The finishing touches. At natural structures we use a new method of laying our Oak floors using a Envoy Floor Underlay. After completing the Green Oak Structure one of the next steps is to lay the floor which more often than not is either Oak or limestone both of which are normally laid over a pre-installed under-floor heating system. The envoy system is a 4mm thick high density foam with one side coated in an adhesive that is designed to stick when the Oak floor boards come into contact with the adhesive. This enable,s us to create a tight fitting free floating Oak floor.