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Build a retaining wall

Step 1 - Lay the foundation

Identify where you want the retaining wall and dig a trench 500mm deep x 500mm wide x length of proposed retaining wall.
Box up the trench with boards constructed from timber which is 25mm thick, and as wide, and deep as the trench. Hold the timber frame in place with 50mm square stakes that are level with the timber frame when knocked in. Check the level of the work area with a spirit level. Allow for any desired slope and check the diagonals. Lay construction mesh on the floor of the boxed trench.

Step 2 - Lay the concrete

Calculate how much concrete you will require (one 40kg bag of Cemix Multicrete will produce concrete equivalent to 500mm x 500mm x 76.8mm) use the Quantity Calculator on this website to calculate other quantities. Empty contents of Cemix Multicrete into a wheelbarrow, mechanical mixer or onto a smooth non-porous surface. Add water gradually, mixing thoroughly until a smooth mix is achieved. Under ideal conditions one 40kg bag of Cemix Multicrete would require 4 litres of water.

Fill half the depth of the boxed trench with a firm mix of Cemix Multcrete and lay a second layer of construction mesh on top. Work the concrete so that it is compact and air voids are removed. Fill the remaining depth of the boxed trench with a firm mix of Cemix Multicrete, level the top and allow to cure for three days.

Step 3 - Lay the bricks

Use CEMIX Cemortar DIY to build up the double brick wall. Calculate how much mortar you will require (one 20kg bag of Cemix Drimix Mortar Mix is enough to lay 20-25 standard bricks, or 15-20 concrete blocks). Empty contents of Cemortar DIY into a wheelbarrow, mechanical mixer, or onto a smooth non-porous surface. Add water gradually, mixing thoroughly until a smooth mix is achieved. Under ideal conditions a 20kg bag of Cemix Cemortar DIY would require 3 litres of water.

Dampen clay bricks before laying them, however concrete blocks should be laid relatively dry. Trowel a layer of mortar 15-20mm thick between the concrete foundation and the first row of bricks. Leave small gaps in the mortar of the first layer of bricks for drainage. Trowel mortar vertically between bricks so that it is 10-15mm thick. On the layers where the bricks extend past the length of the wall turn the bricks on the side so they fit. Continuously check the wall with a spirit level as you progress. Pointing bricks is easier after the mortar has initially set.

Step 4 - Prepare the drainage and finish the wall

Behind the wall, just above the base foundation place a 15cm deep layer of gravel. Lay a Slot Drain on the gravel with both ends protruding beyond the width of the wall. Back fill the rear of the wall with soil.