, structures, and slopes above included in the design • Frost protection and base key detailed for Ozark karst, bootheel seismic, and Kansas City expansive clay • Engineer confirms they'll respond to plan-check corrections on sealed sheets