What is a pile foundation?
A pile foundation is a foundation method in which long piles are driven or bored into the ground until they reach a deep, load-bearing soil layer. This method is used when the upper soil layers are too weak to support a building — think of peat and clay areas in the west of the Netherlands.
How does it work?
The piles act as vertical columns that transport the weight of the building through the weak upper layers to a firm sand layer deep in the ground. On top of the piles, a concrete beam or slab is cast on which the walls are built.
The difference from a shallow foundation is fundamental:
- Shallow foundation — Rests directly on a shallow load-bearing layer
- Pile foundation — Passes through weak layers to a deep load-bearing layer
When is a pile foundation needed?
| Situation | Pile foundation needed? |
|---|---|
| Sandy soil (east/south NL) | No — shallow foundation is sufficient |
| Clay on sand | Usually not — depends on layer thickness |
| Thick peat layer (west NL) | Yes |
| Reclaimed land | Yes |
| Heavy structure (multiple storeys) | Often yes |
Types of piles
Driven piles (precast concrete)
The traditional method: prefabricated concrete piles driven into the ground with a pile driver. Reliable, but causes vibrations and noise.
Screw piles
Steel piles with a helical blade that are screwed into the ground. Less vibration, suitable for construction near existing buildings.
Bored piles
A hole is drilled and filled on-site with concrete and reinforcement. Vibration-free, but more expensive.
Timber piles
The oldest method. Still present under many historic buildings in Amsterdam and other cities. No longer used for new construction.
Pile foundation for DIY projects
For a garden building, shed or canopy, a pile foundation is usually not needed and not feasible to do yourself. The alternatives:
- Pier foundation — Individual concrete piers at strategic points. Suitable for lightweight structures.
- Ground screws — A DIY-friendly alternative: steel screws that you drive into the ground with a machine or by hand. They do not reach the depth of driven piles, but are sufficient for lightweight structures on moderately weak soil.
> Important: If you want to place a heavier structure (masonry garage, large shed) on weak soil, always have a soil investigation report (CPT) carried out. This tells you at what depth the load-bearing layer is and whether you need piles.
Cost indication
| Type | Cost per pile (indication) |
|---|---|
| Driven pile (precast concrete) | €40-80 per linear metre |
| Screw pile | €150-300 per pile |
| Bored pile | €80-150 per linear metre |
| Ground screw (DIY) | €30-60 per screw |
Including pile driver and labour, a pile foundation for a garage easily costs €3,000-8,000, depending on the number of piles and the depth.
Related terms
- Shallow foundation
- Pier
- Strip foundation
- Concrete slab (floor slab)
- Reinforcement