Today’s Checkatrade expert is Nick Underwood, owner of 1st Choice Improvements.
Many people choose to build low brick walls in their gardens, sometimes to surround ponds or seating areas, sometimes just for decoration. For the DIY competent this is a relatively straight-forward process and can be highly rewarding. But if it goes wrong mistakes can be costly to rectify, so follow the steps below.
• Ready-mixed mortar
• Ready-mixed concrete
• Hammer and bolster chisel
• Plastic sheet
• Sheet of plywood
• Brick trowel
• Spirit level
• Plumb line
• Garden lines and pegs
• Timber boards
1. Laying the foundations
All walls need a firm foundation. Mark the position of the wall using garden lines and pegs to ensure it is square and dig the foundation trench along its length. For walls up to 1 metre it will need to be at least 35 centimetres deep. If the soil is soft or unstable it may need to be deeper. Check the trench is level and its sides are vertical using a spirit level.
Mix the concrete according to the manufacturer’s instructions, pour it into the trench and chop through it with the shovel to dispel air and work it in. This concrete layer is known as the ‘footing’ and for a low wall should be around 150 millimetres thick. When this is finished cover with a plastic sheet and leave to harden for a few days.
2. Mortar preparation
First, at each end of the trench put timber profile boards and stretch guidelines between them to mark the width of the wall. This will keep it square while you are laying bricks. Next mix the mortar on the plywood sheet to protect the ground. Use a spade with a chopping motion to fold the mix together and eliminate concrete streaks. The mortar should be a consistent colour and stiff enough to hold its shape.
3. Laying the first row
First, lay a thin layer of mortar (about 1 cemtimetre thick) along the footings. Apply mortar to the first brick with a ‘buttering’ motion and place it on the footings with the brick’s hollow (known as the ‘frog’) facing upwards. Lay the first row of bricks, ensuring they are straight and level using the spirit level.
4. Build the rest of the wall
For single thickness walls, the simplest arrangement of bricks is called a stretcher bond. This is where bricks are staggered over the joints of the layer below, with half bricks used to finish off the ends.
When laying bricks, use a constant 1 centimetre thick layer of mortar in the joints and clean excess mortar off with a trowel. Keep the spirit level handy to ensure the bricks are level and square. If the bricks are too low raise up and add more mortar. If they are too high tap them down. Use the plumb line to check corners are vertical. Carry on laying rows of bricks until you have reached the desired height, finishing the joints before the mortar dries and using a smaller pointing trowel to neaten the finish. Do not rush; take the time to do it properly. It may take several days.
5. Finishing top or coping
The simplest way to finish a garden wall is to lay a top layer of bricks with the frog facing downwards or lay them vertically to create an attractive finish. Alternatively, use decorative coping or capping bricks that match the wall, engineering bricks, concrete caste coping slabs or narrow slabs that match your garden paving.
Running a piece of dowel across the joints and a using a stiff brush to remove excess mortar will neaten them up. Cover the wall with plastic sheeting to protect the mortar from the elements while it sets.
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