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Signs Your Cladding Needs Cleaning
Cladding rarely fails overnight — it dulls, greens and streaks first. Here are the signs that mean a wash is due, and what each one tells you.
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The clearest sign your cladding needs cleaning is that it no longer looks like itself: pale panels have turned grey or green, dark panels look patchy, and the building as a whole reads as uncared for. That change is gradual, which is why it is easy to miss until a neighbour's freshly washed facade makes the comparison unavoidable.
Beyond appearance, staining patterns carry information. Algae points to damp, shaded elevations; grey film points to traffic and dust; streaks below fixings point to deposits washing down the wall. Reading those signs tells you not only that a wash is due, but which method and which elevations need the most attention — see cladding cleaning methods explained for the full method-by-method breakdown.
Green and black staining
Green staining is almost always algae, thriving on damp, shaded panels — north-facing walls, sheltered courtyards, elevations under trees and canal or waterside frontages. Black spots and patches often accompany it, where mould and organic growth have settled into the panel texture. Both grow fastest in joints, laps and profiles, which is why they survive casual rain and need soft wash treatment to clear properly.
Left alone, algae holds moisture against the panel and its seals, keeping the surface damp long after rain has stopped. That persistent damp is what turns a cosmetic problem into a maintenance one, and it is the reason shaded elevations deserve inspection even when the sunny front of the building still looks clean.
Grey film, dull patches and streaking
A uniform grey veil across pale panels is usually traffic film and airborne dust, heaviest on road-facing elevations and around logistics yards. It dulls the whole facade evenly, so owners sometimes mistake it for the panel's natural colour — until a washed section reveals the original shade beside it.
Streaking tells a more local story: vertical marks below fixings, laps, sills and signage show where deposits have washed down and settled, or where water has run repeatedly over the same path. Dull patches that do not match their neighbours often mark where a previous partial wash stopped, or where a coating has weathered unevenly — both worth noting before the next wash, so expectations stay honest.
Signs that need more than a wash
Some signs point beyond cleaning. Panels that are bowed, cracked or loose, seals that have perished or pulled away, and fixings that are corroded or missing are repair issues, and washing alone will not fix them — though a wash makes them easier to see and assess. Rust streaks from fixings similarly suggest the fixing, not just the panel, needs attention.
If you spot these during an inspection, mention them before booking a wash. A good cleaning team will flag damage as it is found, clean around it carefully, and tell you plainly what washing can improve and what genuinely needs repair, so the facade ends up honestly better rather than merely cleaner-looking.
Discolouration that survives a proper wash is also informative: it may indicate coating failure, water staining from a leak above, or a panel that has weathered past cleaning. Noting which marks remain after washing gives a repair contractor a head start, and it stops owners paying for repeat washes chasing a stain that was never dirt.
Related guides
Guide
Cladding Cleaning Methods Explained
Soft wash, pressure wash, chemical treatment and high-level access — every cladding cleaning method, how it works and when it is used.
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Cladding Cleaning for Warehouses & Industrial Units
Warehouse cladding cleaning: large metal facades, yard logistics, access equipment and scheduling around deliveries and shifts.
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Preparing Your Building for a Cladding Clean
How to prepare for a cladding clean: access, water, vehicles, windows, plants and what to tell the cleaning team before they arrive.
Read the guide →Frequently asked questions
What are the first signs cladding needs cleaning?
The first signs are usually subtle: pale panels turning grey with traffic film, green tinges on shaded walls, and streaks below fixings and sills. The building starts to look dull or patchy rather than damaged. Catching it at this stage means a straightforward wash, before algae roots into joints or film becomes ingrained.
Why is my cladding going green?
Green staining is algae growing on damp, shaded panels — north-facing walls, sheltered courtyards, elevations under trees and waterside frontages are most affected. Algae thrives where panels stay wet, and it settles into joints and profiles. Soft washing treats it at its roots, and improving sunlight or drainage where possible slows its return.
What causes grey film on cladding?
Grey film is usually traffic exhaust deposits and airborne dust settling on the panels, heaviest on road-facing elevations and near logistics yards and busy junctions. It dulls pale panels evenly across the whole facade. A full, even wash lifts it; spot-cleaning only the worst patches leaves visible mismatches across the wall.
What do streaks on cladding mean?
Streaks below fixings, laps, sills and signage show where deposits or rainwater have run down the same path repeatedly, leaving marks as they dry. They are common on tall and road-facing elevations. A thorough wash clears most streaking, but streaks caused by corroded fixings or damaged coatings may need repair as well as cleaning.
Can dirty cladding damage the building?
Yes, over time. Grime and algae trap moisture against coatings and seals, keeping panels damp and encouraging further growth, while ingrained deposits become harder to remove. Dirty cladding can also hide developing damage to panels, seals and fixings. Regular washing keeps the facade presentable and makes problems visible while they are still small.
How do I inspect my cladding for cleaning needs?
Walk around the whole building, not just the front, and look at every elevation in daylight: green growth on shaded walls, grey film on road-facing walls, streaks below fixings, and dull patches. Check joints, laps and sheltered ledges closely, since staining hides there. Note anything bowed, cracked or loose for repair assessment too.
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