How Bricklaying Adds Up: Bonds, Mortar, and Where the Count Comes From

Where "60 bricks a square metre" comes from

Ask any bricklayer how many bricks you'll need and you'll hear a confident "about sixty a square metre." It's one of those trade rules of thumb that sounds like folklore but is actually solid arithmetic — once you account for the fact that a brick wall isn't made only of bricks. It's bricks plus mortar, laid in a pattern, and all three of those shape the count.

The brick is bigger than it looks

A standard brick is a specific size, but when it's laid it doesn't occupy just its own dimensions — it occupies its size plus the mortar joint around it. With a standard 10 mm joint, each brick effectively claims a little extra in every direction, which is why the real-world count is slightly lower than dividing the wall area by the bare brick face would give.

Run that calculation for a standard modular brick with 10 mm joints and you land at roughly 60 bricks per square metre of single-leaf wall, or about 6.9 per square foot. The mortar isn't an afterthought in the estimate — it's part of what tiles the wall, which is exactly why counts are always quoted for a stated joint thickness. Thicker joints, fewer bricks; thinner joints, more. The Brick Calculator builds this in, and lets you set your own per-area figure if your bricks differ.

Bonds: pattern, strength, and appearance

A bond is the pattern in which bricks are laid, and it's one of the oldest ideas in construction. Common ones include:

• Stretcher bond — every brick laid lengthwise, the standard for modern cavity walls.
• English bond — alternating rows of stretchers and headers (bricks end-on), very strong.
• Flemish bond — stretchers and headers alternating within each row, prized for its appearance.

For a single-leaf wall, the number of brick faces you see per square metre is much the same whichever bond you pick — so the face count rule holds. Where bonds differ is in how many bricks go into the wall's thickness: patterns that show lots of headers are tying a thicker wall together and use more bricks overall. So bond mainly drives strength and looks, with the headline per-square-metre face figure staying fairly stable.

Single leaf versus cavity walls

This is the distinction that most changes a brick order. A single-leaf wall is one brick thick — think a garden wall. A cavity wall is the standard for modern house exteriors: two separate leaves with a gap between them for insulation and to keep damp out.

A cavity wall obviously needs more brick than a single leaf — roughly 1.5 to 2 times as much — though in practice the inner leaf is often blockwork (larger, cheaper concrete blocks) rather than brick, which changes the mix. The key planning step is being honest about which you're building before you count, because estimating a cavity wall as a single leaf will leave you badly short.

Don't forget the openings — and the waste

Two adjustments turn a rough area figure into a real order:

• Subtract large openings. Doors and windows are holes in the wall; leaving them in overcounts, especially on a small wall with big openings.
• Add a waste allowance. Around 5% for a simple rectangular wall covers cutting at corners and openings plus the inevitable breakages. Walls with piers, returns, or decorative detail waste more, so 7–10% is safer.

As with tiles, brick colour can vary between production batches, so buying enough in one go — and keeping a few spares — protects you against a visible mismatch if you ever need a repair.

A quick worked example

A wall 10 m long and 2.4 m high is 24 m² of single leaf. At 60 bricks/m² that's 1,440 bricks; add 5% waste and you'd order about 1,512. Subtract a door opening (say 2 m²) first and the figure drops to around 1,440 with waste — the openings genuinely matter at this scale. The Brick Calculator runs this from either the wall dimensions or a known area.

Estimating your wall

Enter the wall size (or area), brick type, and waste margin into the Brick Calculator for the brick count. If the wall sits on a footing, the Concrete Calculator covers the foundation beneath it.

Sources

1. Brick Development Association. Technical guidance on brickwork and bonds.
2. The Brick Industry Association (BIA). Technical Notes on Brick Construction.
3. Eurocode / local masonry standards — joint thickness and wall construction conventions.

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This article is for general informational purposes. Structural masonry should follow a qualified professional's design and local building codes.