Engineering bricks come in two strength classes: Class A and Class B - Class A being the stronger of the two. You would use engineering bricks in construction for their strength and ability to withstand frost and wet conditions - they are not used for aesthetic purposes. Their main uses would be for building foundations, retaining walls, DPCs, and underground tunnels such as sewers. You’ll find red and blue engineering bricks in our range, as well as both Class A and B bricks.