Sigma GP Titan Flex – Gas and Hydrocarbon Barrier is a multi-layer, polyethylene membrane. Sigma GP Titan Flex is specifically designed and manufactured to perform as a Methane, Carbon Dioxide, Radon, Ground Gas, VOC, air & Moisture and Hydrocarbon protection system. Sigma GP Titan complies with the latest codes of practice as published by BRE, CIRIA (C748) and BSI (BS 8485:2015). Suitable for use as Ground Gas/Hydrocarbon protection for NHBC GREEN, AMBER 1, AMBER 2 and RED site characterisations.