How to build a brick garden wall

Inspired by a thorough UK bricklaying walkthrough. This guide draws on "How to Build a BRICK GARDEN WALL from Start to Finish", an in-depth tutorial from the Bricklaying With Steve and Alex channel. Their commentary covers every stage from the dig-out to the coping, and the close-up footage of laying and jointing is genuinely useful for anyone having a first go at this.

1. Plan the wall and check permitted development rules

In England, a garden wall up to 1 m high near a highway, or 2 m elsewhere on your property, generally falls within permitted development and does not need planning permission. Mind you — if you are on a boundary with a neighbour, the Party Wall Act may apply even for low walls. Check before you dig.

Mark out the wall line with a string line and pegs. A half-brick wall (single course of bricks, 102 mm thick) is fine for low decorative walls up to about 600 mm. Anything taller should be a full-brick or cavity wall for stability.

2. Dig the footings trench

Dig a trench at least 450 mm deep for a low garden wall, deeper if the soil is clay or on a slope. The trench should be about three times the wall width — so 300 mm wide for a half-brick wall. Clear all topsoil and soft material from the base.

Check the bottom of the trench for tree roots. A root within a metre of the wall can push through the footing within a few years if the tree is large enough.

3. Pour and level the concrete footings

Mix a stiff concrete at a ratio of 1 part cement to 6 parts ballast (all-in aggregate). Pour the concrete to a depth of 150 mm in the trench and tamp it level with a batten. The top of the footing should sit at or just below ground level so the first course of brickwork starts on solid material, not exposed concrete.

Allow the concrete to cure for at least 48 hours before laying bricks — 72 hours in cold weather. Do not lay bricks on fresh concrete. It will move.

4. Set up a string line and lay the first course dry

Stretch a builder’s line between profile boards or pins at each end of the wall. Set it at the height of one brick plus one mortar joint (typically 75 mm for a standard UK brick). This is your guide for the first course.

Dry-lay the first course without mortar to check your brick spacing. A standard 10 mm joint means you can calculate how many bricks fit the length. Adjust the joint width slightly rather than cutting half a brick at the end if you can avoid it.

5. Mix mortar and lay the first course

Mix mortar at 3–4 parts sharp sand to 1 part cement for general brickwork. Add a small amount of plasticiser for workability. The mix should be firm enough to hold its shape when squeezed but not crumble dry.

Spread a 10 mm bed of mortar on the footing along the full length. Butter one end of each brick before placing it. Set each brick firmly onto the bed, align it to the string line, and check it is level with a spirit level. Tap down gently with the handle of your trowel.

6. Build up the courses, checking plumb and level throughout

Each course should overlap the one below by half a brick — this is called stretcher bond and gives the wall its strength. Use a spirit level both horizontally along each course and vertically against the face of the wall. Check regularly — errors compound quickly and are difficult to fix once the mortar has set.

Keep moving the string line up as each course is completed. Work from both ends toward the middle if the wall is longer than about 2 m. Cut bricks as needed with a bolster chisel and club hammer, or hire an angle grinder with a diamond disc for cleaner cuts.

7. Strike the mortar joints

When the mortar has stiffened slightly — firm to the touch but not hard — run a pointing tool or the handle of your trowel along each joint to compact it. A concave or flush finish both shed water reasonably well. A rough, unfinished joint traps water and is the first place freeze-thaw damage starts in a UK winter.

Clean mortar smears off the face of the bricks with a damp brush before the mortar fully hardens. Dried mortar on brick faces requires acid cleaning to remove and can stain lighter bricks permanently.

8. Finish with a coping

The top of the wall needs protection from rain. Lay bricks on edge as a soldier course, use purpose-made concrete or stone coping blocks, or cap with engineering bricks set in a slight slope to shed water. A wall without a proper coping will erode at the top within a few years from frost action.

Point up any joints on the coping carefully and check the mortar is fully struck. This is the part of the wall most exposed to weather, and the most important to get right.

When to call a handyman

Call Richard if the wall is taller than about 600 mm, is on a boundary, needs to retain soil on one side, or if the ground is uneven or on a slope. Retaining walls carry lateral pressure from the soil and need engineering consideration that a standard garden wall does not. Some jobs need a professional.