A2 to B1: Know the difference and specify with confidence

The type of ventilated cladding that’s so popular in modern construction can really improve thermal insulation properties, as well as enhancing the overall appearance of buildings. However, specifying the exact requirements of external cladding for your structures can be difficult if you don’t appreciate different standards and testing regimes. Our expert advisers can offer you any support you may need, so don’t hesitate to give us a call if you are having problems making the best decision on regulatory and aesthetic needs for your building.

First off, it’s important for you to note that new UK fire regulations came into place in December 2018, and are noted as Amendments to the Building Regulations 2010. A vast proportion of the new regulations relate to performance classes, and relevant British or European standards. You can access details on the entire document on the government’s website. We’re focusing on some of these changes in this guide, as these are relevant to our cladding and insulation products. And, also taking a look at what constitutes combustible and non-combustible material.

Our experts here at alsecco are constantly fielding client queries about fire classifications and the suitability of our cladding systems for different structures. This has been even more apparent since the awful Grenfell tragedy, so we’ve put this brief guide together to help you understand the differences between A-1, A-2, and B-1 when you’re specifying and how these fit in with UK Building Regs and BS8414 requirements.

So, what about A-1, A-2 and B-1? Where do they come in?

Basically, A-1, A-2, and B-1 classifications relate to European fire test standards which are tested under the Single Flame Ignitability Test EN ISO 11925-2, and the Single Burning Item Test EN 13823. The resulting values from all relevant testing provide EW1 material classifications ranging from B to F for performances.

A1 classes are a result of the Non-Combustibility Tests BS EN ISO 1182 and Heat of Combustion BS EN ISO 1716, while A2 classifications must meet all requirements of these two tests plus all the values noted in BS EN 13823.

All the above may seem a little complex, however, it’s important to note that these European classifications also form part of much of our British Standards testing regime. Therefore, products rated A-1 or A-2 (Non-Combustible) under European standards will also have been achieved positive results at BS EN ISO 1182 and BS EN ISO 1716, as well as approval under BS476 (part 4 or part 11) and BS8414 (accredited to BR135 or LPS levels).

What is the BS8414 test for?

The Fire Performance of External Cladding Systems is tested under BS8414, with non-load bearing external cladding falling under Part 2 of the test regime. If you’re interested in watching a video of the BS8414 being carried out, check out the Institute of Civil Engineers website.

Combustibility: What are non-combustible and combustible materials?

Stone wool or mineral wool is a fibre product which may also contain a small amount of resin binders. It is classed as either A-1 or A-2 throughout England, Wales and Northern Ireland, and A-1 in Scotland It can be supplied in slab or lamella form and is also used to form fire breaks.

The stringent testing carried out on A-1 and A-2 products work to compare the ignitability, heat release, flame spread, smoke production and the material’s likelihood of producing flaming droplets or particles. This testing is a standard throughout the EU, however, it is not currently compulsory in the UK.

All products achieving the A-1 classification are said to be non-combustible under UK regulations.

EPS or expanded polystyrene is a combustible material often used in systems, which is supplied with a flame retardant additive to enhance fire performance. Systems containing this product tend to have a B or C fire rating.

Systems including phenolic tend to be rated at B or C too and are recognised as having a low flame spread.

PUR (polyurethane) and PIR (polyisocyanurate) are both combustible in their physical forms but have good insulation properties and have been recognised as providing reduced combustibility in cladding products. A typical PIR system has a rating of B or C.

What do the new fire regulations actually mean to you?

To put it simply, the 2019 fire requirements have now banned the use of combustible materials in external cladding that is to be used for high rise residential structures. This detail is noted in Section I of the amendments to the Building Regs noted above. From January 2019 any new structure that has one or more storeys at 18-metres above ground level and also features residential dwellings must feature A-1 or A-2 standard cladding. Student halls of residence, care homes, apartment buildings, hospitals and private schools are included in the term “residential structure”. And, any cladding, balconies, solar panels or devices fixed to the exterior of these buildings are also included in this amendment.

Where existing buildings taller than 18-metres in height are being refurbished or converted to residential use, any materials which don’t comply with A-1 or A-2 requirements will need to be removed and replaced.

As can be seen from the above, the amendments to the Building Regulations are likely to make a vast difference if you’re designing a totally new structure above 18-metres in height that will feature residential accommodation. It’s also important for you to check out thoroughly all the materials utilised on the exterior of any refurb building at this height. The Grenfell tragedy had a deep impact on the psyche of UK consumers, particularly people living in high rise blocks. Repercussions are still apparent within our industry, in public authorities and government circles and in the wider population.

If you need any more help or advice regarding European testing at A-1, A-2 or B1 or want to discuss the full range of tests conducted on our alsecco cladding and insulation products, don’t hesitate to get in touch.

fire, fire safety


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