Understanding E, EW, EI, and FD ratings for fire-resistant internal doors

If you're an architect, contractor, or interior designer in London, you're likely familiar with the UK's strict fire regulations for both commercial and residential properties. If you're new to this, it's crucial to understand the different fire resistance ratings (E, EW, EI, and FD) when sourcing internal doors. This post will help you navigate the complexities and explain the distinctions to ensure you meet regulatory requirements.

Andy Howard

Understanding E, EW, and EI ratings for fire-resistant internal doors

When sourcing fire-resistant internal doors for a high-end project you’ll be looking to combine style and safety - that’s where Envo can help. We work with UK based fire testing, inspection and certification businesses to ensure we can offer our clients a suitable solution whether you’re looking for a contemporary steel glazed door or a classic timber door. The following outlines the fire classifications for steel, glass, aluminium, and timber doors.

E, EW, and EI ratings relate to materials that conduct heat, such as steel, glass, and aluminium as well as non-conductive materials such as timber. The three fire classifications are combined with a time in minutes which confirms the product’s performance under test conditions.

E - Integrity Only

An Integrity Only (or Integrity) fire rating refers to the length of time the door and its components can prevent the passage of flames and hot gases from the heated side of the door to the non-heated side. However, this rating offers no protection against heat. The E rating is followed by a number indicating the amount of minutes the product will sustain protection for.

Examples include:
E30 (30/0) = 30 Minutes
E60 (60/0) = 60 Minutes
E90 (90/0) = 90 Minutes

fire rated internal doors Integrity only E rating for steel glazed doors

EW - Limited Heat Irradiation

Limited Heat Irradiation, also referred to as Radiation Control, maintains the performance of Integrity Only (E) meaning it prevents the spread of flames and hot gasses, whilst also preventing some of the heat from transferring from the heated side of the door to the non-heated side. EW keeps the amount of radiant heat to below 15kW/m2. The EW rating is followed by a number indicating the amount of minutes the product will sustain protection for.

Examples include:
EW30 (30/0) = 30 Minutes
EW60 (60/0) = 60 Minutes
EW90 (90/0) = 90 Minutes

limited heat irradiation / radiation control EW for fire rated internal doors including steel glazed doors and screens

EI - Insulation

Insulation or Integrity & Insulation offers the highest level of protection from fire. Offering the same performance as Integrity (E), Insulation (EI) also prevents any heat transferring from the heated side to the non-heated side. ‘EI’ will be followed by the number of minutes it provides fire resistance in terms of both Integrity and Insulation for example EI90. This rating can also be recorded with different values for Integrity and Insulation, an example would be EI90/60 meaning the doorset has been certified 90 minutes for Integrity and 60 minutes for Insulation.

Examples include:
EI30 (30/30) = 30 Minutes (30 mins Integrity and Insulation)
EI60 (60/60) = 60 Minutes (60 mins Integrity and Insulation)
EI90 (90/90) = 90 Minutes (90 mins Integrity and Insulation)

Insulation and Integrity - EI fire resistant internal doors

FD fire-rated doors

An FD rating is a grade established by the British Woodworking Federation (BWF) to ensure that timber fire doors are compliant. This rating is often used as general terminology for all required fire-rated doors on an architect’s door schedule.

The FD rating system monitors:

Integrity failure: when cracks develop on the door due to the pressure of the fire, which can allow hot gases and smoke to pass through.
Stability failure: when a door starts to collapse due to the pressure of the surrounding conditions.

The ratings are stated as FD followed by the number of minutes, for example, FD30 offers 30 minutes of protection against fire.

The most commonly specified integrity levels are:
FD30 – 30 minutes
FD60 – 60 minutes
FD90 – 90 minutes
FD120 – 120 minutes

FD ratings can also include the ‘S’ suffix, for example, FD30S. This indicates that the door is both a fire and smoke controlled door.

If you’re specifying internal fire-rated doors on your next project, feel free to speak to a member of the Envo team for more information: info@envo.co.uk / +44 (0) 208 253 9342

Discover our fire-rated options here:

Envo Steel – E30, E60, EW30 and EW60 steel glazed doors

Envo Steel - EW30 and EW60 steel glazed screens

Envo Flush – FD30 jib doors

Envo Slide - FD30 pocket doors