ACS Distance Education UK
Measure the site and mark out the corners of the trench. Put wooden pegs into the ground at each corner. Make up some timber profiles 1 m beyond the outer edge of the foundation trench. This will keep the string line out of the way when attached. Next, attach string lines to each profile to indicate the width of the wall and trench.
Dig out the required area:
Determine levels with a string line and level. On sloping ground, steps need to be created in the footing so that the wall maintains an even height.
Install timber form work to support the concrete while it sets.
Place steel rods or mesh fabric in the trench to give the concrete rigidity and strength. The mesh is supported by plastic “chairs”, concrete blocks or steel supports and these should be laid in place before the concrete is poured. Usually, one support per linear metre is sufficient.
Pour the concrete - 1 part cement: 2 parts sand: 4 parts gravel. Spread the concrete within the form work and level it off to 100 mm below ground level. Smooth it off with a wooden or steel float.
Cover the footing with plastic sheeting and leave it to cure for 7 days.
Stretcher bond is a commonly used pattern for single brick walls. This involves staggering the vertical joints by half a brick for each layer. For double brick walls, a header course every three to five courses gives added strength (e.g. English garden wall bond). On smaller walls a header course laid as the top course (soldier course or capping) gives a similar effect.
All courses and vertical joints should be separated by 10 mm of mortar. The mortar can be made from 1 part cement: 6 parts sand: 1 part lime. This mix is more workable and makes the mortar soft and pliable. However, it will only last a maximum of one and half hours (depending on how hot and dry the weather is), after which time it loses its elasticity and should be thrown out.
Depending how many people are working on the job, the mortar can be mixed by hand in a wheelbarrow or on the ground on a sheet of board, or mechanically mixed in a cement mixer. After mixing, it is transferred onto a mortar board to make it easier to pick up with a brick trowel.
Learn to work with brick, stone and concrete