A wall built from two components: heavy king piles, usually box or H sections, installed at intervals to carry bending and vertical load, and lighter intermediate sheet piles spanning between them to retain the soil. Concentrating steel where the bending demand is highest allows a wall to be far deeper and more heavily loaded than plain sheet piling of equivalent total weight.

Because interlock continuity has to be maintained through a change of direction, and any discontinuity is both a structural weakness and a leakage path. Standard piles allow only a limited angle of deviation, so anything beyond that requires bent corner piles, junction sections or welded connectors. Corners are where sheet pile walls most commonly leak and where alignment errors accumulate during driving.

A waling is a horizontal beam running along the face of the wall that collects load from many piles and delivers it to discrete support points. Tie rods then carry that load back to anchors in the ground behind the wall, or props carry it across an excavation. Together they convert a cantilever wall into a supported one, which reduces bending and required embedment substantially.

It caps the head of the wall, distributing load between piles, providing a level and accurate finished line to build from, and giving a fixing point for railings, fenders, road restraint or the structure above. On permanent works it also protects the pile heads and improves appearance. It is usually reinforced concrete cast onto the trimmed pile heads.

With interlock sealants, applied to the interlocks before driving, which swell on contact with water or which are bituminous and deform to fill the gap. Welding interlocks on the exposed face after installation is an alternative for critical sections. Neither achieves absolute water tightness, so designs normally combine sealing with drainage or pumping rather than relying on the wall alone.

Driving caps and helmets that sit between the hammer and the pile head to spread the blow and prevent local damage, packing to absorb energy, and rock shoes or reinforced points at the toe where hard driving or rock is expected. Threading and pitching frames hold piles in alignment while they are engaged and driven, which is what keeps a wall straight and prevents declutching.

Once the retained height exceeds what passive resistance below excavation level can economically support, which depends on soil strength and is quite modest in most conditions. Beyond that point, embedment depth for a cantilever rises rapidly and anchoring becomes far cheaper. The decision is made in design, and the anchor or prop level is chosen to minimise bending in the wall.