Contents
- An introduction to foundation piling
- When should foundation piling be used?
- What are the different types of foundation piles?
- What is foundation piling made of?
- How do you install foundation piling?
- How do you choose the right foundation piling method?
- How do you prepare a site for foundation piling?
- What are the benefits and drawbacks of foundation piling installations?
An introduction to our foundation piling guide
If a structure is being built on unstable soil or on foundations that need further reinforcement, foundation piling is the best way to ensure it is stable, durable, and long lasting.
Foundation piling uses long, vertical structures (called piles), which are then drilled or driven into the ground until they reach a stable, load-bearing layer of sub-soil or rock. Piles aim to effectively distribute the load of a structure for enhanced safety and stability.
There are two main categories of piled foundations. These include replacement piles (also known as bored piles), which involve excavating the soil to install the piles, and displacement piles (also known as drive piles), which are driven directly into the ground.
Depending on the type of pile used, they can be made from:
- Steel: Prized for stellar strength and durability.
- Concrete: Cheaper than steel but offers more versatility in shape and size.
- Timber: Less common now due to more secure materials, but still an affordable option.
When should foundation piling be used?
Foundation piling can be used to reinforce the structural integrity of extensions, new builds, and various other projects where the existing ground conditions are less than desirable.
Many construction projects use foundation piling for structural support when dealing with poor soil, extremely heavy structure installations, and environmental challenges.
For poor soil conditions
Soil in one area can be completely different to that in another. So when building a structure on weak soil, foundation piling is essential for distributing the load to deeper and more stable layers beneath the ground.
Some of the most difficult soils to build on include:
- Peat (spongy with a high water content)
- Clay (unstable and prone to movement
- Sand and silt (erosion-prone and loose)
- Limestone (unstable and shatter-prone)
Structures built on reclaimed land, industrial sites, or swamps and marshlands may also run into similar issues.
For extra heavy loads
Heavier structures demand foundations with reliable load-bearing capabilities. Foundation piling has become a reliable and efficient way to ensure the stability of heavy load-bearing structures like high-rises, bridges, warehouses, factories, and more.
For environmentally challenged areas
Foundation piling can reinforce stability in water-logged and flood-prone areas. Building on ground with these characteristics can be risky, as excess water can result in a loss of bearing capacity, erosion, and uplift forces. Foundation piling offers the same support for areas prone to ground movement, like those built over tunnels.
What are the different types of foundation piles?
We’ve looked at the two main categories of piles (replacement and displacement), but what about specific types? It’s important not to get these confused with piling methods, which we will go into later.
There are three main types of piles:
- End-bearing piles: Designed to bypass any weak soil and instead transfer the load of structure directly to a stronger layer of subsoil or rock beneath the ground. They come in different sub-types, including steel H-piles, concrete piles, and steel pipe piles.
- Friction piles: Work by generating friction between the pile surface and the surrounding soil, distributing the structure of a load. They can be made from timber (an outdated option nowadays), concrete, and steel. Friction piles aren’t ideal if the soil conditions are at high risk of changing over time, as this can affect load capacity.
- Sheet piles: Thin, vertical, interlocking panels made from steel, vinyl, or concrete. They’re a little different from the previous two types as they don’t support structural loads but act as walls to prevent soil movement and water flooding.
What is foundation piling made of?
Choosing the best material for foundation piling depends on the area’s soil condition, how heavy the structure to be installed is, and any environmental factors to be considered.
The construction company or piling contractors for the project will conduct a site survey to assess these factors, which will help them choose the best-suited piling material for the job.
| Piling material | Strengths | Weaknesses | Applications |
| Timber | Budget-friendly, lightweight, easy to install, sustainable, and durable in water. | Limited load capacity and subject to rot or insect infestations. | Marine temporary structures, small buildings, and piers. |
| Steel | Durable, impressively load-bearing, and reusable. | High price-point and slightly prone to corrosion unless coated. | High-rise buildings, bridges, and industrial structures. |
| Concrete | Durable, strong, fire-resistant, and water-resistant. | Difficult to install and transport, heavy, has a high price point, and requires curing time. | Bridges, structures in flood-prone areas, and structures requiring deep foundations. |
How do you install foundation piling?
We’ve looked at the two piling categories, the three piling types, and their sub-types, but how are foundation piles installed? Some of the most common types of piling methods include:
- Driven piling: Pre-fabricated piles hammered into the ground using an impact hammer.
- Bored piling: A drilled hole, reinforced and filled with concrete.
- Screw piling: Steel piles with helical blades twisted into the ground.
- Sheet piling: Interlocking sheets driven into the ground to create a protective wall.
- Mini piling: Small diameter piles drilled into the ground for foundation repairs and tight workspaces.
- Grundomat piling: Small-diameter steel or concrete piles installed using compressed air-driven hammers.
For more details about each step in the process, take a look at Our Beginner’s Guide to Different Types of Piling Methods.
How do you choose the right foundation piling method?
When choosing the best foundation piling method for any construction project, it’s important to consider a few key factors that can influence your final decision.
| Piling method | Ideal soil type | Load capacity | Vibration and noise | Cost |
| Driven | Dense | High | High | £££ |
| Bored | Soft | Very high | Low | £££ |
| Screw | Soft | Medium | Very low | £ |
| Sheet | Loose | Low | Medium | ££ |
| Mini | Weak | High | Very low | ££/£££ |
| Grundomat | Soft | Medium | Very low | £ |
How do you prepare a site for foundation piling?
Before determining the best foundation piling type for a construction project, it’s important to assess, prime, and prep the work site. This is an essential part of the process as it ensures that the foundations will be as stable and secure as possible while also enhancing the operational efficiency of the piling.
Step 1: Conduct a site assessment
- Collect soil samples to determine soil type, moisture content, and load capacity.
- Testing methods: Standard Penetration Test (SPT), Cone Penetration Test (CPT), and soil borehole and laboratory testing.
- Carry out a topographical survey to map out the area’s contours, elevations, and obstructions.
- Conduct a groundwater level and drainage assessment to determine whether extra reinforcement is needed.
Conducting a soil assessment will tell you what pile type and depth you need and any risks to look out for. It will also ensure that the chosen piling type and methods suit the site’s conditions and characteristics.
Step 2: Prepare the ground
- Remove any existing trees, bushes, rocks, and debris from the area.
- Remove any existing foundations, pipes, or wiring underground.
- Level the surface, ensuring sufficient water drainage mechanisms are in place.
Preparing the ground will prevent any equipment from getting damaged or any delays in the piling process due to unknown obstructions.
Step 3: Excavate and compact
- Remove any weak or loose topsoil.
- Compact the remaining soil using a vibrating roller or plate compactor.
- Add gravel or crushed stone and compact if the soil is still too loose.
- (Optional) Pre-drill a guide hole if the ground is too dense or rocky.
- (Optional) Add a geotextile, geogrid, or sand/gravel/concrete fill if the ground is soft or waterlogged.
Excavating and compacting the ground will prevent collapsed foundations while ensuring the installation goes smoothly and the piles remain secure.
What are the benefits and drawbacks of foundation piling installations?
Foundation piling is a popular construction technique due to its many benefits, applications, and variations. However, there are a few potential downsides to consider for certain applications and projects.
The potential drawbacks of foundation piling
- It can be expensive, but the process can introduce long-term savings thanks to reduced maintenance and reliable structural durability.
- It causes high levels of noise and vibration, but there are alternative foundation piling methods that are designed to keep disturbance to a minimum, like mini-piling, bored piling, and screw piling.
- It can be time-consuming and complex, but the process is worth it for security, stability, and longevity. There are also methods like screw and driven piling, which allow for faster installations.
- It isn’t very environmentally friendly — not true! Bored piling and screw piling methods minimise soil disruption and have a smaller environmental footprint.
The benefits of foundation piling
- It can support heavy loads: Foundation piling can effectively re-distribute structure weight to stable, reliable ground.
- It is suitable for a variety of soil types: From soft and loose to watery and dense, foundation piling methods can be tailored to different soil types.
- It can reduce the risk of structural failure: Foundation piling can reduce the likelihood of foundational failure, tilting, and cracking.
- It can keep foundations secure in high-water areas: Foundation piling (especially sheet piling) can provide flood protection and enhance soil retention for a more stable structure.
- It can be used on sites with tight spaces and restricted access: Foundation piling methods — micro-piling and grundomat piling especially — are designed to be used in confined areas.
WL Piling: Your trusted piling contractors in the North West
If you’ve enjoyed our beginner’s guide to foundation piling, don’t hesitate to check out our other blogs for more information and advice.
At WL Piling, our piling specialists are proud to have over 50 years of combined experience. This experience has helped us deliver reliable piling services across the North West with a focus on positive customer service, high-quality piling installations, and the best equipment and materials on offer.
If we can assist you with your construction project, don’t hesitate to contact us today to discuss your needs.
