A change of building use triggers new fire safety requirements when the new function places higher demands on passive fire protection than the original design anticipated. Under Dutch building regulations, the Besluit bouwwerken leefomgeving (Bbl) applies the requirements of the new use category to the relevant parts of the building, which often means reassessing fire compartmentation, escape route protection, and fire door classifications. The sections below address the most common questions architects face when a conversion project reaches the fire safety specification stage.
What counts as a change of use under Dutch building regulations?
A change of use occurs when a building or part of a building is assigned a different function category under the Bbl than the one for which it was originally permitted. This includes conversions from storage to production, from office to healthcare, from single-occupancy industrial to multi-tenant logistics, or from any use class to one that introduces sleeping functions or higher occupancy loads. The trigger is the new function, not the physical alterations themselves.
The Bbl distinguishes between user functions such as industrial, office, healthcare, residential, and assembly. Each function carries its own set of performance requirements. When the actual use shifts from one category to another, the building must be assessed against the requirements that apply to the new category, at least for the affected parts of the structure. In practice, this assessment is carried out by a fire safety engineer or advisor as part of the permit application, and it determines which existing elements are compliant, which require upgrading, and which can be accepted under equivalence reasoning.
A partial change of use — for example converting one floor of a warehouse into office space — can trigger requirements for the boundary between the two functions even if the rest of the building remains unchanged. The boundary itself becomes a fire-rated separation that must meet the performance level appropriate to both adjacent functions.
Which fire safety requirements are reassessed when a building’s use changes?
When a building’s use changes, the requirements that are reassessed include fire compartmentation boundaries, maximum compartment sizes, escape route protection, smoke control provisions, and the fire resistance classification of separating elements, including doors. The starting point is always the Bbl requirements for the new user function, applied to the building as it exists.
For architects, the most consequential reassessment typically involves fire compartmentation. The Bbl sets maximum compartment sizes that differ by function: an industrial building may accommodate larger compartments than a healthcare facility, for instance. If the new use requires smaller compartments, new separating walls and fire-rated openings may need to be introduced within the existing shell.
Escape route protection is another area that frequently changes. A function with higher occupancy, or with occupants who cannot self-evacuate, imposes stricter requirements on corridor widths, door swing direction, and the fire resistance of enclosing elements. These requirements cascade directly into door specifications.
It is important to note that the Bbl sets only the absolute minimum performance levels. Project-specific fire safety calculations, sector regulations such as PGS15 for hazardous substances storage, and insurer requirements can all impose stricter standards than the Bbl baseline. A use change is therefore an opportunity to review the entire fire strategy, not simply to check boxes against the new function category.
Does a change of use always require upgrading fire-rated doors?
Not always. Whether existing fire-rated doors need to be upgraded depends on whether they already meet the classification required by the new use, and whether the fire compartmentation boundaries they serve remain in the same locations. If the existing doors carry a sufficient classification and are correctly certified, they may remain in place. If the new use requires a higher classification, a different door type, or repositioned compartment boundaries, replacement or addition is necessary.
An existing fire door that was installed and certified under the previous use is not automatically invalid. What matters is whether its documented classification matches the requirement that now applies to that opening. This is where complete technical documentation becomes critical. A door without a traceable classification report, CE declaration of performance, or installation record cannot be relied upon in a permit application or fire safety review, regardless of its physical condition.
In practice, many conversion projects encounter doors that were installed without full documentation, or whose certificates have been lost over the years. In those cases, the architect or fire safety advisor must either obtain retrospective documentation from the original manufacturer or specify replacement doors that can be fully documented from the outset. Metacon-Next’s fire-rated door range is supplied with classification reports, CE declarations of performance, and EPDs as standard, which simplifies this process considerably for new specifications.
What is the difference between EW, EI1, and EI2 for a conversion project?
EW, EI1, and EI2 are fire resistance classifications defined under EN 13501-2, and they represent different levels of performance that a fire-rated door must demonstrate during a standardised fire test. Understanding the distinction is essential when specifying doors for a conversion project.
EW: integrity and radiation reduction — the Dutch standard baseline
An EW-classified door provides integrity (E) — preventing flames and hot gases from passing through — and limits radiant heat transfer to the unexposed side (W). EW is the Dutch standard baseline criterion for fire-resistant industrial doors and is appropriate where the primary concern is containing fire spread. It does not, however, limit the temperature rise of the door surface itself to the same degree as an insulation-rated door. Whether EW is sufficient for a specific opening in a conversion project depends on the fire safety calculation for that building — this determination must come from a qualified fire safety engineer or the local authority, not from a general rule about building type.
EI1 and EI2: thermal insulation at different levels of strictness
Both EI1 and EI2 classifications combine integrity (E) with insulation (I), meaning the door also limits the temperature rise on the unexposed side. The two differ in how strictly that insulation criterion is applied:
- EI1 is the stricter insulation criterion: the temperature rise on the unexposed face is limited to a lower threshold.
- EI2 is the less strict insulation criterion: a higher temperature rise on the unexposed side is permitted while still meeting the classification.
For a conversion project, the choice between EW, EI1, and EI2 — and the required duration (for example 60 or 120 minutes) — depends on the fire safety calculation for the specific opening, not on a blanket assumption about the building type. An escape route that passes directly alongside a compartment boundary, or a separation adjacent to a function with vulnerable occupants, may require EI1 where EI2 or EW would be insufficient. This determination must always come from a project-specific analysis by a qualified fire safety engineer. When in doubt, consult Metacon-Next directly.
Architects specifying Metacon-Next products can verify which classification applies to each product in the published Efectis classification reports, which are available without needing to contact the manufacturer first.
How should an architect document fire door compliance after a use change?
After a use change, an architect should document fire door compliance by assembling a complete specification file for each fire-rated opening. This file must include the CE declaration of performance, the classification report from an accredited test body such as Efectis, the installation record confirming the door was installed in accordance with the conditions of the classification, and, where required for sustainability assessments, an Environmental Product Declaration (EPD). This documentation forms the basis for demonstrating compliance during permitting and any subsequent fire safety review.
The classification report is particularly important because it defines the exact conditions under which the door was tested, including wall construction, frame type, and hardware. A door is only compliant when installed in a configuration that matches or falls within the scope of that report. Deviations in wall thickness, frame anchoring, or glazing specifications can invalidate the classification even if the door leaf itself is correctly certified.
For conversion projects, the documentation challenge is often greater than for new construction, because existing openings may not match standard tested configurations. This makes it advisable to involve the door manufacturer early in the design process, before dimensions and wall constructions are fixed, so that the specified product can be confirmed as compliant with the actual installation conditions. Architects who work with Metacon-Next have access to full technical documentation — including CE declarations of performance, Efectis classification reports, and EPDs — at specification stage, which means the compliance file can be assembled before the order is placed rather than after.
Finally, the documentation should be retained as part of the building dossier for the lifetime of the building. A use change that is permitted today may itself be reassessed in the future, and the ability to demonstrate what was installed, to what standard, and under what conditions is a professional obligation that extends well beyond the completion of the project. For questions about specific product documentation, or to request a quotation for a conversion project, Metacon-Next’s dealer network can be reached through the contact page.