Setting out
Brickwork CO− / CO / CO+
- where
- coordinating size (mm)
- full stretcher modules
- brick length (mm)
- perpend joint (mm)
Explain this equation
This gives coordinating sizes for brickwork, so that piers, panels and openings are dimensioned to whole bricks and avoid cutting.
n is the number of full stretcher modules, l is the brick length and j is the perpend joint, all in mm. One module is a brick plus one joint, l + j. CO is n of those modules. CO− has one joint fewer, which is the size of a pier or panel with free ends. CO+ has one joint more, which is the size of an opening between two pieces of brickwork.
A run of n bricks always contains n bricks and either n − 1, n or n + 1 joints, depending on what is at the ends. Subtracting or adding one joint to CO gives the other two cases.
With 215 mm bricks and 10 mm joints a module is 225 mm. Four modules give a 900 mm CO, an 890 mm pier and a 910 mm opening.
Watch out: this covers full bricks only. It does not deal with corners, half-bat bonds or specials.
Calculate three boundary conditions for a number of full stretcher modules.
Enter your values to see the result.
Good to know
Use the boundary condition shown on the drawing. This full-unit calculator does not automatically resolve corners, half-unit bonds or specials.
Sources
- BDA dimensions
Estimates are not design approval or British Standards compliance checks. Structural arch, retaining-wall, wind, foundation, lintel and masonry-capacity design are not performed. Use the project engineer’s specification.