Material-aware cleaning that protects coatings, sealants and stone
A building's facade is the first thing anyone sees, but appearance is not the main reason to keep it clean. Cleaning is preventative maintenance: it removes the acidic deposits that permanently etch glass, pit metal and degrade the sealants keeping the building watertight.
It is also the point at which a great deal of expensive damage gets done. Abrasive pads on coated glass, acidic cleaner on aluminium, high pressure on masonry — each of these causes permanent damage that costs far more than the cleaning saved.
We come at this from the glazing side. We know what the coatings on your glass are, what will damage them, and whether staining that is already there can be removed or whether the glass needs replacing. That judgement is the part most cleaning contractors cannot give you.
Urban air carries sulfur dioxide, nitrogen oxides, carbon particulates and, near the coast, chlorides. Combined with rain, dew and humidity, these form acidic compounds that sit on the building and attack it.
Glass corrosion. Glass is less inert than it looks. Acidic deposits first produce a light haze that still cleans off. Left long enough, the attack etches into the glass surface itself, producing permanent iridescent staining that no cleaning will remove. At that point the only remedy is polishing, which is expensive and not always successful, or replacement.
That progression is the single strongest argument for scheduled cleaning rather than reactive cleaning. Once staining is etched, the money is spent whether you clean or not.
Metal corrosion. Aluminium cladding, stainless accents and bronze pit and corrode when acidic deposits and chlorides are left to dwell on them. Coastal buildings suffer this fastest.
Masonry decay. Limestone, precast and brick are porous and absorb acidic moisture. That produces efflorescence — salt deposits on the surface — and more damagingly subflorescence, where salt crystallises inside the stone and the pressure spalls the face off.
Sealant degradation. The building stays watertight because of its sealant joints. Pollutants and UV together break those down, and chemical buildup accelerates it. Cleaning removes the accelerant. See waterproofing for what happens when those joints fail.
This is where we add most value, because it is where most damage happens.
Modern high-performance glass carries Low-E and solar control coatings. The great majority of these are soft coat — sputtered layers of silver and metal oxides just nanometres thick. They are extraordinarily effective and physically delicate.
In a sealed unit those coatings sit inside the cavity, protected. But surface four coatings face the room, and monolithic coated glass may carry a coating on an exposed face. Those get cleaned, and they scratch.
The rules are simple and routinely broken. No abrasive pads. No scrapers on coated surfaces. No harsh alkaline detergents. Plenty of lubrication so grit is floated off rather than dragged across the surface. Scratches in a coating are not repairable — the pane is replaced.
Structural silicone is the other hazard. Where glass is held to the frame by structural silicone, the cleaning agent has to be chemically compatible with that sealant. An incompatible chemical degrades the bond holding the glass in place, which is a structural problem rather than a cosmetic one. See property energy performance for how these systems are assembled.
Spandrel glass needs its own care. Spandrel panels are opaque and sit in front of insulation or slab edges rather than conditioned space, so they run considerably hotter than the vision glass beside them. Detergent dries far faster on a hot spandrel, which raises the risk of chemical etching. It needs working in smaller sections and rinsing sooner.
A facade is a mosaic of materials, and one detergent at one pressure across all of them will damage something.
| Material | Correct Approach | What Damages It |
|---|---|---|
| Coated glass Low-E, solar control | Non-abrasive, pH-appropriate, plenty of lubrication | Abrasive pads, scrapers, harsh alkaline cleaners |
| Aluminium and ACM | Neutral pH, gentle agitation | Acidic or strongly alkaline cleaners — pitting and clouding |
| Stainless and bronze | Neutral pH; direction-aware on brushed finishes | Chlorides left to dwell; abrasives across the grain |
| Masonry and precast | Low-pressure soft wash with biodegradable detergent | High pressure — erodes mortar, drives water into the substrate |
| Structural silicone joints | Chemically compatible cleaners only | Incompatible solvents degrade the seal holding the glass |
The masonry point deserves emphasis because it is the most common expensive mistake. High-pressure washing on brick or precast erodes mortar joints, drives water deep into the substrate where it causes problems later, and can spall the face. Porous materials want low pressure and a biodegradable detergent given time to work on algae and atmospheric staining, then a gentle rinse.
Reaching the work is often the harder half of the problem, and the method chosen affects both cost and what is achievable.
| Method | Typical Range | Suits | Constraint |
|---|---|---|---|
| Water-fed pole | Ground to roughly 60–70 ft | Low and mid-rise; operator stays on the ground | Height limited; needs ground access to each elevation |
| Aerial work platform | Up to roughly 10–12 storeys | Buildings where roof rigging is not possible | Needs clear, load-bearing ground space |
| Building maintenance unit | Full height | Recurring cleaning where a roof BMU is installed | Requires trained operation and current safety inspection |
| Industrial rope access | Full height | Complex geometry, overhangs, restricted ground | Requires IRATA or SPRAT certified technicians |
Water-fed pole systems deserve a note because the technology is better than it sounds. Ultra-light carbon fibre poles carry brushes fed with purified water — run through reverse osmosis and deionisation to strip out every dissolved mineral. Ordinary tap water leaves spots because of the calcium and magnesium in it; pure water does not, so the surface is simply rinsed and left to air-dry with no squeegee and no detergent. The operator stays on the ground, which removes the ladder risk entirely for lower floors.
Rope access looks dramatic and has an excellent safety record when carried out by IRATA or SPRAT certified technicians working to protocol, with every technician on a redundant safety line. It reaches overhangs, recesses and geometry that platforms cannot, and it needs almost no ground footprint.
For work over the public way in New York, access frequently requires a sidewalk shed and the associated permits — see permits and access.
Facade cleaning is a regulated activity. Under the Clean Water Act and local codes, water carrying detergent, dirt or debris into a storm drain is illicit discharge.
In dense urban locations that means containment: dams or vacuum recovery at the base of the work zone to capture runoff, which is then either treated on site or tanked away for disposal.
The industry has largely moved to biodegradable, pH-neutral detergents, which reduce the problem without giving up cleaning performance. Pure water systems avoid it almost entirely, since there is no detergent in the water to begin with.
The question is not whether to clean but how often, and waiting until a building looks dirty usually means waiting until some damage is already permanent.
Exposure drives it. Coastal buildings taking salt spray need washing far more often than inland ones — frequently quarterly. Urban buildings near highways or industry generally want semi-annual attention. Sheltered suburban buildings can often run annually.
Architecture matters too. Deep sills, overhangs, reveals and complex geometry trap dirt and hold moisture against the surface, so an articulated facade needs more frequent attention than a flush curtain wall.
And standard. A Class A building competing for premium tenants maintains a different visual standard from a Class B asset, and that is a commercial decision rather than a technical one.
We would rather survey the building and propose an interval based on what we actually find than sell a standard package.
Cleaning sits in the operating budget and is easy to defer, which is precisely why the damage argument matters.
Avoided restoration. Routine cleaning costs a fraction of glass restoration or panel replacement. Once pollutants have etched glass or pitted metal, the remedy is measured in tens or hundreds of thousands rather than thousands.
Daylight. Dirty glass measurably reduces visible light transmittance. A building designed around daylighting does not deliver it through soiled glazing, which pushes up lighting load and affects how the space feels.
Asset perception. A stained facade reads as deferred maintenance, and that reading follows a building into appraisals and lease negotiations. It is one of the few maintenance items that is visible to everyone who walks past.
Ask us for a facade assessment rather than a cleaning quotation. If some of your glass is already etched we will tell you that, because cleaning it will not fix it and you should know before you spend the money.
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It depends whether the staining is a surface deposit or has etched into the glass. Surface deposits from mortar, concrete runoff or hard water can often be removed. Etched damage is permanent and the glass needs replacing. We assess before quoting.
Never with abrasive pads, and not with acidic cleaners on some coatings. Coated surfaces scratch easily, and damage to a coating is not repairable.
Hard water deposits. Caught early these can be removed and the glass treated. Left long enough, the minerals etch the surface permanently.
Yes. Post-construction cleaning removes site debris, adhesive residue and splash without scratching, which matters because ordinary site cleaning frequently damages new glass.
Tell us about the opening and we will specify it for you.
