Safety glass in accordance with NEN 3569: when is it compulsory?

A NEN standard does not automatically constitute legislation. The Building and Living Environment Decree (Bbl) refers directly to NEN 2608 for glass structures. This standard sets out requirements regarding the reliability of glass structures and the consequences should the glass fail.

The edition of NEN 2608 that is legally designated is set out in Annex II of the Environment Regulation. A newly published version of the standard is not automatically the legally designated version. When undertaking a project, you should also take contractual agreements into account. Further information on this can be found in the IPLO’s explanation of references to standards.

NEN 3569 provides a practical approach for common situations to demonstrate that the risk of physical injury from breaking glass is adequately mitigated. If NEN 3569 is not used, or if a structure falls outside its scope, the safety of the glazing structure must be demonstrated using alternative evidence. This can be done, for example, by means of a project-specific risk analysis in accordance with NEN 2608.

Furthermore, NEN 3569 may be contractually binding if the standard is explicitly included in a specification, contract or confirmation of order. The practical conclusion is therefore that, in a high-risk location, ordinary glass cannot be chosen without justification.

NEN 3569:2018 applies to flat glass installed vertically and fixed in a continuous linear pattern, which is used as a construction product in a building or structure. All clear openings of the pane must be greater than 150 mm. The standard does not apply to glass that is accessible only during maintenance or repair work.

Glass is considered accessible if a person can reach the pane from a horizontal distance of no more than 850 mm. If there is a fixed structural feature on the impact side, at least 700 mm high, which prevents anyone from getting within 850 mm of the glass, then the pane may be regarded as inaccessible for the purposes of this assessment.

The fact that a window pane is not accessible in accordance with NEN 3569 does not automatically mean that no other safety requirements apply. For example, in the case of a difference in height, roof glazing, a glass balustrade or a non-standard mounting arrangement, an additional structural assessment may be required.

In the case of a fixed window, a glass wall or a standard operable section, the general rule is that the accessible side of the opening must be designed to minimise the risk of injury where the lower edge is no more than 850 mm above the adjacent floor.

The assessment applies to the inner and outer panes separately. For example, a low-level window on the ground floor may be accessible from both a room and a terrace. In such cases, with insulating glass, both the inner and outer panes may need to have injury-limiting breakage behaviour.

For a door assembly, the high-risk area extends up to 1,400 mm above the floor. A door assembly comprises the door, the associated frame and the relevant glazed sections immediately surrounding the opening.

A glass panel situated within 300 mm of the door opening is regarded as a side light. On the door itself, both sides are regarded as impact sides. In the case of a side light, an assessment must be made for each side as to whether the glass is accessible; a side that can be demonstrated to be inaccessible may be exempt from the injury safety requirement.

Along access routes, a height of 1,400 mm may also apply to accessible glazing. Examples include communal corridors, galleries and other routes used by people to move through a building. The intended use is an important factor in this regard.

In the explanatory notes to NEN 3569:2018, the separate requirement for access roads does not apply to the non-communal part of a residential or accommodation facility, nor to an industrial facility. However, the general rule for low-pane glazing and the rules for door constructions may still apply in such cases. Cases of doubt should therefore be assessed on a project-by-project basis.

An additional assessment applies to rotating parts where the part opens towards the impact side and, when closed, is accessible from only one side. If the lower edge is below 700 mm, then, according to the table in NEN 3569:2018, both sides must be designed to minimise the risk of injury. From 700 mm upwards, in this specific situation, only the accessible side is required.

This rule does not stand alone. The overall height, the intended use and the accessibility of the glass also remain part of the assessment.

NEN 3569 examines the fracture behaviour of the glass. Classification is carried out in accordance with NEN-EN 12600. The structural assessment of load-bearing capacity and deflections is carried out separately in accordance with the edition of NEN 2608 applicable to the project. An injury-limiting classification therefore does not, in itself, determine the required glass thickness or composition.

The explanatory notes to NEN 3569:2018 specify the following as the minimum injury-mitigating classifications:

The examples are not intended as universal advice on glass. The required thickness and construction may need to be greater depending on the pane dimensions, wind load, fixing method, intended use or additional requirements regarding fall-through protection, fire resistance, sound insulation or burglary resistance. You should therefore always check the classification and product details on the CE mark and have the overall glass assembly assessed.

Both laminated and heat-strengthened glass can help to minimise injury, but their fracture behaviour differs.

Laminated safety glass consists of two or more sheets of glass with a film between them. If it breaks, most of the shards stick to the film and the glass surface holds together better. This is often desirable when an opening must not form immediately following a break.

Tempered safety glass If broken, it shatters into many small glass granules rather than large, sharp shards. This reduces the risk of serious cuts, but the pane usually falls out of the opening when broken.

Which type is most suitable depends on the application. Toughened glass may be appropriate for a door or partition wall. Where there is a potential risk of falling through, a calculated laminated structure is often the more obvious choice. Even in such cases, the entire structure must be assessed on a case-by-case basis.

The bottom edge of a fixed window is 600 mm above the floor. The inside is accessible and there is a terrace outside, right up against the façade. Both sides are impact-resistant. At insulating glass Therefore, in principle, both the inner and outer panes must be designed to minimise injury.

A garden door can be accessed from both sides. For the door construction, the risk zone extends up to 1,400 mm, and the door has two impact sides. Both sides must therefore be taken into account in the assessment.

A window pane is situated 200 mm from the door opening. This pane is regarded as a side light of the door assembly. The 1,400 mm limit therefore applies to this pane. An assessment is made for each side to determine whether the window pane is accessible.

A window pane starts 1,000 mm above the floor. For a standard, non-communal living space, this is above the general limit of 850 mm. On the side of a communal gallery, however, the 1,400 mm limit may still be relevant due to the access route, depending on the intended use and the specific circumstances.

With a glass balustrade, it is not only the prevention of injury that is important, but, above all, protection against falling through. Simply opting for standard laminated or toughened safety glass is therefore insufficient. The entire structure must be calculated in accordance with the applicable structural regulations.