Types of Sheet Piles Explained – Z, U and Tubular

What Are Sheet Piles?

Sheet piles are interlocking steel sections used to create retaining walls that resist earth or water pressure. They’re widely used for:

• Excavation and basement support

• Flood defences and riverbank stabilisation

• Ports, harbours, and marine structures

• Temporary or permanent retaining works

Their strength, watertightness, and speed of installation make them one of the most efficient ground support systems in construction. Learn more about the process of sheet piling in our recent blog. 

Z-Type Sheet Piles

Z-piles are the most common profile in use today. Their distinctive Z shape positions the interlocks on the outer edges, giving them a wide effective section and excellent bending strength.

Advantages:

• High strength-to-weight ratio

• Efficient load transfer and minimal deflection

• Ideal for deeper or permanent retaining walls

• Suitable for vibro, impact, or silent press installation

Common Uses:

• Deep basements and cut-and-cover tunnels

• Marine and flood defence walls

• Heavy civil engineering and infrastructure works

Z vs U Piles:
Z-piles deliver higher bending resistance, making them the preferred choice for deeper excavations or marine environments where strength and durability are critical.

U-Type Sheet Piles

U-piles remain a trusted choice, particularly for smaller or temporary works. Their symmetrical U shape makes them easy to align, drive and extract.

Advantages:

• Balanced design for simple handling

• Effective for circular or cellular structures

• Cost-efficient for temporary retaining walls

• Good reuse potential

Common Uses:

• Cofferdams and temporary earth retention

• Riverbank stabilisation

• Bridge abutments and shallow excavations

U-piles are versatile and economical but generally offer lower bending capacity than Z-sections. They’re often reused multiple times on short-term or sequential projects.

Tubular Steel Piles

Tubular piles, or circular hollow sections, are large-diameter steel tubes driven vertically into the ground. While not interlocking like sheet piles, they play a major role in marine and heavy civil engineering, either as standalone foundations or as part of a combi-wall system with infill sheet piles.

Advantages:

• Extremely high axial and bending strength

• Customisable diameter and wall thickness

• Excellent durability in marine and offshore conditions

• Works as both bearing and retaining element

Common Uses:

• Quay walls, jetties, and bridge foundations

• Heavy waterfront and port infrastructure

• Combined retaining and load-bearing systems

When combined with Z-piles as infill, tubular piles form a combi-wall — offering the stiffness of a driven column with the continuity of a sheet wall.

Hot-Rolled vs Cold-Formed Sheet Piles

The way sheet piles are manufactured directly impacts their performance.

For permanent or marine environments, hot-rolled Z or U piles remain the industry standard thanks to their superior interlock integrity and corrosion resistance.

Which Sheet Pile Is Best for Deep Excavations?

For deep or high-load excavations, Z-piles typically provide the best balance between strength and cost. Where additional stiffness or axial load capacity is needed — such as in quay walls or bridge abutments — tubular piles or combi-wall systems are preferred.

In contrast, U-piles are better suited to shallower or temporary works where quick installation and reuse are priorities.

Factors to Consider When Selecting a Sheet Pile Type

Selecting the right section involves more than strength alone. Key factors include:

A thorough ground investigation and early consultation with an experienced piling contractor help avoid design changes later in the programme.

Common Pitfalls

• Selecting piles based on price or stock rather than design requirements

• Ignoring soil resistance and driveability data

• Using cold-formed piles in marine or permanent applications

• Over-specifying heavy sections that add unnecessary cost

• Neglecting to match pile type to available installation method

Which Sheet Pile Type Is Most Cost-Effective?

For long-term or marine projects, hot-rolled Z-piles often deliver the best lifecycle value thanks to strength and reusability.
For shorter, temporary works, U-piles or lightweight cold-formed sections can be more economical.
The true cost efficiency lies in matching the pile type to both the ground conditions and the intended lifespan of the wall.

Conclusion

Every project has its own demands — and each sheet pile type brings specific strengths.

• Z-piles: strong, versatile, and ideal for deep, permanent walls

• U-piles: practical, reusable, and perfect for temporary works

• Tubular piles: unmatched for marine and high-load applications

The best results come from early design input, accurate ground investigation, and a contractor who can deliver all systems in-house.