Cellvent HX

Cellvent HX combines the benefits of the Cellcore HX range with Ventform to alleviate the effects of ground heave whilst also providing an excellent gas venting medium. It is designed for use under suitably reinforced ground floor slabs where subsidence is not expected.


  • Provides combined ground heave protection and gas venting capabilities in a single product
  • Range of thicknesses and grades to suit most project requirements
  • Light, robust and easy to install 2400mm x 1200mm panels
  • Unaffected by both UV light and water.

Cellvent HX is available in a range of specifications to accommodate the ground conditions of any particular project and can be used in conjunction with Cordek gas membranes, vent outlets and venting accessories to form a complete gas protection system.


Designed for use beneath reinforced concrete floor slabs to provide a combined ground heave protection and passive gas venting system.


The tables below provide guidance for determining the most appropriate depth and grade of Cellvent HX panel, based upon the characteristics of the expansive soil type and the proposed thickness of the reinforced concrete slab:

The depths available are:

Soil Plasticity Index NHBC Shrinkage Category Maximum Heave Potential (mm) Cellvent HX Product Depth (mm)  Equivalent Cellcore HXS Depth (mm)
10-20 Low
50 135
Medium 100 205 160
High 150 270 225

The grade of Cellvent HX is determined by the depth of the concrete slab:

Cellvent HX Grade     Maximum Safe Load (inc. 1.5kN/m2 live load) Fail Load (kN/m2)
Maximum Depth of concrete (mm)
7/10 7    10  220
9/13 9    13 300
13/18 13    18 460
18/24 18    24 660

Based on the above tables, the Cellvent HX specification for a 250mm thick concrete slab on top of medium shrinkability clay would be: Cellvent 205 HX 9/13.

Cellvent HX is supplied with an equivalent ventilation capacity to the Ventform 80 range which includes a 40mm void depth. If a greater venting capacity is required, please contact the Cordek Technical Team on 01403 799600 for further guidance.


Data Sheets

Product Issue Date Version Size Download
Cellvent HX Data Sheet 01/2021 4 329.7 KB

Standard Details

Product Issue Date Version Size Download
Cellvent HX Standard Detail 01/2018 1 50.5 KB

MSDS Data Sheets

Product Issue Date Version Size Download
Expanded Polystyrene MSDS 06/2017 5 137.3 KB

Certification, Approval & Guidance

Product Issue Date Version Size Download
BBA Certificate - Cellcore HX 09/2021 3 526.4 KB


Product Issue Date Version Size Download
Construction Solutions 01/2020 2 6.6 MB
Ground Heave Solutions 08/2017 1 1,014.7 KB
VOC & Ground Gas Protection 07/2019 4 4.0 MB

Installation Guides

Product Issue Date Version Size Download
Cellvent HX Installation Guide 12/2018 1 239.2 KB

NBS Clauses

Our NBS Clauses are hosted on the external website - view NBS Clauses

BIM Library

Please select the BIM file in the format you require.

Name IFC Size IFC Download Revit Size Revit Download
Cellvent HX 28.3 KB 932.0 KB

Not sure which product meets your requirements?

Contact a Technical Advisor now

Find your nearest Technical Advisor

For international enquiries please contact Peter Blanchard

For enquiries in the Manchester or Liverpool
areas please contact James Provan

Or contact Cordek Head Office