Building a free-standing garden wall is really satisfying and can improve and secure your garden. Sometimes garden walls can need some extra strengthening - for instance, if it's a retaining wall that's holding back heavy earth, or if it's a particularly long wall or if it's attached to your house. Our guide will help with all of these wall-building and repair techniques.
If you're building a double-skin brick wall using stretcher bond, your first two skins will be tied together with wall or butterfly ties. Use engineering bricks for the first two courses below ground level, and frost-resistant F category bricks above ground. Mix some mortar and put it on a board supported on bricks (this is called a 'spot' board) at a convenient distance from the wall. Wet the board first to stop the mortar from sticking to it.
Attach lines to the inner nails on the profiles (the ones marking the edge of the wall). Then hold a spirit level upright against these lines and mark the outer edge of both skins of brickwork on the concrete. Join the marks using a length of timber as a straightedge.
Next, place a trowel full of mortar on the footing at the corner or end of line mark for the outer skin. Drag the point of the trowel towards you through the mortar, making a furrow in the centre. Then lay your first brick, frog (indented)-side up if it has one. Level this brick along its length and across its width using a spirit level.
After this, use a long spirit level to set another brick in position about a metre away from the first. This is a temporary brick which you can reposition later. Continue along the line, checking the bricks are level, until you can set the end-of-line brick in position.
Drive two line pins into the ground at each end of the wall, and then stretch a builder's line between them as a levelling guide. (If you've got a laser level you can use it to level from one end of the wall to the other quickly.) Next, fill in the gaps in the first course and move the temporary bricks as necessary.
Repeat the process to set out the first course of the inner skin. Use a builder's square to check that the corners are true right-angles.
Use your gauge rod to make sure the mortar in every joint between the bricks is 10mm thick - you'll get better at judging this with practice. From time to time, it's a good idea to get your spirit level and check the wall is straight and level.
Scoop up a sausage shape of mortar and make it roughly the size of the trowel blade. Then slide your trowel underneath the mortar and transfer it to the top course of bricks. Use the flat back of the trowel to stretch the mortar along five or six bricks, and then make a furrow in the centre with its point. Take off any mortar that's overhanging the edge of the bricks.
Pick up a brick with one hand and put mortar on the end with your trowel.
Push the brick into the mortar and give it a tap with the trowel handle. Aim for 10mm-wide horizontal and vertical joints. If a brick is too low, take it off and add more mortar. Lay the top front edge of the brick to the line, without quite touching it.
Scrape away any excess mortar from the front of your wall with a quick upward movement of the edge of your trowel.
When your first course is in place, you can lay the corners and ends of your wall.
Top tip - Builder's line
When you're using a builder's line, bend a small, thin piece of card in two, wrap it around the line and rest a brick on top. This keeps the line exactly on the edge of your bricks.
At each right-angled corner, lay three bricks in each direction and build up the corners with a series of five or six steps. Check the height of each course with a gauge rod.
Use your spirit level to make sure your wall is vertical, and your builder's square to check the corner is a true right-angle. To tie the two skins of the wall together, lay metal wall ties at intervals in the mortar. They shouldn't be more than 900mm apart on the horizontal plane and 450mm apart on the vertical. (English and Flemish bonds don't need wall ties.)
Check your steps are lined up by holding a straightedge or spirit level against the sides of the wall. When you've finished the corners, you can build the straight sections. Push two line pins into the vertical joints at each end of the wall, then stretch a bricklayer's line between them as a guide to level the top of the second course. Lift the line as you finish each course, and fill the join between the two skins with mortar as you lay them.
Pointing is the act of smoothing the mortar between the bricks to make it look attractive. This also packs the mortar into the joints and makes them watertight. There are different pointing finishes, but the most common is the concave or rubbed joint.
Leave the mortar until it's semi-dry. You can test it by pressing your thumb into a joint - it should leave an impression without the mortar sticking to it. Scrape a concave recess into the joint by using a jointing tool, or even a bucket handle or piece of metal.
Let the shaped joints harden a little, then gently brush away any loose bits of mortar with a medium-soft banister brush. Take care not to dislodge the mortar in the joints.
You can use bricks, stones, slabs or special coping bricks and blocks to finish your wall. Coping is a top course that overhangs, while capping lies flush.
Bed one stretcher face (the long, narrow side) of each brick into the mortar so it spans the width of the wall, and so that the header faces (the short sides) are flush with the faces of the wall. You'll need to use very strong mortar for your capping.
Slabs on a low garden wall can give you extra seating. When you lay them, make sure they overhang the brickwork by 25mm-30mm, and that you lay them on a continuous bed of mortar. Always wet the back of the slabs - particularly on hot days, as this helps them stick to the mortar. And you can use a line and spirit level in the same way as you do for the wall itself.
You'll need to include supporting piers, spaced no more than 3m apart, when you build a single-skin wall over 450mm high. You can also use them in double-skin brick walls as a decorative 'full stop' on which you can put a statue or potted plant, or as supports for gates or uprights for a pergola. (They're essential in double-skin walls of 1.35m and above.) The piers we're showing here are built in single-skin walls. Use stretcher bond, and repeat the first two courses until your pier is the required height.
To make a solid pier that projects on one side only, lay two header bricks in place of one of the stretchers on the first course, so they project from the wall. On the second course, cover the projecting part of the headers with a stretcher and cover the inner part with two three-quarter brick stretchers, with a half brick between them.
Solid end pier
To build a solid pier at the end of the wall that only projects on one side, lay a header brick against the end stretcher on the first course. Place a half brick parallel to the stretcher, butted against the header. On the second course, lay two stretcher bricks side by side.
Centred hollow end pier
End the first course with two three-quarter brick headers. Butt a stretcher against each one, flush with the outer edge, and position a half brick stretcher to complete the final side of the square. On the second course, lay two three-quarter brick headers on that final side and butt a stretcher brick against each one, flush with their outer edges.
Weather conditions and ground settlement can cause movement in a brick wall, resulting in serious cracks. Control joints help to prevent this. A control joint is a continuous vertical gap of unmortared joints, completely separating one section of wall from the next. You won't need them in a non-structural garden wall of less than 6m. In a wall longer than that, you should include them at 6 metre intervals. The width of the control joint is normally 10mm, or a minimum of 1mm per metre of walling.
Each control joint should run right to the top of your wall - including the coping, but not into the footing. They're easier to disguise if you position them where your wall meets an intermediate pier. Build your wall and pier in the usual way, but instead of mortar insert a 10mm-thick polystyrene strip in the vertical joint between them. Then embed galvanised metal strips with special debonding sleeves in the mortar of the horizontal joints, to allow for any slight movement.
When you've finished your wall, run a bead of mastic masonry filler into the joint on both sides to hide the polystyrene strip.
The easiest way to join a wall to another at right-angles is by using stainless steel connectors bolted to your existing wall. Special wall ties bedded in the new wall will secure it to the connector. You'll need a damp-proof course (DPC) in the garden wall or it could bridge the house's damp-proof course. Use a roll of polythene damp-proof course that's the same width as your wall.
Start by building the first few courses of your garden wall up to the level of the damp-proof course in your house wall. Lay damp-proof polythene down on the new wall at this level, sandwiching it between layers of mortar and lapping it up the wall of the house by the depth of one brick.
Next, use expanding masonry bolts to fix the stainless steel connector to the wall of your house, just above the damp-proof course.
Mortar and lay the end bricks against the connector so you form a joint with the existing wall.
At every third course, hook one of the wall ties onto the steel connector and bed the other end in the mortar on the new wall.
You can use a retaining wall to hold back a bank of earth and, in turn, create terracing on different levels in your garden. If you have a particularly steep bank, you hold it back with a series of small walls rather than one tall one. But don't attempt to build any retaining wall over one metre high without getting professional advice first.
Natural stone, bricks, concrete blocks and reconstituted stone are all suitable materials. But if you need a particularly strong wall, it's wise to set reinforcing rods or bars in the footing concrete. Excavate enough soil to give you room for the footing and the wall. If the soil in the bank is loose, hold it back with plywood or corrugated iron secured with metal pegs while you build your wall. Leave enough room to pack CleanStone (grit- and dust-free aggregate) between the back of the wall and the soil, and allow a 300mm depth of top soil.
Good drainage is very important for retaining walls. To achieve this, you can either leave some joints unmortared at ground level or just above to create weep holes, or fit a drainage pipe through the wall. You'll also improve drainage by putting a layer of geotextile permeable fabric on top of the CleanStone.
Hollow block and brick walls
Built with hollow concrete blocks and bricks, this type of retaining wall has reinforcing rods running through the holes in the blocks. Metal wall ties join the blocks and bricks.
Brick retaining walls
Reinforcing rods are set between the two skins of this double-skinned brick retaining wall. Metal ties join the two skins of bricks.
Concrete block and reconstituted stone walls
The inner skin of this wall is made from concrete blocks and the outer (facing) skin from reconstituted stone. The skins are joined by metal ties, and drainage pipes are fitted about one metre apart.