A construction element for forming an expansion joint, wherein the construction element acts as a physical and chemical barrier against the penetration of insects, in particular termites, into a structure, the construction element comprising a closed cell polymeric foam containing at least one insecticide substantially distributed throughout the polymeric foam； wherein on at least one outer surface of the construction element there is a water resistant adhesive attached thereto and a removable cover releasably attached to the adhesive whereby the removable cover is adapted to be removed upon application of the casting element.
