"Claustres" - general characteristics "Claustres" are decorative elements designed for the construction of openwork walls called claustra. Traditional motifs include curves, squares, rectangles, honeycombs, "grand provençals" spiralling into a series of circles, and more. A number of contemporary ornamental shapes are also manufactured. At present, there are no standards regulating their application. Sound-absorbent walls The clay masonry industry has developed a number of acoustic screens. They consist of perforated or openwork sound-absorbent clay units (usually including fibrous materials). Some units can be covered with tiles. Technical Assessments have been issued by the CSTB (Centre Scientifique et Technique du Bâtiment) for some clay acoustic screens. The properties of these products must conform to the following French standards which are also valid European standards: NF EN 1793-1 "Test method for determining the acoustic performance. Part 1: intrinsic characteristics of sound absorption" NF EN 1793-2 "Test method for determining the acoustic performance. Part 2: intrinsic characteristics of airborne sound insulation". Their performance is indexed according to a scale. The standards for the non-acoustic characteristics of screens designed to reduce traffic noise are laid down in: NF EN 1794-1 "Non-acoustic performance. Part 1: mechanical performance and stability requirements" NF EN 1794-2 "Non-acoustic performance. Part 2: general safety and environmental requirements". Inspection is carried out in conformity with French standard NF S 31-089 "Test code for the determination of acoustical characteristics of sound barriers installed in a free field" (currently under revision). These standards are accompanied by technical recommendations drawn up by the CERTU.