This part of ISO 8144 specifies the properties and acceptable tolerantes for bonded man-made mineral wool thermal insulating mats (batts and rolls). The mats specified in this part of ISO 8144 are for use within ventilated roof spaces of buildings where the essential Ventilation of the roof space may be restricted if the thickness recovery of the insulation is excessive. [See annex E and ISO/TR 9774:1990 (figure 1, Sketches 1 and 5) for typical locations.] They may be supplied flat, folded or in the form of a roll. The properties to be declared by the manufacturer at the time of delivery are specified, as are some test methods for the determination of these properties. Essentially, mats do not Change their properties and are dimensionally stable for the temperature and humidity conditions within a ventilated roof. This part of ISO 8144 provides limiting values for most of the properties. These limiting values are for specification purposes only; design values may be derived from these by taking into account the environmental factors affecting the thermal Performance of the product, the influence of the product properties on installation, and the effect of workmanship on the thermal Performance. For converting declared R- or L-values to design values, see, for example, ISO 10456. Mats may be supplied with a factory-applied facing, but facings are not covered by this part of ISO 8144. In general, mats are not designed to support any applied load. For this reason, only the mechanical properties required for adequate handling during application are specified. The sampling and conformity control procedures described in annex D, and the certification procedure described in annex F, are recommendations only.