Concrete blocks (masonry units) are defined as solid, cellular or hollow.

Concrete blocks are manufactured to various work face dimensions in an extensive range of widths, offering a wide choice of load-bearing capacity and level of insulation. Manufacturer’s work size dimensions should be indicated as length, width and height, in that order, to BS EN 771–3: 2011 and BS 6073–2: 2008.

The standard work face size, which coordinates to three courses of metric brickwork allowing for 10 mm mortar joints, is 440 X 215 mm ,

but the other sizes in below Table are marketed for aesthetic and constructional reasons.

For example, narrow bands of a different color may be used as visual features within fairfaced blockwork, and foundation wall blocks are normally laid flat. The use of thin-joint masonry offers speedier construction, especially when using large format blocks , which are approximately equivalent in size to two standard units. However, blocks heavier than 20 kg should not be lifted by a single person, as this can potentially lead to injury. Within the 20 kg limit are 100 mm-wide aircrete blocks with face dimensions 610 X 375 mm for speedy construction using the thin-joint system.