Steel Cased Piling vs Open Bore Piling: Which Is Right for Your Project?

Steel cased piling and open bore piling are two of the most commonly specified piling methods used in modern foundation construction. Both systems are designed to transfer structural loads into suitable bearing strata beneath the ground, providing stable foundations where traditional foundation methods may be unsuitable.

While both techniques achieve the same overall objective, they are designed for different ground conditions, project requirements and construction environments. Understanding the differences between steel cased piling and open bore piling can help property owners, developers and contractors make more informed decisions when planning a project.

Understanding the Role of Piling in Foundation Design

Piling is typically used when ground conditions prevent traditional strip foundations from providing adequate support. Poor bearing capacity, made ground, clay soils, groundwater and restricted site conditions can all influence foundation design and lead structural engineers to specify a piling solution.

The primary purpose of piling is to transfer structural loads through weaker soils and into stronger load-bearing strata beneath the surface. Selecting the correct piling method is critical to achieving long-term structural performance and cost-effective construction.

Two of the most widely used solutions are steel cased piling and open bore piling, each offering distinct advantages depending on the conditions encountered on site.

What Is Steel Cased Piling?

Steel cased piling involves driving steel tubes or casings into the ground using specialist piling equipment. Once the required depth has been achieved, reinforcement and concrete are installed to create a strong and durable foundation element.

The steel casing provides support during installation and allows piles to be constructed successfully in ground conditions that may otherwise present challenges for bored piling methods.

Steel cased piling is commonly used on sites with variable ground conditions, loose soils, groundwater issues or where enhanced load-bearing performance is required.

What Is Open Bore Piling?

Open bore piling is a bored piling technique that uses a rotating auger to excavate the pile bore before reinforcement and concrete are installed. Unlike steel cased piling, the bore remains unsupported during excavation, meaning the surrounding soil must be capable of remaining stable throughout the installation process.

This method is typically used where cohesive soils allow the bore to remain open without collapse. Open bore piling is widely regarded as an efficient and cost-effective foundation solution when ground conditions are favourable.

The technique is commonly specified for residential developments, commercial projects and sites where stable clay soils or similar ground conditions are present.

The Main Differences Between Steel Cased and Open Bore Piling

Although both systems create deep foundations, the way they are installed differs significantly.

Steel cased piling relies on a permanent or temporary steel casing that supports the pile during installation. This makes it suitable for more challenging ground conditions and environments where bore stability could become an issue.

Open bore piling, by contrast, depends on the surrounding soil remaining stable during excavation. Where this can be achieved, installation is often quicker and more economical because temporary casing is not required.

The choice between the two methods is rarely based on preference alone. Instead, it is determined by site investigations, soil conditions, groundwater levels and structural requirements.

Ground Conditions and Site Suitability

Ground conditions are often the deciding factor when selecting a piling method.

Where sites contain made ground, loose soils, groundwater or highly variable strata, steel cased piling may provide the most reliable solution. The steel casing helps maintain pile integrity throughout installation and reduces the risks associated with unstable ground.

Open bore piling is generally more suitable where cohesive soils allow the bore to remain stable. Clay-rich sites often provide favourable conditions for open bore installation, making it an attractive option where site investigations confirm suitable ground characteristics.

This is why ground investigations and geotechnical surveys are such an important part of the foundation design process.

Which Piling Method Is More Cost Effective?

Many clients naturally want to know which piling solution is the most economical. The answer depends entirely on the conditions present at the site.

Open bore piling can often provide cost advantages where suitable ground conditions exist because the installation process is relatively straightforward and does not require steel casing throughout the pile construction process.

However, where unstable ground conditions are encountered, attempting to use open bore piling may create complications that ultimately increase project costs.

In these situations, steel cased piling may represent the more practical and cost-effective solution despite the additional materials involved. The most economical foundation system is usually the one that is best suited to the site rather than the one with the lowest initial installation cost.

How Structural Engineers Choose the Right Solution

Structural engineers do not select piling methods at random. Their recommendations are based on site investigations, soil reports, groundwater assessments and structural calculations.

The design process considers factors including bearing capacity, anticipated loading, access restrictions, environmental conditions and construction constraints. Once this information has been reviewed, engineers can determine which piling solution is most appropriate.

This ensures the chosen foundation system provides the required structural performance while remaining practical and economical to construct.

Choosing the Right Piling Solution for Your Project

Both steel cased piling and open bore piling are proven foundation solutions capable of delivering excellent long-term performance when used in the correct conditions. Neither method is inherently better than the other; the key is selecting the solution that matches the ground conditions and structural requirements of the project.

By carrying out thorough site investigations and working with experienced piling specialists, developers, contractors and property owners can ensure the most suitable foundation system is selected from the outset. This not only improves construction efficiency but also helps create stable foundations designed to support structures safely for many years to come.