Fire Resistance Classes E, EW and EI: Meaning, Differences and Requirements

Why Fire Resistance Classes Are Essential in Fire Protection

In the event of a fire, the available time often determines the outcome of the situation. Fire, smoke and high temperatures must be confined to a limited area for as long as possible so that people can leave the building safely and emergency services have sufficient time to respond.

To ensure that building components perform this task reliably, they are tested according to established European testing procedures. One of the key standards is EN 13501-2. It defines how walls, doors, glazing systems and other building elements are assessed and classified in the event of a fire.

The fire resistance classes E, EW and EI describe the specific protective performance of a building component. They indicate which requirements are fulfilled and for how long these properties have been demonstrated during a fire test. Understanding the differences helps architects, planners and building owners better understand fire protection requirements and plan construction projects safely.

What Do the Fire Resistance Classes E, EW and EI Mean?

The three letters represent different protection objectives in fire safety.

E – Integrity

Class E certifies a building component's ability to prevent the passage of flames and hot fire gases. During the tested period, no fire may spread to the opposite side.

W – Radiation Control

In addition to integrity, Class W limits thermal radiation. This prevents people or combustible materials on the non-fire side from being exposed to dangerous levels of radiant heat.

I – Insulation

Class I represents the highest level of protection. In addition to maintaining integrity, the building component must ensure that the temperature on the side away from the fire rises only within specified limits. This reduces heat transfer to adjacent areas.

In practice, the letters are combined with a time classification. Examples include E 30, EW 60 and EI 90. The number indicates the number of minutes for which the building component has demonstrated the required performance during a fire test.

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How Are Fire Resistance Classes Tested?

Classification is determined through standardized fire resistance tests. During testing, the building component is exposed to fire from one side according to the standard time-temperature curve (STTC).

Within a short period, temperatures inside the test furnace rise to well above 800 °C. Throughout the test, it is monitored whether the specified performance requirements are maintained.

The following criteria apply to each classification:

E

• No passage of flames

• No passage of hot fire gases

• No unacceptable openings or cracks

W

• Maximum thermal radiation of 15 kW/m² on the non-fire side

I

• Average temperature rise of no more than 140 °C

• Temperature rise at any individual measuring point of no more than 180 °C

If a building component meets these requirements for the specified test duration, it receives the corresponding classification.

For example, a building component classified as EI 90 provides integrity and insulation for at least 90 minutes.

What Does EI 60 Mean in Practice?

The fire resistance classification EI 60 means that a building component prevents the passage of fire and limits heat transfer to the opposite side for a minimum of 60 minutes.

In many fire tests, modern systems achieve performance durations that exceed the required minimum period. However, for regulatory approval purposes, only the officially tested and certified classification is relevant.

Why Is This Classification So Important?

Fire resistance classes are not only used to comply with legal requirements. They are an essential part of passive fire protection and help protect both human life and property.

The correct classification ensures that escape routes remain usable for longer periods, fire compartments remain effectively separated and fire cannot spread uncontrollably to other areas of a building.

Modern architecture in particular, with open floor plans and large glazed surfaces, requires carefully planned fire protection solutions that combine safety and transparency.

When Is EW 30 Used?

In several European countries, the fire resistance class EW 30 is used to limit thermal radiation in addition to maintaining integrity. This can provide additional protection for escape and rescue routes.

In Germany, however, this classification has only limited practical significance because it is rarely required by building regulations. Nevertheless, it is frequently referenced in connection with international projects and European standards.

Standards and Legal Framework

The classification of building components throughout Europe is based on the requirements of EN 13501-2. This standard defines how fire resistance classes are determined and designated.

In Germany, these requirements are implemented through the Model Building Code (MBO) and the respective state building regulations. These regulations contain the requirements for fire-retardant, highly fire-retardant and fire-resistant building components.

The fire resistance class required in practice always depends on the specific construction project and the applicable state regulations.

Typical requirements include:

• Stairwells and escape routes: often at least EI 30

• Separations between occupancy units or fire compartments: often EI 90 to EI 120

As requirements may vary between federal states, the required classification should be considered at an early stage of the planning process.

Differences at a Glance

The three fire resistance classes pursue different protection objectives and, to some extent, build upon one another.

In simplified terms:

• E prevents the spread of fire and smoke.

• EW provides additional protection against excessive thermal radiation.

• EI further limits heat transfer to the non-fire side.

The higher the requirements for life safety and property protection, the more frequently EI-class constructions are used.

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How Is the Appropriate Fire Resistance Class Selected?

The required classification always depends on the specific requirements of the building. Key factors include the building's use, the number of occupants and the requirements defined within the fire protection concept.

Typical applications include:

E Components

• Technical rooms

• Storage areas

• Partition walls without special thermal insulation requirements

EW Components

• Applications in countries where this classification is required by building regulations

• Areas with increased requirements for protection against thermal radiation

EI Components

• Escape and rescue routes

• Archives

• Laboratory areas

• Building sections with increased protection requirements

As a general rule, the higher the occupant density and the greater the potential damage risk, the higher the required fire resistance classification.

Important note: The planning and installation of fire-resistant glazing systems are regulated at state level in Germany. Therefore, requirements may vary from one federal state to another.

Practical Example: Fire-Resistant Glazing Between a Corridor and an Office

A common application is a full-height glazed partition separating an office area from a corridor.

In such situations, an EI 60 glazing system may be used. This ensures that the glazing remains intact for the tested fire resistance period while simultaneously limiting heat transfer.

The special fire protection interlayer within the glass reacts to heat exposure and forms an insulating barrier. As a result, the temperature on the non-fire side remains within the permitted limits.

The outcome: escape routes remain usable for longer periods and adjacent materials are protected from critical temperature increases.

Why Hydrogel Technology Is Used in Fire Protection

Many modern fire-resistant glazing systems are based on special hydrogel interlayers positioned between the glass panes.

In the event of a fire, the hydrogel reacts to the intense heat exposure. The water contained within the interlayer evaporates and absorbs energy from the system. At the same time, an opaque protective layer is formed, significantly reducing heat transfer.

This effect keeps the temperature on the side away from the fire considerably lower than it would be without a fire protection interlayer.

This technology has proven particularly effective in EI-rated glazing systems and enables transparent solutions with a high level of fire protection performance.

Fire-Resistant Glass Does More Than Protect Against Fire

Modern fire-resistant glazing systems often combine multiple functions and make an important contribution to overall building performance.

Depending on the glass construction, they can also provide the following properties:

Thermal Insulation

High-performance glass assemblies can achieve Ug-values of up to 0.5 W/(m²K), supporting energy-efficient building concepts.

Acoustic Insulation

Depending on the system, sound insulation ratings of up to 46 dB Rw are possible. This makes fire-resistant glazing suitable for office buildings, healthcare facilities and educational institutions.

High Light Transmission

Light transmission values of up to 86 percent ensure that interior spaces remain bright and open despite high safety requirements.

UV Resistance

Modern fire-resistant glazing is permanently UV-resistant and retains its optical properties over many years.

Daylight for Improved Indoor Comfort

High light transmission supports a pleasant indoor environment and can positively influence occupant well-being.

These properties are tested and verified according to recognized standards such as EN 673, EN 410 and EN ISO 717-1.

They demonstrate that modern fire-resistant glazing systems provide far more than fire resistance alone.

Sustainability and the Future of Modern Fire-Resistant Glazing

In addition to passive fire protection, sustainability and resource conservation are becoming increasingly important. Modern fire-resistant glazing systems make a valuable contribution in this regard, as they can combine multiple functions within a single building component.

Current systems are characterized by long service lives, recyclable components and a high level of durability. Depending on the construction, metal or timber frames can be recycled after dismantling. At the same time, multifunctional glazing systems reduce the need for additional building components and contribute to more efficient construction methods.

Another advantage lies in the combination of different performance characteristics. Modern fire-resistant glass not only provides protection against fire but can also offer acoustic insulation, thermal insulation and high light transmission. This creates real added value for planning, building operation and sustainability.

Understanding Safety and Planning Correctly

The fire resistance classes E, EW and EI are far more than technical abbreviations. They describe the protective performance of a building component in the event of a fire and indicate how long critical functions are maintained.

Selecting the correct fire resistance classification helps protect people, preserve property and comply with fire safety regulations. At the same time, it provides planning certainty for architects, specialist planners, building owners and authorities.

Anyone who understands the differences between E, EW and EI can better assess fire protection concepts and select the appropriate solution for a specific construction project.

Further technical information on tested fire protection systems in classes EI 30 to EI 120 can be found at ARDOREX® Fire-Resistant Glass.

Author: Arnold Glas Marketing Department