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How to Build
a garden wall

Whether it’s a smart edge for garden borders or to enclose a patio (see our project guide How to plan & lay paving) garden walling is a project that can be completed with a moderate skill level.
Kit
Tool List
  • Spade
  • Trowel
  • Shovel
  • Tape measure
  • String or twine and pegsSpirit level
  • Disc grinder
  • Bolster chisel
  • Lump hammer
  • Brick hammer
Safety equipment
  • Dust mask
  • RCD adaptor
  • Safety specs
  • Gloves
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Wear gloves and goggles when cutting or splitting bricks or blocks. Avoid breathing in dust when cutting bricks or blocks by wearing a face mask. Use an RCD device for power tools. If you are embedding lighting into your scheme, bear in mind that all electrical work must conform to BS 7671, the current IEE Wiring Regulations, and Part P of Building Regulations. You are advised to check with your local authority’s building control department, or an authorised competent person before starting. If in any doubt about electrical work, contact a qualified electrician.

1
Draw a plan

If the wall is part of a wider scheme, draw a scale plan. Mark in the walls of the house or large trees, and plan in all cabling and drain runs, which will need to be in position, underground and protected before starting.

 

Lay out the site

Transfer your plans into a full-size layout on the site, setting out with string lines and pegs. Wherever possible, plan the area so that you use full-size blocks or bricks to keep cutting to a minimum.

 

Use the right tools

If you will be cutting lots of bricks or blocks, use a 230mm disc grinder. Otherwise, you can use a lump hammer and bolster chisel. You will also need a spirit level at least 600mm long. See our full tool list (left).

 

Buy the right amount of walling materials

When determining how many bricks are required, first work out the brickwork area.

 

For a single skin wall – also known as a half brick wall (see Fig. 1 on page 2), allow 60 bricks per square metre. This style is known as stretcher bond with only the long ‘stretcher’ faces of the bricks visible.

 

For a one brick thick solid wall with the visible ends of bricks known as headers on show (see Fig. 2) – allow for 120 bricks per square metre.

 

These figures do not allow for wastage or breakage, so add 10% extra to the order to make certain you do not run short. Fig. 3, 4 and 5 show more information about calculating material quantities.

 
Skill level required

Laying bricks and blocks is not complicated but it does take practice to get a neat finish.

 

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Fig. 3 Calculate the bricks, blocks and mortar
Number of bricks & amount of mortar required (single skin of brickwork)
Sq m of brickwork 1 Number of bricks needed 60 Bags of Wickes’ bricklaying mortar (rounded up) 2.4 (3)
Number of bricks & amount of mortar required (solid one brick thick wall)
Sq m of brickwork 1 Number of bricks needed 120 Bags of Wickes’ bricklaying mortar (rounded up) 24.8 (5)
Number of blocks & amount of mortar required (single skin 100mm thick blocks)
Sq m of brickwork 1 Number of bricks needed 10 Bags of Wickes’ bricklaying mortar 2

 

Fig. 4 Mortar mixes for brickwork, blockwork & rendering (All ratios by volume)
Choosing mortar mixes for brickwork
Type of construction Proportions of Mastercrete cement/ building sand
External walls above damp-proof course level 1:5
External walls above damp-proof course level 1:4-5
Retaining walls 1:3
External freestanding walls 1:4-5
Choosing mortar mixes for blockwork
Type of construction Proportions of Mastercrete cement/ building sand
External walls above damp-proof course level 1:5
External walls above damp-proof course level 1:4-5
Retaining walls 1:3
External freestanding walls 1:4-5
Choosing a suitable mortar mix for rendering
Background material Mix Undercoat Topcoat
Low suction such as hard dense clay bricks, dense concrete blocks and stone masonry concrete Mastercrete cement sharp sand 1:3-4 1:5
Normal suction such as average types of bricks, clay blocks, concrete blocks and aerated concrete blocks Mastercrete cement sharp sand 1:5 1:6

 

Fig. 5 Calculate the number of bags of concrete mix required
Major bags concrete mix Produces approximately this amount of concrete
Major bags concrete mix Produces approximately this amount of concrete
15 0.19 cu m
30 0.38 cu m
45 0.56 cu m
80 0.56 cu m
Ratios of concrete mix
Use Equivalent ratios using cement and bags of all-in ballast
Foundations 2:8
Blinding layer for sub-floors etc 2:21
2
Preparing foundations
for a wall

These pictures show the best ways to construct a wall, depending on the landscape in which you are working.

 
A wall to edge a path

Fig.6 shows a simple wall or an edging to a path. Fig. 7 shows the layout of a wall with soil behind for plants, then paving. The foundations for the two walls are separate to allow drainage through to the ground below.

 

Building retaining walls

Fig. 8 and Fig. 9 show other ways of building retaining walls where the ground slopes away from a house wall.

 

Fig. 10 shows how to deal with ground sloping towards the house.

 

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Lay foundations for a wall

Plan to lay foundations during a dry spell, and avoid working with concrete if frost is predicted.

1. Measure up for foundations

Unless you are building on to existing concrete, you will need to provide adequate concrete foundations for the wall. The foundations should be 300mm wide and 225mm deep. The bricks or blocks will be laid along the centre of the concrete surface.

 

2. Dig out the trench

Use pegs and a string line to mark out the trench. Excavate a 300mm deep trench where the wall is to be.

 

3. Drive in pegs

Drive 450mm timber pegs into the centre of the trench at 1200mm to 1800mm intervals so that they finish about 25mm below ground level. Use a spirit level and straight-edge to ensure the tops of the pegs are level. They will serve as a guide when the concrete is laid, indicating the surface level.

 

4. Infill the trench

Pour the concrete up to peg level (see Fig. 11), tamping it level with the edge of a board, using the tops of the pegs as a guide. Leave the concrete to cure for at least 24 hours, covering it with polythene sheeting to keep any rain off, and also to prevent it drying out too quickly in hot weather.

 

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3
Building a wall

If this is the first time you have attempted to work with bricks or blocks and mortar, give yourself plenty of time to complete the job – and to finish the pointing neatly.

 

1. Mark out the wall’s position

Stretch a string line along the set concrete where the front edge of the wall is to finish. This will ensure that the first course is laid straight.

 

2. Mix your mortar

A good, general-purpose bricklaying/ blocklaying mortar is made with six parts sand to one part cement to one part hydrated lime (or, one bag of sand, mixed with one shovelful of cement and one shovelful of hydrated lime), plus mortar plasticiser in the mixing water.

 

For very hard materials, such as engineering bricks, especially in an exposed position such as a garden wall, a harder mortar mix is needed: four parts sand to one part cement with no hydrated lime. If mixing mortar by hand, mix the dry materials thoroughly together first on a board. Then make a well in the middle, add some water, and mix in. Do not add too much water. The plasticiser helps the mortar to flow without making it too wet, and the more you mix, the more it will flow. Use a shovel for mixing, not a garden spade.

 

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3. Begin the blockwork

Lay the blocks or bricks in the centre of the concrete, starting at one end and spreading the mortar to a depth of about 12mm behind the string line. The mortar should be workable but not sloppy. Lay the first end or corner block or brick in place and tap down gently, compressing the mortar to about 10mm. Check it is level (see Fig. 12).

 

4. Finish the first course

Continue laying the first course with 10mm mortar joints between each block or brick. Do not allow mortar to get on the faces of the blocks or bricks where it could cause staining. On a straight wall with no return corners, start the second course with a half block or brick (see instructions for cutting in step 6). On a wall with a corner (return), start the second course with one block or brick laid at 90° to the first course (see Fig. 13 for the two layouts).

 

You should be able to push or tap a block or brick down to create a 10mm mortar bed; if this is too much like hard work, you are probably using too much mortar or mortar that is too dry.

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Take time to get the first course of brick or block work right because it will affect the entire wall if you get it wrong. Ensure it is perfectly straight and level before you begin the second course (sometimes it helps to ‘dry-lay’ the first course to begin with).

 

5. Use a bricklayer’s line

For each course, bed the two end bricks or blocks, and level them using a straight board on edge with the spirit level on top. Then stretch the line between them (running from the front top edges) by wrapping it around two bricks and laying it on top of the end bricks. Then infill with the remaining bricks or blocks. As you progress, make sure the infill bricks or blocks are not touching the line and pushing it out of true (see Fig. 14).

 

 

6. Cut blocks or bricks to fit

To cut a block or brick, chip a groove all round the block or brick along the intended cutting line with a bolster chisel and lump hammer. Lay the scored block or brick on a sand bed, place the chisel in the groove then strike firmly with the lump hammer to split the block or brick. Or, use a disc grinder.

 

7. Lay the second course onwards

Continue building course by course, checking the blocks or bricks are level and in line both vertically and horizontally, keeping the mortar joints to an even 10mm thickness.

 

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8. Finish the pointing

When the mortar starts to set, either smooth it flush with the blocks or bricks using the rounded end of a piece of wood or a rake, or smooth back behind the block or brick face to a depth of about 6mm, using a trowel. This is a job that can generally be left for a while, depending on temperature, after the mortar has been laid, but take time to ensure it is neat.

 

9. Finish the wall

Cap the finished wall with coping stones, laid on a mortar bed.

If in doubt, make mortar mixes weaker rather than stronger. This is especially important when repairing or repointing older brickwork. Pre-1939 brickwork was usually built with sand and lime mortar (no cement). Re-pointing it using a strong cement-based mortar can damage it quickly, with the faces of the bricks blown off by movement and frost damage.