The present invention is a non-woven fiber mat suitable for reinforcing resilient sheet floor coverings, such as vinyl floor coverings. The woven fiber mat is in the form of a sheet of reinforcement fibers (14) which at least includes semi-coiled fibers (18) and slightly curved fibers (20). It is desirable for most, if not all, of the reinforcement fibers (14) to be made from glass. However, it may also be desirable for the reinforcement fibers (14) to include glass fibers and synthetic fibers. It may even be possible for the reinforcement fibers (14) to include only non-glass fibers. At least one polymeric binder is used for bonding together the reinforcement fibers (14) so as to make the fiber mat a suitable substrate for reinforcing resilient sheet floor coverings, such as an interlayer for vinyl floor coverings. By using a non-woven fiber mat containing reinforcement fibers (14) that are not completely straight and capable of interlocking with one another, a resilient sheet floor covering made with such a mat can exhibit improved planar compressibility.