Ground gas and geomembrane specialists

Gas protection ventilation

Voidformers / vent layers for gas protection ventilation

PAGeoTechnical has developed an extensive range of gas protection ventilation products that include voidformers and vent components. When installed as part of a designed gas venting system, they will safely disperse harmful gases to atmosphere.

Under BS8485:2015 it is recommended that all gas protection designs should include provision for some form of sub-floor ventilation. Depending on the site risk this may be a simple pressure relief pathway or demonstrable ventilation with good or very good performance.

PAG offer advice and design appropriate for the gas risk identified including demonstration by calculation for ventilation design performance. All part of our ground gas solutions.

passive ground gas control illustration
Geocomposite installation

Ground gas protection ventilation components

PAGeoTechnical  has developed an extensive range of ventilation components that when installed as part of a designed gas venting system will safely disperse harmful gases to atmosphere. All PAG passive gas venting components are supplied with venting calculations to prove their efficiency in line with BS 8485.

The range includes T pipes, bends and couplings, slotted pipes, voidformer outlets, air bricks, periscope vents and many more.

PAG Standard Venting Components

Datasheets and brochures



Venting descriptions

Details of venting components available from PAG.

Vent-to-vent layer detail

Typical venting component detail.


Rectangular vent.


Round gully vent.

V40 vent box

Standard vent box.

PAG Standard Venting Components

List of PAG venting components.

PAG 25 Ventlayer

Geocomposite venting layer suitable for use in all ground gas applications.

PAG 6 Fully Wrapped

Fully wrapped geocomopsite drain for pressure relief designs underneath buildings.

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