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Void Formers

Void spaces (gaps) are designed to provide an intended buffer zone or clearance between expansive soils and a concrete foundation in order that heave can occur without imposing detrimental uplift pressures to the foundation. Such voids are filled with expanded polystyrene compressible-fill material and/or specialised honeycomb materials. While the expanded polystyrene would compress and uncompress taking away the soil heave stress from the foundation and the foundation slab, the proprietary honeycomb system is a collapsible system, which would leave space under the foundation slab, after the honeycomb is bio-degraded.  The honeycomb system is used usually under foundation slabs. Void formers under the grade beams will typically be required if the uplift forces from the soil are greater than the dead load plus sustained live load of the foundation and superstructure.

Advantages

  • A foundation slab with void space below allows expansive soils to swell into the void space, thereby reducing the risk of foundation heave.
  • Foundation slabs that are elevated above the surrounding grade are less affected by surface water prior to concrete placement.
  • Allows to build on sites with inadequately compacted, untested soil or other soil conditions that may not be suitable to support the construction of grade-supported foundations.
Disadvantages

  • Creates a path for water to migrate below the slab, particularly when the bottom of the void space is near or below adjacent grade. 
  • Usually increases cost of the design and construction.
  • Concrete may enter the honeycomb form or the expanded polystyrene during placement, if any stakes are driven through them, or any space left between them.
Expanded polystyrene (EPS) is recognized and accepted as the lightweight fill alternative to soil and is increasingly used in commercial and residential applications. Given EPS' low weight, strength, and ease of use, it is used to solve construction challenges in following applications:
  • Lightweight structural void fill,
  • Lateral load reduction on structures,
  • Lateral and dead load reductions over buried utilities,
  • Soft soil remediation,
  • Slope stabilization
Benefits of using compressible EPS fill materials as an alternative to traditional soil fill.
  • Can be used where the use of larger mechanical equipment may not be feasible.
  • Project construction time is reduced.
  • Can be installed during any type of weather or site conditions.
  • Project construction time is reduced as it is lightweight.
  • Concrete, soil or any other material can be placed directly on EPS, eliminating formwork.

CHOOSE MANUFACTURERS or scroll down to see products (show)

Brand: Kay-Metzeler Model and Size: 1200x2400 - 2.88m2
Delivery Time: 2 - 3 working days
50mm Claylite is a low density expanded polystyrene compressible-fill material which can be used to reduce the pressure exerted on reinforced concrete ground beams or on the vertical face of concrete foundations, caused by the expansions of clay soils (clay heave) during the life of the structure. C..
Guide Price: £20.46
£24.55 inc VAT
Brand: Jablite Model and Size: 2400x1200mm - 2.88m2
Delivery Time: 1-3 working days
50mm Claymaster is an EPS compressible-fill material that helps prevent potential foundation problems caused by moisture movement in soils with a high proportion of mineral particles below 0.002mm (clay heave). It can be used as permanent shuttering for cast in-situ reinforced concrete, relieving pr..
Guide Price: £15.30
£18.36 inc VAT
50mm Heaveguard - Expanded Polystyrene Board Used Against Ground Heave - 2400mm x 1200mm
Guide Price
Brand: Cordek Model and Size: 2400x1200mm - 2.88m2
Delivery Time: 2 - 3 working days
50mm Heaveguard is a compressible low density Expanded Polystyrene (EPS) board, used when foundations need to be protected against ground heave and against lateral heave. Heaveguard is used to prevent potential problems in foundations due to moisture movement in soils, such as clay heave, reducing p..
Brand: Dufaylite Model and Size: 600mm - 36mm diameter
Delivery Time: 2 - 3 working days
600mm Dufaylite Void Pack Pipe for Clayboard Void Former System is a 36mm diameter plastic pipe, supplied with a rubber flange for seamless jointing and a cap to stop concrete blocking the tube. It is used to introduce water into the Clayboard core after the concrete has been poured and set. On..
Guide Price: £14.40
£17.28 inc VAT
Brand: Dufaylite Model and Size: 1000x2440mm - 80.52m2
Delivery Time: 5 - 7 days
60mm Dufaylite Commercial Clayboard Void Former is a lightweight board available in four different thicknesses, and especially applicable to large scale, commercial projects. It is made from extremely environmentally friendly components, lowering the carbon footprint of the building, but also provid..
Guide Price: £2,516.15
£3,019.38 inc VAT
Brand: Dufaylite Model and Size: 1000x2440mm - 80.52m2
Delivery Time: 5 - 7 days
60mm Dufaylite Residential Clayboard Void Former is a specially designed board consisting of a lightweight, eco-friendly and biodegradable core covered with polypropylene facings. The product is designed to prevent the common problem of expansion and shrinkage of clay soil when it is ..
Guide Price: £2,143.46
£2,572.15 inc VAT
85mm Heaveguard Pile Collar 450mm x 450mm
Guide Price
Brand: Cordek Model and Size: 85mm x 450mm x 450mm
Delivery Time: 2 - 3 working days
85mm x 450mm x 450mm Heaveguard Pile Collar is a compressible low density Expanded Polystyrene (EPS), used to support pile heads against lateral ground heave. It is a part of the Cordek Cellcore ground heave system. The pile collar will fit securely around the pile head to produce a square edg..
Brand: Cordek Model and Size: Filcor EPS
Delivery Time: 3 - 5 days
Filcor EPS is an Expanded Polystyrene lightweight structural fill alternative to more traditional fill materials or as a lightweight void former in structural concrete. The standard (and  the maximum) sheet or block size is 2400mm long x 1200mm wide x required thickness. The thicknesses fr..
Brand: Dufaylite Model and Size: 1000x2440mm - 2.44m2
Delivery Time: 2 - 3 working days
60mm Dufaylite Residential Clayboard Void Former is a specially designed board consisting of a lightweight, eco-friendly and biodegradable core covered with polypropylene facings. The product is designed to prevent the common problem of expansion and shrinkage of clay soil when it is ..
Guide Price: £62.33
£74.80 inc VAT
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