When dimensioning brickwork, and positioning and sizing openings, it is preferable to use increments based on the length of a brick, then no cut bricks will be required and brickwork around openings will be symmetrical and the bond regular. However, this is not always possible and these notes deal with accommodating opening widths that are not of whole brick increments of standard metric bricks, particularly openings for 'Co-ordinated Size Components', a standard range of door and window units of metric modular co-ordinated sizes (typically required for health service buildings designed in compliance with Health Technical Memorandum no 55 ).
Figure1: It is often possible to base overall dimensions on whole brick increments, but not always to size and position openings to suit. Half-brick increments should be the second preference. This will result in either broken bond (alternate courses of half and two cut bricks above and below the centre of the opening) or reverse bond.
Figure 2: With reverse bond the jambs of an opening are not symmetrical - not generally obvious except where the jamb bricks are a contrasting colour.
Figure 3: When openings cannot be of brick dimensions, for example when using some 'Co-ordinated Size Components', dimension brickwork between them using whole brick increments, accepting that the overall length of the wall will not be a brick dimension and broken bond will occur at the centre of the openings.
Figure 4: If there are overriding reasons for making the overall length of the wall a brick dimension, for example where a large expanse of multi-storey brickwork has a few openings at one level, the openings should be positioned with their centre lines on brick dimensions. There will be no broken bond above or below the openings, but cut bricks will be necessary in the brickwork between some openings depending on their size and spacing.
Malcolm Barnett is Education Architect at the BDA. Contact him for details of CPD and university lecture services