A thermal barrier liner is provided to maintain a beverage within a container at a desired temperature. The thermal barrier liner is installed so as to make intimate contact with the internal surface of the container. According to a method of the invention, the liner is pre-made and mechanically inserted in the container prior to securing the top of the container to the sidewall. A closed cell structure is incorporated in the thermal barrier material. The closed cell structure causes the thermal barrier material to be gas permeable such that voids in the closed cell structure equilibrate with ambient pressure conditions. The voids change size based on changes in ambient pressure conditions as compared to pressure conditions in the thermal barrier material.