Landscape Design Ideas – Types of Garden Walls
Landscape Design Ideas – Garden Walls
Walls take longer to construct than it takes to plant a hedge, and it will almost certainly be more expensive. Both problems are, however, offset by the ease of maintenance afterwards. And in many situations a wall is more practical, and even more aesthetically pleasing, than a living screen. A wall, planted with suitable subjects, can combine the best of both worlds.
Brick Garden Walls
Start by sketching out the proposed design on paper, working to accurate dimensions. The standard size for a brick is 22.5cm long, 6.5cm high and 11.2cm deep (about 9in x 2-1/2in x 4-1/2in ). This is their nominal size, and it includes a 10mm (3/8in) allowance for mortar joints. Design your wall to nominal dimensions.
It’s difficult to be precise on foundations required, but as a guide a 40cm (15in) wide strip should be excavated for a wall up to 60cm (2ft) high. Dig until firm ground is found. Where stability is in doubt, lay a bed of well-compacted hardcore. Allow for a 7.5cm (3in) layer of concrete (one part cement: twoand-a-half parts sharp sand: four parts aggregate) with one brick to be below ground level. If the wall is to be over 1.2m (4ft) high, lay a 10cm (4in) layer of concrete with two bricks below ground level.
Mark out the wall line with two string lines pulled taut and tied to stakes. Use a mortar mix of one part of cement to five parts of builders’ sand. The mortar should be buttery (not too dry, nor too wet); it should retain its shape when spread from the trowel. A few drops of washing-up liquid will improve the mortar’s workability, but don’t mix up more than you can use in an hour — less on a hot day. Always keep wet concrete well away from drains.
Trowel enough mortar along the foundation to bed a couple of bricks. Lay the first brick frog (indentation) upwards, and check it for level using a spirit-level, making sure it is also aligned with the string lines. Trowel mortar on to the mating face of the next brick and lay this ensuring that the joint is 10mm (3/8in) thick. Place a spirit-level across both bricks; tap down the second brick to level using the handle of the trowel.
Subsequent courses should be laid to a string line secured with pins. Having completed the first course, build up the ends of the wall for three or four courses in stepped formation before finishing each course. To check that the vertical joints are being kept uniform, use a batten which is marked off in 6.5cm (2-1/2in) increments.
Where half bricks are needed they must be cut. Lay the brick (frog down) on a flat, solid surface and mark the cut line in pencil. Chip the brick at both ends of the marked line using a club hammer and bolster chisel. Place the bolster on the line, tilted towards the waste side, and cut through with a sharp blow from the hammer.
Point the joints between the bricks before the mortar hardens. Joints can either be left flush with the bricks, shaped downwards and outwards using a pointing trowel, or rounded off with an implement such as an old bucket handle.
Screen Block Garden Walls
These are made of precast concrete blocks. Various patterns are available. The blocks are 30cm square x 10cm thick (1 ft sq x 4in). This is the nominal size which includes a 10mm (3/sin) allowance for joints. Provide firm concrete foundations, using a mixture of one part cement to five parts 20mm (3/4in) ballast. For the mortar use one part cement to six parts sand, plus plasticizer.
Foundations should be a minimum of 20cm (8in) deep, including bricks or rubble where needed.
At each end of the wall, pilaster blocks are used. These are reinforced with metal rods and infill concrete (one part cement to three of ballast), which should be fluid enough to sink down into the pilasters.
Loose-lay the blocks between the pilasters to ensure they fit (don’t forget to allow for joints). Then lay the blocks as for brickwork except that you should work from both ends to the middle. Check each block for level, and again build up the corners before completing successive courses.
Finish with pilaster caps and coping slabs on the top course. Use a piece of hardwood with a rounded edge to point the joints.
Dry Stone Garden Walls
Imitation stone blocks for walling can be used to achieve the informality of a dry stone wall. The buff-coloured blocks are 52.5cm x 15cm x 10cm (21in x 6in x 4in) full size: half blocks are 26.2cm x 15cm x 10cm(10-1/4in x 6in x 4in).Coping slabs are used to complete the wall.
The blocks should be laid on firm foundations using a half-block to start alternate courses. Use a mortar mix of one part of cement to four parts soft sand. Joints should be about 6mm (1/4in) thick. Lay the blocks frog (depression) upwards. If the wall is to be higher than four courses, allow 48 hours for the mortar to harden before you begin laying the fifth and subsequent courses.
Dry stone walling blocks are also available for dry laying, that is, without mortar. These are sold as 600mm x 200mm x 70mm (24in x 8in x 2-3/4in ) blocks, and two are joined together when delivered; they must be separated using a wide bolster chisel and club hammer. Preformed v-shape rebates make this a simple task. On splitting, the limestone aggregate edges are revealed, and these should be left exposed as the wall is built. Cut the return ends in the same way.
A gravel or ballast foundation is adequate for a low wall, but a concrete foundation is needed for a wall over 60cm (2ft) high if it is intended to retain earth. Here, 12mm (1/2in) joints should be left between blocks.