FLI Structures - Screw Piles Foundations

Steel Grillages


As well as screw pile foundations, FLI Structures designs and supplies specialised grillage foundations. These can support structures in all market areas.


Installation of Grillage

How do grillage foundations work?

Depending on the size and weight of the structure being supported, a traditional foundation of this type (sometimes called a floating foundation) is a large box-like structure, not unlike the mesh cages used to reinforce concrete structures. Unlike the latter, where the reinforcement is ultimately surrounded by concrete, a steel grillage is a rigid construction that's placed at sufficient depth below ground that the weight of soil removed to place it equals the weight of the supported structure. Increasingly, for structures such as road signs or railway gantries, steel grillages consist of one or more steel beams (an interface) mounted on underlying helical piles.


Installed Grillage

Grillages and helical screw piles

An interface grillage is often positioned atop several helical screw piles. Typically, there will be between four and eight depending on the application and the weight of the structure. These carry tension and compression loads and are particularly resistant to overturning moments. The visible structure, whether a gantry support or a road sign, is then attached. As well as securely anchoring the structure, using screw piles and interface grillages offers contractors considerable time savings. This is particularly due to the avoidance of using poured concrete and the reduced disruption of road and rail traffic flows that results.

Grillage on Highways

For more information, please contact us.