The advancement of chemically impregnated membranes has made this method od pre-construction protection safe, affordable and veru effective. The products range from sealant to dampcourse membranes and use active ingredients such as bifenthrin and deltamethrin impregnated into the fibres, sheeting, or geotextile to act as a permanent and effective barrier to termites. They are odourless and are expected to last at least 50 years abd require almost no ongoing maintenance.