Fire classification system for fire curtains
Read Time: 4 Minutes
Fire safety is one of the most critical considerations in any building project, and fire curtains play a vital role in passive fire protection. To ensure compliance and safety, fire-rated products – including fire curtains, fire doors, and fire-resistant glass, are classified using a standardised fire rating system.
This system provides E (Integrity), EW (Integrity & Radiation), and EI (Integrity & Insulation) ratings, helping architects, contractors, and building managers select the right fire protection solutions.
In this guide, we explain how fire curtain ratings are determined, their role in fire safety, and why third-party certified, high-performance solutions, such as our Adexon fire and smoke curtains – are essential for compliance.
E (Integrity) - Preventing flame spread
The most common fire classification is the E or Integrity rating. This rating measures a fire curtain’s ability to withstand fire exposure on one side without allowing the flames to pass through to the unexposed side.
Integrity is measured by using a furnace to raise the temperature on one side of the product to over 1000°C, following a standardised heating regime (such as that defined in BS EN 1363-1). Three criteria are used to assess the passing of the flame through the barrier:
- Cracks or openings in excess of a given dimension appear in the product.
- A cotton pad on the unexposed side ignites.
- Sustained flaming occurs on the unexposed side.
The test ends when any of these events are observed. Alternatively, a manufacturer can choose to stop the test prior to the flames passing through the product if the desired performance level has been reached. The result is a rating of EXXX, where XXX is the duration of the test in minutes.
Fire Safety Tip: While an E-rated fire curtain prevents fire from spreading, it does not block heat transfer, making it less effective for high-risk areas.
EW (Integrity and Radiation) - Limiting heat transmission
The EW rating includes integrity (flame containment) and radiation control, ensuring reduced heat transfer. This can be important in specific areas, as this prevents extreme heat exposure on escape routes, providing safer evacuation conditions.
During the test, two heat flux meters are placed a distance of 1m from the unexposed side of the product, to measure the thermal energy radiated from the product across a specific area over a given time. One meter is aligned with the centre of the product under test, to measure an average value, while the other is placed to measure what is likely to be the maximum heat flux.
The test is stopped when the integrity fails, or when the measured heat flux exceeds 15 kW/m2 (whichever occurs first).
Best For: High-traffic areas where fire curtain heat reduction is necessary for occupant safety.
EI (Integrity and Insulation) - Maximum fire protection
The EI rating is considered as the highest classification level for fire curtains. In addition to the fire integrity described previously, it also assesses the product’s ability to resist the conduction of heat through the material to the unexposed side. This is desirable as it protects anyone standing on the unexposed side from the fire’s heat, and stops any nearby materials from igniting and so spreading the flames.
The insulation rating is the time taken for the unexposed surface of the product to reach a temperature of 140°C above the mean initial temperature before the test began. The test is stopped when this criterion is reached or when the integrity fails (whichever occurs first).
Ideal For: High-risk buildings where fire containment and thermal protection are both required.
Be sure, be safe, don’t be sorry
To excel in health and safety, for insurance purposes, and to be sure your building can withstand a disaster, the highest classification can make all the difference for your peace of mind.
Here at Adexon, we test to the highest standards and insist on UKAS or equivalent third-party certification and CE Marking, to ensure our life-safety products perform in the worst circumstances. We believe that you should insist on these criteria too. Whilst there are minimum requirements in building regulations, superior quality products are always advisable. Fires are unforgiving.
If you want to know more about our excellent fire resistant products and whether they can be used for your building project, please get in touch.
This article was written in November 2022 and updated in February 2025 by the team at Adexon Fire & Smoke.