The reason for doing so is understandable: a fire-rated glazed door provides visibility into a corridor or sensitive room, and you may want to add frosted or privacy film to protect confidentiality. However, this seemingly minor alteration can call the compliance of the entire assembly into question. Here are the key points to assess before making a decision.
What compliance means for a fire-rated door
A fire-rated door is not simply an assembly of components: it is a system certified as a whole. Its fire-resistance classification—expressed as E (integrity only) or EI (integrity and thermal insulation), under EN 1634-1 for fire-resistance testing of doors and shutters—is assigned to a specific assembly comprising:
- The frame or door surround
- The door leaf or panel
- The integrated glazing, with defined type and dimensions
- The hardware, including the door closer, lock and hinges
- Intumescent seals
- Any component fitted at the factory, where applicable
The classification results from a laboratory test conducted on a specific configuration. It is formalised in a test report confirming the performance of that particular assembly. If the door is subsequently modified, the report holder—generally the door manufacturer or its authorised representative—is the only party able to determine, through its technical documentation or an additional assessment carried out under the applicable standards, whether the classification remains valid.
Privacy film in this configuration: an alteration that must be assessed
Decorative or privacy film is not neutral from a fire-resistance perspective. It can affect the assembly in several ways:
- Change in the glazing's thermal behaviour: film can alter heat transfer and the temperature profile at the glass surface, which may affect thermal stresses during a fire.
- Risk of delamination under intense heat: heat-sensitive adhesives may break down, generate smoke or interact with the glazing's properties.
- Lack of test data: unless the film was specifically included in the fire-resistance test, there is no certified data on its behaviour in real conditions.
Adding an unvalidated film to the glazing in a fire-rated door may invalidate the assembly's fire-resistance classification. Only the test report holder's documentation—or an additional assessment carried out under the applicable standards—can establish whether this is the case.
What manufacturers and standards say
Several manufacturers of fire-rated doors and fire-resistant glazing state in their technical data sheets that adding any film or coating to the glazing without their written approval may invalidate the test report. US UL guidance on fire-rated doors (source: UL—Fire Rated Doors Guide: https://www.ul.com/thecodeauthority/knowledge/ul-fire-rated-doors-guide) takes a similar approach, although the US framework differs from the European system based on EN 1634-1.
In France, regulations applicable to public-access buildings (ERP) require compartmentation elements—including fire-rated door sets—to comply when the building is commissioned and to remain compliant throughout their service life. An undocumented modification may expose the operator to compliance requirements imposed by the relevant authorities.
What should you do if privacy is required?
Several approaches can meet privacy requirements without altering glazing whose classification is at stake:
- Consult the door manufacturer: some manufacturers offer factory-treated glass (etched, frosted or printed) integrated at the design stage and covered by the test report.
- Look for film assessed for fire-resistant glazing: some products have been tested jointly with fire-resistant ceramic glazing. These references are rare and require case-by-case documented approval from the test report holder.
- Replace the glazing with glazing that incorporates privacy at the manufacturing stage—provided the new glazing is listed in the existing test report or covered by an additional assessment.
- Use a solution outside the glazing: a partition, blind, curtain or signage installed on the corridor side without touching the certified door.
Steps to take before installation
If film installation is still being considered, carry out these checks first:
- Obtain the exact door and glazing references, together with the test report or performance assessment number.
- Contact the test report holder (the door manufacturer or its authorised representative).
- Obtain a written technical opinion specifying whether the proposed film is compatible and under what conditions.
- Check the situation with the building's fire-safety manager and, where applicable, the inspection body.
For more information about safety glass and classification differences, read the article What Is Safety Glass? Composition and Types. For glazing without fire-resistance requirements, E-FILM switchable privacy film may be a suitable option. However, this solution is not suitable for a door whose classification covers the glazing unless the test report holder has given specific approval.