Course gauge & height

This gives the course gauge, the height of a set number of courses, and the level at the top of them. Use it for gauge rods, sill and lintel heights, or finished levels.

h is the height of one unit and j_b is one bed joint, both in mm. Their sum, g, is the gauge. n is the number of courses and H their total height in mm. L₀ is the starting datum level and L_top the level reached, both in metres.

Every course adds one unit and one bed, so the height is n × g. The datum is in metres but H is in millimetres, so H is divided by 1000 before adding it to L₀.

Standard bricks at 65 mm with 10 mm beds give a 75 mm gauge, so 4 courses rise 300 mm and 32 courses rise 2400 mm. From a 0.000 datum that puts the top at 2.400 m.

Watch out: this counts one bed under every course, including the first, and no bed on top. Check that matches how the drawing sets its datum.