Order too few bricks and you halt the job waiting for a second delivery that may not match. Order too many and you have pallets you cannot return. This guide gives you a repeatable method to estimate bricks and mortar for a wall, the waste factor to add, and the mistakes that throw the numbers off. You will finish able to size an order with confidence.

Start with wall area, not guesswork

Every estimate begins with net wall area. Measure the length and height of the wall, multiply for gross area, then subtract the area of any openings such as doors and windows. The result is the surface you actually need to cover.

The key number is how many bricks cover one square metre of wall, and that depends on brick size and whether the wall is a single leaf (half brick thick) or two leaves. For a standard modular brick laid in a single-leaf wall, a widely used planning figure is around 60 bricks per square metre including the mortar joint. Always confirm against your specific brick, because sizes vary by region and manufacturer.

Why the mortar joint matters

Estimates count the brick plus its share of joint, not the bare brick. A typical bed and perpendicular joint is about 10 mm. If your joints run thicker, you fit fewer bricks per square metre and use more mortar. This single variable is why two people can get different counts for the same wall.

A worked example

Say you are building a single-leaf garden wall 10 m long and 1.8 m high, with no openings.

• Gross area: 10 x 1.8 = 18 square metres
• Bricks at roughly 60 per square metre: 18 x 60 = 1,080 bricks
• Add 5 to 10 percent waste for cuts and breakage: at 7 percent, about 1,156 bricks
• Round up to full packs as sold, so you might order the next pack size above that

For a two-leaf (one brick thick) wall, double the brick count, because you are effectively building two skins. That same wall would need roughly 2,160 bricks before waste.

Estimating the mortar

Mortar is harder to eyeball because it fills bed joints, perpendicular joints, and any frogs or cores. As a practical planning guide, expect to use somewhere in the region of 0.02 to 0.03 cubic metres of mortar per square metre of single-leaf brickwork with 10 mm joints. Thicker joints, deep frogs, or rough handling push this up.

Rather than trusting one rule, cross-check. Many bricklayers plan mortar by counting how many bricks one bag of cement-based mix will lay, a figure the mix supplier usually states. Compare that against your area-based estimate and take the higher, safer number.

The waste factor, and why it is not optional

Waste is not padding. It covers cut bricks at corners and openings, breakage in transit and handling, and the reality that you want spares that match for future repairs. A sensible range:

• 5 percent for a simple straight wall with few cuts
• 7 to 10 percent for walls with corners, piers, or many openings
• 10 percent or more for intricate work, arches, or reclaimed brick that arrives inconsistent

Keeping a small stock of matching bricks after the job is worth the extra cost. Colour and texture drift between production batches, so a repair years later rarely blends if you did not keep spares.

Common mistakes and how to fix them

• Forgetting to subtract openings. On a wall that is mostly windows, this inflates the order badly. Fix: always deduct opening areas.
• Ignoring wall thickness. Estimating a two-leaf wall as single-leaf halves your order. Fix: confirm the wall build-up before counting.
• Using a generic bricks-per-metre figure for a non-standard brick. Fix: calculate from your actual brick face size plus joint.
• Zero waste allowance. Fix: always add a waste percentage matched to the job complexity.
• Mixing batches mid-wall. Ordering short and topping up later risks a visible colour band. Fix: order the whole job, plus spares, in one batch.

Action steps

• Measure length and height, calculate gross area, subtract openings
• Confirm your brick size and joint thickness
• Multiply net area by the correct bricks-per-square-metre figure for your brick
• Double it for a two-leaf wall
• Add a waste factor of 5 to 10 percent based on complexity
• Cross-check mortar two ways: by area and by bricks-per-bag
• Order everything, including repair spares, in a single batch

Conclusion

Accurate estimating is just area, brick size, wall thickness, and a realistic waste allowance, cross-checked before you commit. Do the math once, carefully, and order the full job in one batch. Your next step: measure your wall today and confirm your exact brick dimensions with the supplier before you calculate.

FAQ

How many bricks are in a square metre?

For a standard modular brick in a single-leaf wall with 10 mm joints, a common planning figure is about 60 per square metre. Verify it against your specific brick size, since dimensions vary by manufacturer and region.

How much extra should I order for waste?

Between 5 and 10 percent for most walls, leaning higher when the job has many corners, openings, or uses reclaimed brick. Keep some matching spares afterward for repairs.

Can I return unused bricks?

Sometimes, but often only full, unopened packs and subject to a restocking fee. Reclaimed or special-order bricks are frequently non-returnable, which is another reason to estimate carefully rather than heavily over-order.

Does joint thickness really change the count?

Yes. Thicker joints mean fewer bricks per square metre and more mortar. If you plan to work with wider joints for a particular look, recalculate rather than using the standard figure.

How do I estimate a two-leaf wall?

Calculate as if for a single leaf, then double the brick count, because a two-leaf wall is two skins of brick. Adjust mortar upward accordingly.

If a chalky white haze keeps appearing on your brick walls, you are looking at efflorescence: salt deposits carried to the surface by water. It is usually cosmetic, not structural, but it is a signal that moisture is moving through the wall. This article explains what actually causes it, how to remove it without damaging the brick, and the specific fixes that stop it returning.

What efflorescence really is

Efflorescence is not mold, dirt, or paint failure. It is soluble salts, mainly sulfates and carbonates, that were already inside the brick, mortar, or backing material. Three things must happen at once for it to appear: salts are present, water dissolves them, and that water travels to the surface where it evaporates and leaves the salt behind.

This is why efflorescence often shows up on new masonry in its first year, then fades. Fresh mortar and brick still hold construction moisture, and that water pushes salts outward as the wall dries. If it keeps returning long after construction, water is getting in from somewhere it should not.

Efflorescence vs. lime staining

People confuse the two. Regular efflorescence is a light powder that often brushes off dry and dissolves in water. Lime run (calcium carbonate) is harder, forms crusty streaks or drips, and does not dissolve in plain water. The removal method differs, so identify which one you have before you start.

Why it keeps coming back

A one-time bloom on new brick is normal. Repeated efflorescence points to a water source. Common culprits:

• Missing or failed damp-proof course letting ground moisture rise up the wall
• Cracked or eroded mortar joints allowing rain to enter
• Blocked or missing weep holes trapping water behind the brick
• Leaking gutters, downpipes, or a poorly flashed sill dumping water onto one area
• Sprinklers or splashback wetting the base of the wall daily

Notice the pattern of the staining. A horizontal band low on the wall suggests rising damp. A vertical streak under a window suggests failed flashing. A patch below a gutter joint points straight at the gutter. The location tells you where the water is.

How to remove it correctly

Order of operations matters. Always try the gentlest method first.

• Wait for dry weather, then brush the wall with a stiff, dry natural or nylon brush. Much loose efflorescence comes off dry.
• If some remains, use clean water and the brush, then let the wall dry fully. Do not soak the wall, or you simply feed more salt to the surface.
• For stubborn deposits, a proprietary masonry efflorescence remover (a mild acid formula) works, but always test a small hidden patch first and follow the product dwell time.

Two cautions from experience: pre-wet the brick before any acid cleaner so the acid stays on the surface rather than soaking in, and never use a strong pressure washer up close. High pressure erodes soft mortar and drives water deep into the wall, which causes fresh efflorescence weeks later.

A real scenario

A homeowner reported white patches returning every spring on a two-year-old garden wall, always along the bottom two courses. Cleaning worked for a few weeks, then it came back. The wall had no damp-proof course at its base and sat in a bed that pooled rainwater. The fix was not more cleaning. It was regrading the soil to drain away from the wall and capping the top to stop rain soaking down. Once the water stopped, the efflorescence stopped within one season.

Common mistakes and how to fix them

• Sealing over active efflorescence. Applying a sealer while salts are still forming traps moisture and can spall the brick face. Fix: solve the water source first, let the wall dry for weeks, then seal only if needed.
• Using household bleach. It does nothing for salts and can leave its own residue. Fix: use water or a purpose-made masonry cleaner.
• Aggressive pressure washing. Drives water in and damages joints. Fix: brush and rinse gently.
• Treating the symptom forever. Repeat cleaning without finding the leak wastes effort. Fix: read the stain pattern and trace the water.

Action checklist

• Identify whether it is soft efflorescence or hard lime run
• Map where the staining appears and what is above or below it
• Brush dry first, then rinse gently only if needed
• Find and fix the water source: gutters, flashing, weep holes, ground drainage, damp course
• Let the wall dry fully for several weeks before considering a breathable sealer
• Re-inspect after the next heavy rain to confirm the fix held

Conclusion

Efflorescence is a messenger. The white powder is easy to remove, but lasting results come from stopping the water that carries the salt. Start by reading the stain pattern this week, then fix the moisture source before you clean. Your next step: inspect the wall after the next rainfall and note exactly where it stays wet.

FAQ

Is efflorescence a sign my wall is failing?

Usually not. It is a cosmetic salt deposit, and a single bloom on new brick is normal drying. But if it recurs, treat it as an early warning of unwanted moisture and investigate the source.

Will it damage the brick over time?

The surface powder itself is harmless. The risk comes from the moisture behind it. Persistent water in the wall, especially with freeze-thaw cycles, can eventually spall the brick face, so the water is the real concern.

Can I just paint over it?

No. Paint or sealer applied over active salts will peel or trap moisture. Solve the water problem, let the wall dry, then coat only if you choose a breathable product.

How long until new brickwork stops blooming?

Construction-related efflorescence often clears within the first year as the wall dries. If it continues past that, the cause is ongoing water intrusion, not initial drying.

Does a sealer prevent it?

A breathable water-repellent can reduce water entry, but it is not a substitute for fixing gutters, flashing, or drainage. Seal only after the wall is dry and the source is addressed.