TECHNICAL INSIGHTS  ·  GLASS & GLAZING

Coated Glass: Why High-Performance Facades Need Specialist Care

The glass on a modern commercial facade is an engineered product. Treated as ordinary glazing, its performance can be permanently reduced by maintenance that was intended to protect it.

Contemporary facades rely heavily on coated glass. Solar control coatings reduce heat gain, low-emissivity coatings improve thermal performance, anti-reflective coatings manage glare, and self-cleaning coatings alter how the surface interacts with water and dirt.

These coatings are microscopically thin and, in many cases, chemically sensitive. They are also central to the building's energy performance, which means damage to them is not simply a cosmetic issue.

Hard coatings and soft coatings

Broadly, architectural coatings fall into two categories, and the distinction matters for maintenance.

Hard coatings are applied during manufacture while the glass is still hot, which fuses them to the surface. They are relatively durable and can generally be positioned on an exposed face of the glass.

Soft coatings are applied after manufacture in a vacuum process. They typically deliver higher performance, but they are considerably more vulnerable to abrasion and chemical attack. For this reason they are almost always positioned on an internal surface within a sealed unit, where they are protected from the elements.

The practical implication is that a soft coating is usually safe until the unit's seal fails or the glass is damaged. At that point, the coating is exposed and deterioration can be rapid.

How coatings are damaged

CHEMICAL DAMAGE

Strongly alkaline or acidic products can react with coating layers, causing clouding, staining, or patchy reflectance. Many general-purpose cleaning products fall into this category, and the damage is often not visible immediately. It becomes apparent later, usually when light strikes the facade at a particular angle.

ABRASIVE DAMAGE

Scouring pads, worn blades, and grit trapped beneath a cloth all leave fine scratches. On uncoated glass this may be tolerable. On a coated surface, the scratch removes coating material, and no amount of subsequent cleaning will restore it.

PRESSURE DAMAGE

High-pressure water applied at close range can drive moisture past gaskets and seals, and on some systems it can lift coatings at exposed edges. What was intended as a cleaning operation becomes the cause of a sealed unit failure.

Why the performance consequences matter

When a coating is degraded, the effects extend beyond appearance. Solar control performance falls, which increases cooling loads in summer. Thermal performance drops, which affects heating demand in winter. For buildings with energy performance targets or sustainability certifications, this represents a measurable decline in the asset's specification.

Patchy or uneven coating damage also has a visual consequence that is difficult to ignore. Because a facade is read as a whole, inconsistency across panels is far more noticeable than the same defect would be on a single window.

What appropriate care looks like

KNOW WHAT IS ON THE BUILDING

The first requirement is simply knowing what type of glass and which coatings are present, and on which surface. Without that information, any maintenance regime is working blind. This should form part of the building's handover documentation, though in practice it is often missing.

MATCH THE METHOD TO THE MATERIAL

Appropriate cleaning generally means pH-neutral products, clean water, soft applicators, and controlled technique. Where contamination is more stubborn, the correct approach is a specialist assessment rather than escalating to harsher products or more aggressive tools.

INSPECT AS WELL AS CLEAN

A specialist visit should identify early sealant fatigue, edge damage, seal failures, and signs of coating deterioration while remedial options still exist. Cleaning alone addresses appearance. Inspection addresses the asset.

Frequently asked questions