The invention relates to a deformable mat comprising at least one lap consisting of at least one reinforcing material and at least one thermoplastic material. According to the invention, the aforementioned materials take the form of continuous and/or cut yarns and said yarns are connected to one another such that the mat has an elongation at rupture in all directions of at least 50 % and, preferably, between 100 and 150 %. The invention also relates to a method of producing the deformable mat, consisting in: forming a lap of the aforementioned yarns, treating the lap under determined conditions such as to enable the yarns to be joined to one another, and collecting the mat thus obtained. The invention further relates to the use of the mat for the production of composite parts by means of vacuum or compression moulding.