Metal cladding is as close to low-maintenance as a building envelope material gets. But low maintenance is not no maintenance — and a small amount of care at the right intervals is the difference between cladding that performs for decades and cladding that develops avoidable problems.
This guide covers what to inspect, how to clean different metals, and when something warrants a professional look. If an inspection has flagged something you’re not sure about, get in touch and we’ll help you work out what it is.
Why maintenance matters even for durable metals
Zinc, aluminium, copper, and steel all have strong natural or engineered defences against weathering. Under normal conditions they handle the British climate without issue. The problems that do occur are rarely the metal itself failing — they are almost always something interfering with the system: debris blocking drainage, fixings working loose over time, or incompatible materials causing localised corrosion.
Catching these early is straightforward and inexpensive. Leaving them unaddressed can lead to water ingress, structural damage, and repair bills that far exceed what an annual inspection would have cost.
Annual inspection: what to look for
Once a year — or after any significant storm — carry out a visual inspection of your metal cladding. You are looking for the following:
Blocked or damaged drainage
Gutters, outlets, and any drainage channels should be clear of leaves, moss, and debris. Standing water is the enemy of any cladding system regardless of material, and blocked drainage is the most common cause of moisture-related problems.
Damaged or displaced fixings
Thermal movement — the natural expansion and contraction of metal with temperature changes — works on fixings over time, particularly if the system was not correctly installed. Look for panels that appear to have shifted, visible gaps at seams or junctions, and any fixings that appear loose or corroded.
Sealant and joint condition
Where cladding meets windows, doors, or other elements, sealant joints manage the transition. Sealant has a shorter service life than the cladding itself — typically 15 to 25 years — and will eventually crack, shrink, or lose adhesion. Inspect these joints and replace any showing signs of deterioration.
Surface damage
Look for significant scratches, dents, or areas where a coating appears to have been breached. On coated steel, exposed metal at a damaged point can begin to corrode if left unaddressed. Minor scratches on zinc or copper will self-heal as the patina reforms; deeper damage should be assessed.
Staining or discolouration
Some staining is entirely normal — run-off patterns, early moss growth in shaded areas, or tannin staining from adjacent timber are all common and most can be removed with appropriate cleaning. Staining that recurs in the same location may point to a drainage or ponding issue worth investigating.
Cleaning metal cladding
For most buildings, an occasional wash-down is all that is needed. In the UK, rain does a reasonable job of keeping exposed surfaces clean naturally — buildings in urban areas or near busy roads may accumulate more particulate deposits and benefit from more regular cleaning.
The safest approach across all metal types is a gentle wash with clean water and a soft brush or cloth. For more stubborn deposits, a mild pH-neutral detergent can be used. Rinse thoroughly afterwards to remove any residue.
Avoid: abrasive cleaners, wire brushes, and high-pressure washers directed at seams or fixings. High-pressure washing can force water into joints designed to shed water from above — not resist it from the side — and can strip protective coatings on steel or damage the developing patina on zinc and copper.
Also avoid bleach-based or strongly acidic cleaning products unless specifically recommended by the cladding manufacturer. These can damage coatings, disrupt patination, and cause staining that is difficult to reverse.
Material-specific considerations
Zinc
Zinc’s protective patina should be left to form and mature naturally. Any cleaning approach that strips or disrupts the patina layer removes the material’s primary protection. The patina can look uneven in the early years on large elevations — this settles over time.
Aluminium
Powder-coated or anodised aluminium is straightforward to maintain. Periodic washing prevents the build-up of atmospheric deposits that can dull the finish over time. Both finishes are low-demand.
Copper
Copper requires very little intervention. The natural patination process is self-protective, and copper’s antimicrobial properties mean moss and algae are less likely to establish than on other surfaces. Avoid cleaning products containing ammonia, which can react with copper and cause staining.
Steel
Steel with a protective coating requires more vigilance than the other metals — the coating is doing the work. Any breach in it, whether from impact, incorrect cutting, or fixing damage, should be treated promptly. Small areas of exposed steel can be treated with a compatible touch-up coating; larger areas of damage should be assessed by a professional.
When to call a professional
Most routine maintenance is well within the capabilities of a building owner or facilities manager. But these situations warrant bringing in a specialist:
- You have water ingress and cannot identify the source
- Significant coating damage is present on steel cladding
- Fixings appear to have failed in multiple locations
- You are planning any work that requires access to or penetrations through the cladding
If any of these apply, get in touch with us — we can assess the installation and advise on the right course of action.
A simple maintenance schedule
| Frequency | Task |
|---|---|
| Annually | Visual inspection of full cladding area, drainage clearance, sealant condition check |
| Every 2–3 years | Full clean of the cladding surface |
| Every 15–25 years | Sealant replacement at junctions and transitions |
| As required | Touch-up treatment for coating damage on steel; professional assessment for water ingress |
Questions about your installation?
If an inspection has flagged something you’re not sure about, or if you want advice on maintaining a specific metal system, get in touch with the Met-Tec team. We work with zinc, aluminium, copper, and steel across London and the South East and can advise on the right approach for your installation.
