Engineering bricks are fired to a high temperature of between 1200 and 1300 degrees centigrade until they are almost molten. The high firing temperature prevents the formation of air pockets or pores in the bricks and they are, therefore, dense, strong and non-porous, which makes them ideal for use in retaining walls, below DPC level, below ground, inspection chambers, copings to the top of walls, DPCs (when in solid form), and so on. ‘Engineerings’ generally weigh between 3.5 and 4.5kg each. Although they can be of ‘facing’ variety, most are smooth-faced, which means that they might be defined simultaneously as ‘common’, albeit of much better quality.
Fig. 33 Engineering bricks (perforated).