SOLAS Bricklaying cheat sheet

Bricklaying

• Standard UK brick dimensions are 215 mm long x 102.5 mm wide x 65 mm high; with a 10 mm joint the coordinating size is 225 x 112.5 x 75 mm, giving 60 bricks per square metre of half-brick wall.

• Mortar mix by volume for general brickwork: 1 part cement : 1/4 part lime : 3 parts sand (strong) or 1:1:6 (general purpose); below DPC and in exposed locations use stronger mixes and sulphate-resisting cement where ground sulphates are present.

• Bond rules: a half-brick wall needs a minimum 1/4-brick lap; a one-brick wall uses stretchers and headers to tie the two leaves. English bond alternates full stretcher and header courses; Flemish bond alternates stretcher and header in every course.

• Course height check: 4 courses of 75 mm coordinating height = 300 mm; a gauge rod marked at 75 mm intervals is used to keep bed joints at 10 mm and courses level.

• Setting out: establish a square corner with the 3-4-5 method (or Pythagoras) before building; diagonals of a rectangular building must be equal to confirm squareness.

• Movement joints in brickwork are typically placed at 10-12 m centres for clay brickwork and closer (about 6 m) for concrete brickwork, and at changes of height or material; compressible filler plus a sealant is used.

• Wall ties in a cavity wall are spaced at maximum 900 mm horizontally and 450 mm vertically, with additional ties around openings; ties must slope slightly downwards towards the outer leaf to shed water.

• DPC must be at least 150 mm above finished external ground level; mortar droppings must be cleaned off the DPC and cavity board kept in place to prevent bridging.

• Brick strength classes (e.g. 10, 20, 30 N/mm2) and frost resistance (F0, F1, F2) must suit exposure; bricks below DPC or in severe exposure need F2 frost resistance and a suitable mortar.