This Saudi standard specifies the definition, classification and characteristics, sampling, inspection , testing and market release requirements of the lightweight masonry units which incorporate an interior or exterior insulation layer (hollow or non-hollow) or made of foamed concrete (which possesses cellular pores) or made of concrete manufactured from lightweight aggregates such as pozzolanic aggregates for manufacturing volcanic concrete units or other type of lightweight aggregates such as ( blast-furnace slag, clay, diatomite, fly ash, shale, slate, pumice ..etc.) or aggregates from schist, quartz, feldspar, or mica powder or made of lightweight concrete manufactured using polystyrene and incorporating a concrete layer on its exterior, or made of a mixture of polystyrene granules with foam concrete (lightweight aerated concrete) intended to be used on the non-loadbearing masonry parts of other structures for building and civil engineering. In this standard, the expression “masonry unit” refers to lightweight masonry units with insulation layer.