Combustible cladding is to be banned for all new schools, hospitals, care homes, student accommodation and residential buildings in England above 18m (60ft).
So what will the ban include, and what materials can be used?
Using the Euroclass EN13501-1 classification system, any major component within the cladding zone will have to be A2 or A1 rated. All other rated products from B to F will be not allowed. Below is a chart showing the classifications and the corresponding national standard.
Click below to view a animation explaining a compliant full wall build up.
Valcan offer non-combustible and limited combustibility solutions as follows:-
These are available in a huge range of finishes and effects, from wood effect, high gloss finishes, natural finishes, metallic and chromatics to stone and metal effects. All fully compliant and tested.
Why is Class 0 no longer suitable?
In the UK Building Regulations on fire safety (1991), the BS476 classification was introduced to determine the surface spread of flames for materials used in the construction of wall and ceiling linings. The classification was rated from 1 through to 4 – Class 1 being best performing and Class 4 being worst performing. Performance is measured on distance and speed of flame spread. The classification also has Class 0 which indicates a Class 1 spread of flames and also the (limited) amount of heat released from the surface of a product.
When the Euroclass classification system was introduced, many countries including the UK had a period where both the existing national standards (BS) were referred to alongside the mandatory harmonised European classification (EN). In UK building regulations (intended to be a transition period), both systems were used alongside each other and is still the case day. The issue caused is that Class 0 simply does not indicate or reflect the same performance as the Euroclass system does.
Class 0 is often compared to Euroclass B, because both are mentioned in existing regulations, but Class 0 is not comparable to a Euroclass system Class B.
The 2 classification systems differ in that the national Class 0 measures the spread of flame and the amount of heat release from only the surface of a product, whereas the Euroclass classification, EN13501-1, asseses the following: spread of flame, ignitability of sample, the amount of heat, smoke & toxic gaess release and whether the product melts, drips or chars. This is more important, the Euroclass system focuses on the combustibility of materials, not only the spread of flames. It is possible that a material classified as Euroclass B may also be classified as a Class 0 product however it can not be assumed the other way around. It is also worth noting that paints are available rated to class 0, this does however enhance the rating of the product underneath.
Choosing a Class 0 rated product is often prompted by the misunderstanding of the Euroclass B rating and indeed the comparisons often drawn between the 2 classification systems. In some cases a product rated to Class 0 may not even achieve a Euroclass B and could be of a less rating such as Class D or E which can lead to combustible products being specified. If you are unsure of the rating that should be specified for the cladding on a low-rise or high-rise building, it is best to avoid risks by simply choosing a product rated to Euroclass A2 (limited-combustible) or A1 (non-combustible).
Designing out risk will enssure the building will comply to current and future building regulations.
So what is the difference between A1 and A2?
Class A1 – Products are described as having no contribution to fire at any stage. BS EN 13501 sets several thresholds for combustion performance when tested to both EN ISO 1716 and EN ISO 1182. One of these thresholds is a maximum heat of combustion of 2MJ/kg. Typical products meeting this classification include most inorganic materials such as stone.
Class A2 – Products are described as having no significant contribution to fire at any stage. BS EN 13501 sets several thresholds for combustion when tested to EN ISO 1182, or both EN ISO 1716 and EN 13823. One of these thresholds is a maximum heat of combustion of 3MJ/kg. A typical product meeting this classification is plasterboard.
For comparison, Wood has a typical value of 15 MJ/Kg.
Class A2 products also are shown as having an ‘s’ and a ‘d’ after the rating (i.e A2-s1, d0) which refers to the smoke and burning droplets given off by the product. The ‘s’ stands for smoke emitted during testing and is measured in s1- s3 with s1 being the best performance. The ‘d’ stands for droplets and particles given off during testing and is measures in d0 – d2 with d0 being the best performance. Class A1 products are not rated for smoke or burning droplets and particles given off during the test.
For more information on these products and to learn more about the route to compliance, or to book a CPD, please call us now.