Fire rating of insulation – what you need to know

Fire rating of insulation – what you need to know

Fire safety and regulations are an incredibly important consideration in residential and non-residential construction projects. It’s vital that regulations are understood and adhered to in order to ensure buildings are safe and sustainable. 

In the construction industry, insulation materials are largely regulated and classified against the BS EN 13051-1 standard “Fire classification of construction products and building elements”. 

In this post, we’ll get into the specifics of the BS EN 13051-1 and what it means. 


What are the fire ratings of insulation?

The BS EN 13051-1 standard for the reaction to fire of insulation material consists of three ratings, in three areas. 



The Euroclass rating was introduced to harmonise standards across the EU (we still use this classification system in the UK despite Brexit) and categorises products into one of seven classes depending on their reaction to fire, running from A1 (best performance) to F (worst performance). 

Classification Definition Description
A1 Non-combustible No contribution to fire
A2 Limited combustibility Very limited contribution to fire
B Combustible Limited contribution to fire
C Minor contribution to fire
D Medium contribution to fire
E High contribution to fire
F Easily flammable


Smoke emission

The second part of the rating refers to smoke emissions during combustion, and is divided into 3 levels, with an “S” prefix.


Classification Level Description
Smoke emission during combustion S1 Quantity/speed of emission absent or weak
S2 Quantity/speed of emission of average intensity
S3 Quantity/speed of emission of high intensity


Flaming droplets

The final classification relates to the production of flaming droplets or particles during combustion within the first 10 minutes of exposure to fire. 


Classification Level Description
Production of flaming droplets during combustion D0 No dripping
D1 Low dripping
D2  High dripping


These ratings are then combined to give a coded rating for the material, for example: 

A1 – s1,d0 

Would be a material with no combustibility, little to no emission of smoke during combustion, and no production of flaming droplets. 



Would be a combustible material with average smoke emission and low production of flaming droplets. 


How are fire rating requirements determined?

The minimum fire rating required for construction materials depends on the type and use. 

In dwellings, surface linings of walls and ceilings should meet the following classifications. 


Location Required classification
Small rooms of maximum internal floor area of 4m2

Garages of maximum internal floor area of 40m2 (as part of a dwelling)

Other rooms (including garages) 

Circulation spaces within a dwelling

Other circulation spaces (including common areas of blocks of flats) B-s3,d2


For buildings other than dwellings, the required classifications are as follows.

Location Required classification
Small rooms of maximum internal floor area:

  1. 4m2 in residential accommodation
  2. 30m2 in non-residential accommodation 
Other rooms (including garages) C-s3,d2
Other circulation spaces B-s3,d2


Changes to building regulations

Since the Grenfell Tower disaster on 14 June 2017, and the subsequent enquiry, the government have proposed a ban on the use of combustible materials only in high-rise residential buildings. This has been criticised as it only applies to residential buildings over 18m in height, leaving thousands of other residential buildings, and other high-risk buildings such as schools, hotels, care homes and hospitals at risk of being cladded with materials with the same level of combustibility as the materials used on Grenfell Tower. Consultations and hearings are ongoing as the inquiry continues.

Elmelin are working with the construction industry to design and develop specialised, high performance A1 rated mica-based insulation solutions to ensure the greatest possible safety whilst maintaining cost-effectiveness. If you’d like to find out more about our solutions for construction, get in touch