Filler sheets are designed for cutting into filler pads for use where water resistant material is required and where resistance to dimensional change under compression, rather than resiliency, is important. The fillers must function over a service life of 20 years under adverse (hot, cold, high humidity) environments without degrading to the point where they are unusable. Under this specification, plastic materials, paper or fiberboard, combinations of both or any other material capable of meeting all the requirements specified herein are acceptable. Material that has historically been submitted under this specification and that has been found to meet all requirements has been paperboard or kraft paper laminated with an outer plastic waterproof layer.