EI1 and EI2 are fire resistance classifications that tell you how long a door will contain both fire and heat — in minutes — while limiting temperature rise on the unexposed side. The letter E indicates integrity (the door does not burn through or crack), while I indicates insulation (the unexposed side does not overheat). EI1 applies the stricter insulation criterion; EI2 permits a higher temperature rise on the unexposed side. Which class applies to your project depends on the building type, the size of the fire compartment and the applicable national building regulations. The W criterion — which limits radiant heat transfer rather than requiring full insulation — is the Dutch standard baseline and is discussed further below.
The sections below unpack each aspect of fire resistance classification in detail, from how the numbers are tested to what a complete fire door specification must include.
What do the numbers in fire resistance classifications such as EI2-60 or EW 90 actually mean?
The numbers in fire resistance classifications represent the minimum duration, in minutes, that a fire-rated door must maintain its classified performance under standardised fire test conditions. A classification of EI2-60 means 60 minutes of protection under the less strict insulation criterion; EI1-90 means 90 minutes under the stricter insulation criterion; EW 90 means 90 minutes of integrity combined with radiation reduction. The longer the duration, the more time occupants, emergency services and adjacent compartments have to respond to a fire.
These durations are not arbitrary. They are derived from the standard fire curve defined in EN 1363-1, which simulates the temperature development of a real structural fire. During a test, a door assembly is exposed to that curve for the full classification period. The door must remain intact and meet the relevant thermal criterion throughout. If it fails at minute 55 during a 60-minute test, it does not receive a 60-minute certification — it receives nothing above the last threshold it passed.
For project planners and facilities managers, the practical implication is straightforward. A door rated EI2-60 gives the fire brigade twice the intervention window of a door rated to 30 minutes. In a logistics warehouse where a fire can spread rapidly across large floor areas, that difference is not marginal. It directly affects evacuation time, structural damage and the insurance position of the building owner.
It is also worth noting that fire resistance ratings apply to the complete door assembly — the leaf, the frame, the glazing if present and the hardware. A door leaf that passes EI1-90 testing but is installed in an uncertified frame does not carry EI1-90 classification in practice. The certification covers the system, not the component.
What is the difference between E, W and I in fire door classification?
In fire door classification under EN 13501-2, E stands for integrity, W stands for radiation reduction and I stands for insulation. These are distinct performance criteria that can be combined in different ways depending on the application.
E measures whether the door prevents flames and hot gases from passing through gaps or cracks. W measures whether the door limits radiant heat transfer through its surface — this is the Dutch standard baseline criterion for industrial fire doors. An EW classification therefore combines integrity with radiation reduction, but does not require the door to fully limit temperature rise on the unexposed side.
An EI classification is stricter in the insulation dimension. Here it is essential to distinguish between two sub-criteria: EI1 applies the stricter insulation threshold, limiting temperature rise on the unexposed side to a lower level; EI2 permits a higher temperature rise on the unexposed side and is therefore the less strict insulation criterion. Never write “EI” alone without specifying whether it is EI1 or EI2 — the two have meaningfully different performance levels and are not interchangeable in a specification.
This distinction matters practically. In a corridor used as an escape route, a door that maintains integrity but radiates intense heat through its surface can still injure or disorient evacuees. For occupied buildings, healthcare facilities and any route where people need to pass close to the door during evacuation, the I criterion adds an important layer of protection beyond what W alone provides. Which criterion is required for a specific project depends on the fire safety calculation for that building — this is a determination for a qualified fire safety engineer or the local building authority, not a general rule that can be read from the building type alone.
Never use EW and EI interchangeably in a specification. They are distinct classifications with different performance thresholds. Substituting one for the other in a building permit or insurance document is a compliance error that can invalidate certification.
Which fire resistance class is required for which building type?
The required fire resistance class depends on the building’s risk category, the size of the fire compartment and the national building regulations that apply. In the Netherlands, the BBL (Besluit Bouwwerken Leefomgeving, formerly Bouwbesluit) sets the absolute minimum requirement — it does not prescribe a single fixed classification for a given building type. The Dutch standard baseline for industrial fire doors is EW60, meaning integrity combined with radiation reduction for 60 minutes. EI2-60 is a common and fully valid alternative, not an exception.
A heavier classification than the baseline may be required for several distinct reasons: the project deviates from standard building regulations and a heavier classification is therefore mandated; a sector-specific regulation applies, such as PGS15 for chemical storage; the client or principal sets a stricter above-statutory requirement; or the insurer requires a heavier classification. None of these are changes to the BBL itself — they are project-specific circumstances that affect which classification is appropriate. The correct classification for any given project is determined by a fire safety engineer or the local authority on the basis of a project-specific calculation.
Across Europe, national annexes to the Eurocodes and country-specific building regulations add further requirements. Germany, France, Switzerland and Austria all have supplementary certification requirements beyond the base EN 1634-1 test. A door certified to EN 1634-1 alone may not automatically satisfy the local authority in those markets without additional national testing. This is a common source of specification errors when sourcing doors internationally.
The safest approach is to confirm the required class with the project’s fire safety engineer or the local building authority before specifying a product. The classification is a legal minimum, not a recommendation. Getting it wrong creates liability that sits with the specifier, the installer and ultimately the building owner.
How is a fire door’s EI rating tested and certified?
A fire door’s fire resistance rating is determined through a standardised furnace test conducted according to EN 1634-1. The complete door assembly, including the frame and all hardware, is mounted in a test furnace and exposed to the EN 1363-1 standard fire curve. Independent testing laboratories monitor integrity, radiation and insulation continuously throughout the test. If the assembly meets the relevant criteria for the full classification period, it receives a test report and can be classified accordingly under EN 13501-2.
Certification goes a step further than testing. For industrial fire doors, two CE marking standards apply simultaneously: EN 16034, which covers fire-resisting and smoke control door sets, and EN 13241, which applies to all industrial doors regardless of fire rating. Both are mandatory and must not be treated as interchangeable or as alternatives to one another. CE marking requires not only the test report but also a documented factory production control system ensuring that every door leaving the production line matches the tested configuration. Third-party audits verify this on an ongoing basis.
The result is a classification report that specifies exactly what was tested: the door dimensions, the frame type, the glazing area if applicable, the hardware and any special configurations. This report is the document that building inspectors, fire safety engineers and insurers will ask for. A door without a traceable classification report, or one where the installed configuration deviates from the tested configuration, cannot be considered certified regardless of what the product label says.
Metacon-Next fire-rated industrial doors comply with EN 1634-1 and carry EPD certification. All classification reports are published openly on the website, which means specifiers can verify the documentation without needing to request it separately.
Can a fire door lose its fire resistance classification after installation?
Yes. A fire door can lose its effective fire resistance classification after installation if it is modified, damaged or maintained incorrectly. The classification applies to the door assembly as it was tested. Any deviation from the tested configuration — including changes to hardware, the addition of non-certified glazing, alterations to the frame or the use of uncertified replacement seals — can invalidate the classification even if the door looks intact.
The most common causes of classification loss in practice are:
- Replacing original hardware (hinges, closers, locks) with non-equivalent components that were not part of the tested assembly
- Drilling additional holes in the door leaf for cable management or signage without manufacturer approval
- Allowing intumescent seals to deteriorate without replacement, which compromises the integrity criterion
- Holding the door open with a wedge or prop, which damages the closing mechanism over time
- Repainting the door with a non-certified coating that alters the thermal behaviour of the leaf
For facilities managers, this means that a fire door requires an ongoing maintenance programme, not just a one-time installation check. Most national building regulations require periodic inspection of fire doors as part of the building’s fire safety management plan. The frequency and scope of those inspections should be documented and traceable, particularly for buildings subject to insurer audits.
When sourcing doors, clear installation instructions and maintenance documentation from the manufacturer are not optional extras. They are part of what keeps the classification valid over the building’s service life.
What should a fire door specification include beyond the fire resistance class?
A complete fire door specification must go beyond stating the fire resistance class. It should include the door type and opening dimensions, the tested configuration reference from the classification report, the applicable standard, hardware requirements, installation tolerances and any country-specific certification requirements. Without these elements, a specification leaves room for substitution with a product that meets the classification on paper but not in the intended application.
The following elements belong in every fire door specification for an industrial or commercial project:
- Classification reference: The exact fire resistance class — specifying EI1 or EI2 explicitly where the I criterion applies, or EW where radiation reduction is the relevant criterion — together with the duration in minutes and the standard under which it was tested (EN 1634-1), with results classified per EN 13501-2
- Opening dimensions: Clear width, clear height and structural opening dimensions, especially for large industrial openings that exceed standard product ranges
- Door type: Whether the application requires a roller shutter, sectional door, sliding door or hinged door set, as each type has different tested configurations
- Hardware specification: Certified closers, locks, hinges and seals must be specified by reference to the tested assembly, not as generic components
- CE marking: For industrial fire doors, confirm that both EN 16034 (fire/smoke resisting closing element) and EN 13241 (industrial door) CE markings are in place — both apply simultaneously and neither replaces the other
- National certification: For projects in Germany, France, Austria or Switzerland, specify the additional national approval required alongside the EN classification
- EPD requirement: For BREEAM or LEED-rated projects, confirm whether an Environmental Product Declaration is required and whether the manufacturer can supply one
- Documentation package: Classification report, CE declaration of performance, installation manual and maintenance schedule should all be listed as deliverables
Specifying only the fire resistance class leaves the door selection open to interpretation by contractors who may prioritise cost over compliance. A tightly written specification that references the tested configuration removes that ambiguity and protects the specifier if the installation is challenged during inspection.
For projects where opening sizes, building function or international certification requirements create complexity, working with a manufacturer that produces its own doors and publishes its full documentation openly is the most defensible position. Metacon-Next manufactures fire-rated industrial doors across a range of EI1, EI2 and EW classifications, including for non-standard openings, and makes all certification and EPD documentation publicly available. Products are supplied through a network of certified dealers and installers, so both the product and the installation are covered. If you are working on a specification now, you can request a quotation or contact the team directly for technical support.
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