Tempered glass in shower enclosures: what CE marking and EN 12150 guarantee

When you choose a shower enclosure, the usual thing is to look at the model, the finish of the profile or whether it is fixed, hinged or sliding. It is rarely asked what glass is mounted and what regulations support it, and yet it is the piece that most directly affects the safety of the bathroom. Tempered safety glass is not a technical whim: it is a fundamental requirement that any well-manufactured shower enclosure must meet, and which is regulated by a specific European standard, EN 12150, in addition to the marking that the glass itself must have engraved.

What is tempered glass and why is it used in shower enclosures?

Tempered glass, also called tempered safety glass, is obtained by heating a sheet of annealed glass (the "normal" glass) to a high temperature and then cooling it in a rapid and controlled manner. This thermal process introduces internal tensions: the surface of the glass is in compression and the core in tension. The result is a material several times more resistant than ordinary glass of the same thickness against impacts, sudden changes in temperature and bending, making it suitable for frequent domestic use such as that of a shower enclosure, where the glass is handled, cleaned, opened and closed daily.

Not just any tempered glass is valid for any application: the standard that specifically regulates thermal safety tempered glass in buildings—and therefore in shower enclosures, glass doors or enclosures—is EN 12150. At NOLUXA, as distributors of IMEX and GME, the glass that is mounted in shower enclosures corresponds to this category of safety tempered glass, not untreated annealed glass.

How tempered glass breaks and why it matters

The most important practical difference between tempered glass and normal annealed glass is not whether it can break – any glass can do so in the event of a sufficiently strong blow or a specific defect – but rather how it breaks. Annealed glass, when fractured, tends to generate large fragments with sharp edges, with the real capacity to cause deep cuts. A tempered glass, due to the internal stresses that have been induced during the tempering process, fragments in a very different way: it breaks up into a large number of small pieces, with blunt edges and hardly any cutting capacity. It is precisely this breaking behaviour that European regulations define and require verification by testing, and it is the reason why tempered glass is considered "safety glass".

This table summarizes the general and verifiable behaviour of each type of glass when broken; It does not replace a laboratory test nor does it indicate impact resistance figures, which depend on the thickness, the size of the panel and the specific conditions of each standardised test.

What does EN 12150 require?

EN 12150 is the harmonized European standard regulating "thermally tempered soda-lime silicate safety glass" for use in buildings. It is divided into two parts with different and complementary functions:

• EN 12150-1: establishes the definition and description requirements of the product, as well as the test methods that tempered glass must pass, including the fragmentation test (which verifies that breakage occurs in the pattern of small, blunt pieces described above) and other quality tests related to flatness, the manufacturing process and dimensional tolerances.
• EN 12150-2: regulates the evaluation of product conformity, that is, the procedure by which a manufacturer certifies that its tempered glass consistently meets the requirements defined in the first part of the standard over time, not only in a specific test.

Overall, the standard does not certify a specific resistance figure that you can freely compare between manufacturers: it certifies that the glass has been manufactured with a controlled tempering process, that it has passed the fragmentation and quality tests defined by the standard, and that there is a production control system that supports this conformity on an ongoing basis. It is, in that sense, a guarantee of process and behaviour at breakage, not a promise of unlimited resistance against any impact.

The marking the glass must carry

That a glass is tempered and complies with the EN 12150 standard is not something that can be verified with the naked eye by looking at the panel mounted in the shower enclosure: it is not visible to the eye whether a glass has been tempered correctly or not. That is why the regulations themselves require that the glass bear a permanent marking, engraved on the glass itself (usually by acid or laser etching in a corner of the panel), which must remain legible throughout the useful life of the product.

This marking, in general, must identify at least:

CE marking and the Construction Products Regulation

Tempered safety glass for buildings is one of the construction products subject to the European CE marking framework, regulated at the community level by the Construction Products Regulation. In practice, this means that the manufacturer who puts tempered glass on the market in accordance with the EN 12150 standard must be able to prove, through the corresponding declaration of performance, that the product meets the harmonized requirements applicable to that type of glass.

For those who buy a shower enclosure, it is not necessary to understand the administrative detail of this regulation: the relevant thing is that there is a European regulatory framework, not a commercial label invented by each manufacturer, and that this framework is what gives meaning to the marking engraved on the glass. The CE marking and the reference to EN 12150 are not an ornament or a marketing phrase: they are the way in which the manufacturer assumes, in writing and in a traceable way, responsibility for the product it has manufactured.

Why these details matter

It is common that, when purchasing a shower enclosure, attention goes to the profile design, the type of opening or the metal finish, and that the glass is taken for granted. It is understandable: a tempered glass panel and an annealed one can appear identical to the naked eye, with the same brightness and the same transparency. The difference only becomes apparent if the glass breaks, and by then it is too late to choose. That's why it's a good idea to ask or check it before, not after:

• Because the bathroom is a domestic space for daily use, with children, elderly people or simply in a hurry in the morning, where an accidental knock against the glass is not an unlikely scenario.
• Because the difference between blunt fragments and sharp pieces is literally the difference between a scare and a serious injury.
• Because the engraved marking is the only objective way to verify, after installation, that the glass really corresponds to what was paid for.
• Because, in the event of any incident or claim, having identifiable and certified glass facilitates management with the manufacturer or distributor.

At NOLUXA, when distributing shower enclosures from IMEX and GME, tempered safety glass in accordance with EN 12150 is part of the product specification, not an optional extra. It is not something you have to negotiate or ask for separately: it is the foundation on which any shower enclosure that deserves to be called that is built.