Commercial Kitchen Extract Lining in 1 Day – VentilFlex-25


  • download the brochure
  • application area: commercial
  • use type: extraction of cooking gases from kitchen
  • project scope: line brick extraction shaft to prevent grease build-up
  • added value: 25-year guarantee on liner, minimal downtime, easily fitted due to flexible material

kitchen extract lining

The Queen Alexandra Hospital in Cosham, Portsmouth, serves the city of Portsmouth and the surrounding area, with over 1,400 beds and has a busy commercial kitchen supplying restaurants and residents. Increasing reports of fumes from the greased-up extraction ducts (brick shafts) have been a concern.

men load equipment on site

Certified VentilFlex25 installer Toast Ltd was selected to resolve the issue set out in the tender design for the upgrade of Portsmouth Hospital’s kitchen extract riser. A survey of the riser and plantroom was carried out to determine the most suitable solution. The existing riser, which runs along the full height of the building, is divided into 4 sections creating 4 separate ventilation systems.


Statement of work

One of the remaining three shafts had been in use without a kitchen extract liner for the extraction of kitchen gases. This was a concern as during kitchen extraction grease build-up can create a fire hazard. The greasy condensate can also breach the brick walls, which can result in unpleasant odours within the building.

To minimise downtime, it was decided to build the new kitchen extract flue system within the shaft section which had been made redundant. Due to the restricted size of the available space within the shaft, access was an issue and conventional ducting solutions had to be ruled out. VentilFlex-25 kitchen extract lining system was the chosen alternative lining method, with its jointless design, excellent heat resistance and fire rating, and crucially, an installation method that only required access at the top and the bottom of the riser.

metal circle inside ductA stainless-steel rig was installed into the walls of the riser to support the 1-meter diameter, 25-meter-long liner. This was necessary as the liner would not be supported by the brick walls of the riser.

The VentilFlex-25 liner is supplied as a single-length, jointless and flexible piece of material. It is a composite, heat-resistant-resin impregnated fibre design, which needs to be pressurised and heated during installation to gain its final shape and strength. Following correct installation by a Kompozit’All UK certified installer, the liner comes with a 25-year manufacturer warranty.

kitchen extraction shaft linerThe installation of the liner was completed within the day from insertion to the finished product. Following the installation, the existing kitchen exhaust system was re-connected into the shaft with the new VentilFlex-25 liner inside.

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