Green staining on brick walls is algae that has rooted into the mortar and brick surface. Pressure washing just displaces it — soft washing kills it at the root so results last.
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Green staining on brick walls — exterior house walls, retaining walls, brick fences and feature walls — is algae that has established in the porous surface of brick and mortar. Brick is highly porous and provides excellent grip for algae and lichen spores, particularly in shaded, moist positions. Green staining on brick is extremely common in Queensland's humid climate and worsens progressively if left untreated, as the algae root system penetrates deeper over time. Soft washing with biocidal solution kills the algae at root level — pressure washing displaces the visible growth but leaves the root system intact, resulting in rapid regrowth.
Brick's porous surface provides excellent anchor points for algae and lichen spores. The calcium content of mortar is a food source for certain algae types. South-facing and shaded brick walls, brick retaining walls that retain soil moisture, and brick surfaces near garden beds stay moist longer and develop green staining faster than sun-exposed brick.
Brick retaining walls are among the most commonly affected surfaces — the soil moisture they retain keeps them damp and provides ideal conditions for biological growth. Green staining on retaining walls is both a cosmetic and a practical issue.
Mortar is more porous than brick and often shows green staining first. Algae that establishes in mortar joints can eventually penetrate the brick face. Soft wash treatment penetrates both brick surface and mortar joints to kill growth throughout.
Soft washing is safe for all brick types and for aged mortar that might be vulnerable to high-pressure washing. We match our pressure and chemistry to the specific brick and mortar condition.
Yes — soft wash with biocidal solution kills algae at root level and cleans the brick surface. Results last 12 to 24 months.
Yes — soft washing at low pressure is specifically safe for older brick where aged mortar might be vulnerable to high-pressure washing.
Yes — retaining wall cleaning is a regular part of our service.
Included in house washing from $499. Standalone retaining wall or fence cleaning available — contact us for a quote.
Based in Redlands, serving all of South East Queensland. Reply within 2 hours Mon–Sat.
0412 291 614