Provoid Gas Venting System consists of a 25mm geo – composite ‘void former’ that can be laid under the entire floor slab or, in strips at pre-determined centres, to suit the gas regime on site. Provoid 25 has been extensively tested as part of the DETR ‘Partners in Technology’ Report. When installed with the Provoid range of air inlets and outlets (please contact us for site – specific details), it can dilute harmful gases down to the required design concentrations for your site.