The present invention relates to a combined liquid foam stop and insulator for a tank assembly including a fibrous material strip and a nonflammable insulating skirt connected to the fibrous material strip. In an alternative embodiment the invention is the liquid foam stop in the form of a fibrous material strip and in the absence of the nonflammable insulating skirt. Further, the invention includes a gas water heater incorporating the liquid foam stop or the combined liquid foam stop and insulator of the present invention.