Sheet material used on flooring as a base for carpet. It is essential to use underlay for satisfactory carpeting, as it acts as a. shock absorber between the carpet and the floor. However, some carpets now have their own foam-backing bonded to them, which makes underlay unnecessary.
A good-quality underlay will always give a better finish to the carpet than a poorer quality one. Paper felt is an inexpensive underlay, but is suitable only for rooms such as bedrooms, which are not in constant use. Underfelt is a more popular underlay; it consists of felt layers bonded together to give a cushion effect. Rubber underlays made of foam or natural rubber are also popular. They should not be used, however, where there is underfloor heating.