White marks on your brick wall are salt, not mould
The white bloom on brickwork is almost always efflorescence — soluble salts carried out of the masonry by moisture and left behind when the water evaporates. It is crystalline and powdery, not slimy, so it is not mould. Washing removes the deposit; only fixing the water source stops it returning. Schmick house soft washes start at $300.
The wall is sweating out its own salt
Efflorescence is not a coating that landed on your brickwork. It came out of it. Brick, mortar and the sand and cement behind them all carry soluble salts. When water moves through the masonry — rain driven into the face, moisture rising from the ground, a leak feeding the wall from behind — it dissolves those salts and carries them to the surface. The water then evaporates into the Sydney air and the salt cannot follow it. What is left behind is the white bloom.
The NSW Heritage salt-attack guide documents this cycle in sandstone and masonry, and the lesson it draws is the useful one: the deposit is a symptom of moisture movement, not a hygiene problem. New brickwork often blooms in its first year as construction water dries out, and that fades on its own. Brickwork that keeps blooming, season after season, is telling you water keeps arriving. The white is the receipt. Somewhere behind it, something is wet that should be dry.
Crystalline and powdery is salt; slimy and dark is growth
Run a dry finger across it. Efflorescence is crystalline. It powders under a fingertip, brushes off as dust, and usually sits heaviest along mortar joints, at the base of a wall, or in a band under a window. It shows up after wet weather and becomes more obvious as the wall dries, which is the opposite of what most people expect. The colour runs white to off-white, sometimes with a faint sparkle when low sun rakes across the brick.
Mould and algae behave nothing like that. They are black, green or grey, they feel slimy or furry rather than gritty, and they smear instead of powdering. They favour the shaded, slow-drying elevations — south walls, the side of the house behind the hedge — and they spread as a film across the face of the brick rather than tracking the joints. Plenty of Sydney walls carry both: salt low down near the ground, growth up in the shade. They need different treatments.
Cleaning removes the deposit, not the cause
A soft wash will take efflorescence off. Low pressure, the right solution for masonry, patient rinsing — the bloom lifts and the brick comes back to its actual colour. That is a real result and worth having, particularly before a sale or a paint job. But be clear-eyed about what it is. You are removing the salt already delivered to the surface. The mechanism that delivered it is untouched. If water is still moving through that wall, the bloom returns on its own schedule.
So go looking for the water before you book anything. A gutter or downpipe leaking against the wall. A garden bed built up above the damp course, so every watering soaks straight into the brick. Mulch or new paving bridging that course. Blocked weep holes at the base of a cavity wall. A cracked or bypassed damp course in an older place. Air-conditioning condensate running down the face. Fix the source and the wash becomes permanent instead of a recurring ritual.
Sealing a damp wall pushes the damage inside the brick
The tempting shortcut is a sealer. Coat the wall, lock the salt out, job done. The Heritage salt-attack guide warns against exactly that on affected masonry, and the reason is mechanical rather than fussy. Sealing a wall that is still taking on water does not stop the water — it stops the water leaving through the face. The salt then crystallises a few millimetres behind the surface instead of on top of it, and crystal growth inside a pore is strong enough to push the face of the brick off.
On site that failure has a name: spalling. Brick faces flake, mortar goes sandy, sandstone sheds in sheets. It costs far more than the bloom you were trying to hide, and no amount of cleaning reverses it. The same guide warns against blasting salt-affected stone for a related reason — abrasive cleaning strips the weathered outer skin and leaves a thirstier surface behind. On masonry that is already moving salt, gentle and patient beats aggressive every single time.
What the wash costs, and what it honestly buys
The numbers are plain. Schmick house soft washes start at $300, and most single-storey homes land between $420 and $960 depending on wall area. A second storey adds about 40% for the access and the time. If sandstone is in the mix — a base course, a garden wall, a heritage frontage — that is priced per job, because material, growth and access all move the figure. Bundling the wash with gutters or windows on one visit saves between 5 and 15%.
What you get is a clean wall and an honest read of it. We will tell you where the salt is concentrated, which usually points at where the water is getting in, and we will say plainly if the real answer is a plumber or a bricklayer rather than another wash. When you want the number, the instant quote returns a firm, bookable price in about 60 seconds, and it holds unless the place is materially different. The salt keeps arriving until the water stops.