Abstract: The present invention relates to a substrate based on nonwoven sheet for a flat article.The substrate 11, with good dimensional stability in all the conditions of production, of subsequent treatments and of use, comprising at least one nonwoven sheet 8 based on chemical textile material in the form of continuous fibres or filaments is characterized in that the said sheet comprises high-modulus reinforcing threads 3 arranged parallel to each other in its lengthwise direction.Glass threads are preferably employed as reinforcing threads. The reinforcing threads are combined with the nonwoven sheet by chemical bonding or heat-bonding and/or needling.Use of the support as a sealing membrane reinforcement, primary or secondary substrate for tuft carpeting, reinforcement for floor covering tiling, substrate for laying, substrate for flock, and the like.