This part of ISO 8144 specifies the properties and acceptance tolerantes for bonded man-made mineral wool thermal insulating mats (batts and rolls). The mats specified in this part of ISO 8144 are only intended to be used for horizontal applications with unrestricted Ventilation, where any excess of thickness recovery of the insulation mat will not restritt the essential Ventilation space [see annex E and ISO/TR 9774:1990 (figure 1, Sketch 23, right-hand drawing) for examples of the application]. Insulation in ventilated roof spaces requires that the Ventilation to the air space is guaranteed. Depending upon the location of the insulation, the product thickness may interfere with this requirement. The mineral wool mats which are specified in ISO 8144-1 :1995 are primarily intended for use in applications where any excess of thickness has to be limited. This part of ISO 8144 provides limiting values for most of the properties. These Iimiting values are for specification purposes only; design values may be derived from these by taking into account the environmental factors affecting the thermal performante of the product, the influence of the product properties on installation, and the effect of workmanship on the thermal Performance. For converting declared R-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.