Sustainable development implies the multiple goals of achieving progress in society, the environment and the economy. In this pursuit, valorization or “up-cycling” of industrial and domestic wastes must clearly play a role. This is particularly important with polymers, plastics and elastomers, which over the years have become necessary to modern life but harmful to our environment through the waste produced. This paper is based on this philosophy and presents new work to re-use waste plastic and rubber materials that are otherwise dumped in landfills at an increasing cost both to the economy and the environment. The targeted waste derives from scrapped tyres, cars (which incorporate many plastic parts such as bumpers, dash board, paneling and seats), carpets (rubber backing and polymer piles) and similar granular-fibrous mixed residues, perceived as low value difficult to recycle waste. In our research, these wastes are processed into new added-value acoustic and thermal insulating products to meet the growing public expectation for reduced energy costs and a quieter environment. The basis of the new process developed is about tailoring a porous structure using plastic, rubber and fiber waste so that the final material possesses particular acoustic and or thermal properties. The process, performed cold in a shallow single screw extruder, compounds the waste with a chemical foaming binder in a judicious manner that controls the foam reaction, subsequent pore network (open or close) and the final product foam structure.