Heave Stopper

Protecting structures against clay heave and ground movement

Clay Heave & Ground Recovery

Groundbeams and slabs can be cracked by the pressure that ground movement causes when concrete foundations are built on shrinkable soils such as clay and expansive shale soils, or when development is on reclaimed land or subject to ground recovery caused by deep excavations.

The structural damage caused by clay is well understood by engineers and designers all over the world. Here in the UK the problem is particularly acute in the South East although climate change is having its effect on soils in other parts of the country.

Rehydration of desiccated and compacted shrinkable soils are the main reasons for clay heave

Heave Stopper - Forming a true void

Unlike other solutions Heave Stopper creates a complete void beneath the foundation to offer maximum protection from ground movement.

Heave Stopper is a board constructed from a cardboard honeycomb core set between water resistant facings.

When dry, the boards have a compressive strength that can support concrete and steel up to 1 meter thick without deflection or creep compression. Once the concrete is cured and self supporting, Heave Stopper’s job is done. Water is now introduced to the core, and in this process Heave Stopper yields to ground heave without transmitting pressure to the structure. Eventually, the board will naturally disappear to leave a permanent 100% void with no residual density to pass on heave stresses.

This can allow engineers to design thinner slabs and beams using less concrete and reinforcement.

Heave Stopper can also be used to create a void to protect structures from vibration.

More benefits of Heave Stopper

The technical and cost benefits of Heave Stopper make it
the complete solution for void creation.

BBA Approved

Meets the technical requirements of the NHBC

Suitable for beams & slabs

Cost effective with additional savings on excavation depths, blinding layer and no requirement to blind over boards

The slimmest method of void creation means less excavation

A perfect solution for contaminated land and brownfield sites

Ideal for sites with restricted access

Lowest possible forces transmitted to the structure

Heave Stopper - Why it works best


Light and easy to use, Heave Stopper can be installed at a rate of 50m2 per hour or more by one operative.


Heave Stopper can be installed either side up, is easily cut with simple hand tools and the joints do not need to be taped together.


The close cell structure means that Heave Stopper can be trimmed tightly around pile heads and service ducts without losing the integrity of the panel.

Heave Stopper is delivered on pallets to allow mechanical offload and stacking during storage. Each pallet is protected with a polythene cover. Pallets are manufactured from the same material as Heave Stopper boards and are therefore easily recycled. In addition, there is a range of ancillary items available to ensure total satisfaction for every installation.

These include:

  • Void Pipe
  • Polythene sheeting
  • Lay flat tubing
  • Waterproof tape
  • Reinforcement spacers

Environmental benefits

The environmental and sustainability
credentials of Heave Stopper are second to none.

The core and facings are manufactured from 100% recycled materials

Materials are FSC approved

Efficiency of void creation means less excavation, muck away, vehicle movements and landfill

Easily recycled in normal waste streams. No need for collections from site and processing at specialist facilities

Naturally biodegradable

Design thinner slabs and beams using less concrete and reinforcement

Specifiers Guide

Heave Stopper is straight forward to specify. All Heave Stopper boards will satisfy the requirements for beams, slabs and concrete thickness up to 1 meter. For concrete pours over 1 meter a special grade of Heave Stopper is available.

Simply select the correct thickness to accommodate the heave potential of the ground based on site investigation and soil analysis results. Further guidance on predicted ground movements in shrinkable soils is given in the NHBC Standards 2013, Chapter 4.2

The thickness of Heave Stopper should be equal to the required void plus 10mm see table below:

Heave Stopper has a compressive strength of 30kn/m2.

When dry, it is designed to have sufficient strength to support wet concrete and steel up to 1 meter thick. When the core is wetted it will yield to the pressure of ground movement with less than 3kn/m2 of transmitted force to the structure above.

The board’s mechanical properties have been independently tested at the BRE Innovation Park. Tests show that the initial saturation procedure leaves just 10mm of material in the void zone.

Ultimately a 100% clear void is created which is in excess of the specified requirements and with zero kn/m2 of transmitted force.

Heave Stopper can also be used horizontally and vertically to create avoid to protect structures from vibration.

Board Size

Heave Stopper is supplied in boards 2400mm long by 1200mm wide, by the specified thickness.