محصولات سقف شیبدار
Materials: Avoid specifying unproven products. Specify that the manufacturer shall have produced the specified materials for a minimum of five years.
When referencing a product standard (such as ASTM), it may be appropriate in some instances to just list the standard. But many ASTM standards have grades, types or both within the standard. In these cases, the type and grade need to be specified. Also, additional information sometimes needs to be specified, such as product thickness. Products covered by some ASTM standards have a substantial range in physical properties. In some cases, it is appropriate to specify a physical property value(s) that is different from that specified in the standard so that a higher quality is obtained. However, this approach should not be used as a method to exclude essentially equal products just because one product has a slightly different value.
Protection of the completed work: If other construction work will occur over the new roof, or if other construction trades will be on the new roof, specify appropriate protection measures.