Screw Piles vs Mini Piling
Both screw piles and mini piling can provide effective foundation solutions where traditional strip foundations are unsuitable. However, they are not two directly equivalent systems.
Screw piling is a specific foundation method using steel shafts fitted with helical plates. Mini piling is a broader term covering a range of piling systems installed using compact or restricted-access equipment.
The correct solution will depend on the ground conditions, structural loads, access constraints and practical requirements of the individual project.
What Are Screw Piles?
Screw piles, also known as helical piles, are steel foundation elements comprising a central shaft and one or more helical plates.
They are installed by mechanically rotating the pile into the ground using handheld equipment or a machine-mounted hydraulic drive system.
The pile is advanced until it reaches either the specified design length or the required target torque. The correct pile diameter, depth and helix arrangement depend on the ground conditions and structural loading requirements.
Screw piling can offer several practical benefits, including:
- Rapid installation
- Minimal excavation and spoil
- Low noise and minimal vibration
- No concrete required for the pile installation itself
- Suitability for some restricted-access projects
- The ability to remove piles used for temporary structures
Learn more in our guide: What Is Screw Piling and Where Is It Used?
Further technical information is available on our Screw Piles service page.
What Is Mini Piling?
Mini piling refers to a range of piling techniques generally installed using smaller, more compact equipment.
It is commonly considered where access is restricted, headroom is limited or ground conditions make conventional foundations impractical.
Mini piling can include several different installation methods, such as:
- Driven piles
- Bored piles
- Drilled piles
- Sectional auger systems
- Screw piles
This means that screw piles can sometimes fall within the wider description of mini piling, depending on the pile size and installation equipment used.
Mini piling can be used across both residential and commercial projects.
Learn more on our Mini Piling service page.
For an overview of the systems available, read Different Types of Mini Piling Methods Explained.
Screw Piles vs Mini Piling: Key Differences
| Consideration | Screw Piles | Mini Piling |
|---|---|---|
| Definition | A specific steel pile system fitted with helical plates. | A broad term covering several compact piling methods. |
| Installation | Mechanically rotated into the ground. | May be driven, bored, drilled, augered or screwed. |
| Materials | Steel shaft and helical plates. | Depends on the selected piling method. |
| Excavation | Generally produces minimal excavation and spoil. | Varies according to the pile type and installation method. |
| Noise and vibration | Low noise and minimal vibration. | Varies depending on whether the pile is driven, bored or drilled. |
| Restricted access | Can be installed using handheld or compact equipment where suitable. | Frequently selected for restricted-access or low-headroom sites. |
| Selection | Based on ground conditions, installation torque, pile capacity and structural loads. | Based on the ground conditions, structural requirements, access and selected mini-piling method. |
How Are the Installation Methods Different?
Screw Pile Installation
Screw piles are installed by applying rotational force to the steel shaft. The helical plates allow the pile to advance through the ground as it is rotated.
Installation is monitored against either a specified target torque or design length. The equipment used must be capable of applying the torque required by the pile design.
Our guide to how deep screw piles go explains why the required depth varies between sites.
Mini Pile Installation
There is no single mini-piling installation process because the term covers several methods.
A mini pile may be driven, bored, drilled, augered or screwed into the ground. The system selected will depend on the ground conditions, loading requirements, access and environmental constraints.
For example, a project with restricted headroom may require a sectional system, while a different site may be better suited to a driven or drilled pile.
How Do Ground Conditions Affect the Choice?
Ground conditions are often one of the deciding factors when selecting a foundation method.
The available ground investigation information can help determine:
- The soil types beneath the site
- The depth of suitable bearing material
- Whether obstructions or variable strata are present
- The required pile depth and specification
- Which installation methods may be practical
Screw piles rely on the selected pile specification and installation torque achieving the required capacity.
Where the ground is unsuitable for screw pile installation, another mini-piling method may provide a more appropriate solution.
Read more about why site investigation is important for pile design.
Which Method Is Better for Restricted Access?
Both screw piles and mini-piling systems can be suitable for restricted-access projects.
Typical examples include:
- House extensions
- Back garden developments
- Existing buildings
- Urban construction sites
- Sites with narrow access routes
- Projects with overhead restrictions or limited headroom
Screw piles may be installed using handheld or compact machine-mounted equipment, depending on the pile specification and required torque.
Other mini-piling methods may also use compact rigs designed specifically for confined areas or restricted headroom.
The correct choice will depend on more than the physical size of the equipment. The ground conditions, structural capacity and installation requirements must also be considered.
Learn more in our guide to restricted access piling.
Screw Piles vs Mini Piling for House Extensions
Both options may be considered for house extensions where conventional foundations are unsuitable.
Mini piling is commonly used for:
- Rear and side extensions
- New residential structures
- Projects with difficult or variable ground conditions
- Sites where access for larger piling rigs is limited
Read more in our guide: When Do You Need Mini Piling for a House Extension?
Screw piles may also be suitable where the ground conditions, structural loads and access allow them to be installed correctly.
Further information is available in our guide to screw piles for house extensions.
Do Both Systems Require Ground Beams?
The connection between the piles and the supported structure depends on the foundation design.
Screw piles can sometimes be connected directly to steel or timber structures using an engineered connection. In these circumstances, conventional pile caps or reinforced concrete ground beams may not be required.
Other screw-piling and mini-piling projects may require:
- Reinforced concrete ground beams
- Pile caps
- Floor slabs
- Steel connection frames
- Other project-specific foundation details
The required connection must be designed around the loads, pile positions and proposed structure.
How Do the Costs Compare?
There is no universal answer to whether screw piles or another mini-piling method will cost less.
The cost of either option will depend on factors including:
- Ground conditions
- The number of piles required
- Pile depth and specification
- Structural loads
- Site access
- Installation equipment
- The required foundation connection
- Additional groundworks
The lowest initial pile price does not necessarily represent the best overall foundation solution. Installation time, excavation, spoil removal, ground beams and associated works must also be considered.
Further information is available in:
Advantages of Screw Piles
Where the system is suitable, potential advantages can include:
- Rapid installation
- Minimal excavation and spoil
- Low noise and minimal vibration
- No concrete required for the pile installation itself
- Immediate connection to some supported structures
- Suitability for temporary and removable installations
- Compact installation equipment
For a fuller review, read our guide to the advantages and disadvantages of screw piling.
When Might Another Mini-Piling Method Be More Suitable?
An alternative mini-piling method may be more appropriate where:
- The ground conditions are unsuitable for screw piles
- The required torque cannot be achieved using equipment that can access the site
- Obstructions or variable strata influence installation
- A driven, bored or drilled system better suits the structural requirements
- Different pile diameters or capacities are required
- The project has specific headroom, noise or vibration constraints
The method should always be selected through engineering assessment rather than choosing between screw piles and mini piling based on cost or installation speed alone.
Which Is the Right Choice?
There is no universal answer to whether screw piles or another mini-piling system is the better solution.
The correct foundation method will depend on:
- Ground investigation findings
- Structural load requirements
- Site access and working space
- Headroom restrictions
- Noise and vibration considerations
- The required foundation connection
- Programme and project objectives
In some cases, screw piles may provide the most efficient and practical solution. On other sites, a different mini-piling system may provide a more suitable foundation design.
Speak to Our Piling Team
At Dawson Foundation Engineering, every project is assessed individually to determine the most appropriate foundation solution.
We provide free site visits and no-obligation quotations for residential and commercial projects throughout the UK.
To discuss your project, call 0333 224 5196 or contact our team.