How to Keep Brick Courses Level When Laying a Garden Wall

Keeping brick courses level when laying a garden wall comes down to three things: a solid, level foundation, the right tools, and a disciplined laying technique. Get these right from the start and your wall will look professional and stand the test of time — even in New Zealand's variable climate.

Start With a Level Foundation

No amount of careful bricklaying will save a wall built on an uneven base. Before you lay a single brick, make sure your concrete footing is:

• Level across its full width and length — use a long spirit level or a laser level to check
• Adequately sized — as a general guide, footings for a freestanding garden wall should be at least twice the wall's width and a minimum of 150 mm deep, but always check with your local council, as requirements vary by soil type and wall height
• Fully cured — allow at least 3–7 days before building on fresh concrete

If your footing has minor high spots, you can compensate slightly with your first mortar bed, but don't rely on this for large variations.

Essential Tools for Level Courses

Having the right gear makes a huge difference. You'll need:

• Spirit level (at least 900 mm long) — for checking individual bricks and short runs
• Line blocks and bricklayer's line — the most important tool for keeping long courses level
• Corner blocks (or pins) — to anchor the line at each end
• Gauge rod — a timber batten marked at regular intervals (typically every 75 mm for standard bricks plus a 10 mm mortar joint) to check course heights consistently
• Rubber mallet — for tapping bricks into position without cracking them
• Trowel — a good-quality brick trowel for spreading mortar
• Tape measure and builder's square — for setting out corners accurately

You can find most of these at Bunnings or Mitre 10.

The Line Block Method — Your Best Friend

Line blocks are the secret weapon of every experienced bricklayer. Here's how to use them:

1. Build your corners (quoins) first, checking each brick with your spirit level in both directions — side to side and front to back. Build the corners up 4–6 courses before filling in the middle.
2. Hook a line block onto each corner at the top edge of the course you're about to lay. Pull the bricklayer's line taut between them — it should be tight enough that it doesn't sag.
3. Lay each brick to the line, with the top front edge of the brick just touching (but not pushing) the line. Even a small amount of pressure on the line will throw your whole course out.
4. Check with your spirit level every 3–4 bricks to confirm level, and use your gauge rod to confirm the course height is consistent.
5. Move the line blocks up to the next course and repeat.

This method means you're not relying solely on your eye or your spirit level for every single brick — the line does the work across the full length of the wall.

Getting Your Mortar Consistent

Inconsistent mortar joints are one of the most common reasons courses go out of level. Aim for a 10 mm mortar bed joint throughout (standard for most NZ brickwork). Tips for consistency:

• Mix mortar to a firm but workable consistency — it should hold its shape when squeezed but not be crumbly or sloppy
• Spread a consistent thickness of mortar before placing each brick
• Use the same number of taps with your mallet to seat each brick
• Scrape off excess mortar promptly and reuse it

A common NZ mortar mix for garden walls is 1 part cement : 1 part lime : 6 parts sand (by volume), though pre-mixed mortar products are also available and convenient for smaller jobs. Check manufacturer guidance for the specific product you use.

Checking and Correcting as You Go

If a brick is sitting too high, tap it down gently with your mallet. If it's too low, lift it, add a little more mortar, and re-lay it. Never try to adjust a brick once the mortar has started to go off — you'll disturb the bond and weaken the joint.

NZ Climate and Building Code Considerations

In New Zealand, garden walls over a certain height may require a building consent — this varies by council and by the wall's location and construction type. As a general guide, freestanding walls over 1.5 m in height often require consent, but always confirm with your local council before you start. The MBIE Building Performance website has useful guidance on Schedule 1 exemptions.

In coastal or high-wind areas (common across much of NZ), consider using a stronger mortar mix and ensure your footing design accounts for lateral loads. BRANZ publishes research and guidance on durable construction in NZ conditions.

When to Call a Professional

Laying a small, low garden wall is a satisfying DIY project, but there are times when it pays to bring in a qualified bricklayer:

• The wall is over 1 m tall, retaining soil, or near a boundary or structure
• You need a building consent — a licensed tradesperson can help ensure the work meets the NZ Building Code
• You're unsure about footing design or soil conditions
• The wall involves complex corners, curves, or decorative features

A skilled bricklayer will work efficiently and get the result right first time. You can find qualified local bricklayers on tradedirectory.co.nz.

Sources & Further Reading

• MBIE Building Performance — Building Consent Exemptions
• BRANZ — Building Research
• Bunnings — Bricklaying Tools and Materials
• Mitre 10 — Masonry Supplies
• Standards NZ