Brick Tolerances
You can download an explanation of BS EN 771-1 brick height tolerances here.
Most brick slip systems, with the exception of Barracuda, rely for their satisfactory performance, on the engagement of cut or purpose made brick slips into a rail system. This means that the height of the bricks becomes critical to their safe retention by the system.
Almost all bricks used in the UK are declared, by their manufacturer, to comply with the maximum permissible deviations in brick height, stipulated within BS EN 771-1. These permissible deviations are very large. The majority of brick slip systems, with the exception of Barracuda, are only capable of accommodating a small part of this permissible deviation range. It is very important that the specifier of a brick slip system thoroughly understands the deviation in brick slip height that might occur on their project and the real capability of any brick slip system to accommodate them.