Fire safety has never been more central to construction design and compliance. With increasing regulatory focus across the United Kingdom, specifiers and project managers are now required to ensure that every building material used, from cladding to roof coverings, meets strict non-combustibility standards.
Among the many roofing materials available, natural slate remains one of the safest, most reliable, and most thoroughly documented options. But what does that mean in terms of fire testing? Does natural slate achieve an A1 classification?
The short answer is yes, natural slate is classified as A1 non-combustible under the Euroclass system, confirming that it will not ignite or contribute to the spread of fire. In this article, we’ll explore what that means in practice, when and where this classification applies, and what documentation specifiers should expect from their supplier. We’ll also explain how SSQ’s Del Carmen and Riverstone ranges provide complete confidence for high-value projects requiring verified fire performance.
Understanding the Euroclass system
Across Europe, the Euroclass system (BS EN 13501-1) provides a standard for assessing the reaction-to-fire performance of construction products. It is recognised throughout the UK under Approved Document B of the Building Regulations.
The system categorises materials from A1 (non-combustible) to F (highly combustible), and the classification considers factors such as ignitability, heat release, flame spread, smoke production, flaming droplets.
An A1 rating represents the highest possible level of fire resistance. It means that the material does not ignite, produce smoke, or emit flaming droplets, even when directly exposed to fire. Products achieving A1 status require no additional testing for smoke or droplets, their performance is already proven to be inherently non-combustible.
Why is natural slate classed as A1?
Natural slate, a metamorphic rock formed over millions of years, is composed primarily of quartz, mica, and chlorite, minerals with exceptionally high melting points. These characteristics mean it will not burn, melt, or emit smoke when exposed to fire.
Because of these intrinsic properties, natural slate is listed in Commission Decision 2000/553/EC as a material that is deemed to meet all fire performance requirements without the need for laboratory testing. This exemption is written directly into both EU and UK legislation. Despite the UK’s departure from the European Union, this directive remains in force and continues to be recognised in Approved Document B, which explicitly names natural slate as a roofing material that fulfils all external fire performance requirements.
As natural slate is A1 non-combustible it can be used anywhere that a non-combustible roof covering is required.
Where and when does the Euroclass system apply?
The Euroclass system applies to all construction products placed on the market within the UK and Europe, but its use is particularly critical in buildings where fire safety is paramount. Typical applications include:
- High-rise buildings (generally over 18 metres)
- Hospitals and healthcare environments
- Student accommodation and residential blocks
- Public buildings and transport hubs
For these projects, designers must specify A1 or A2-s1,d0 rated materials to reduce the risk of fire spread through the external envelope.
Even for lower-rise or domestic projects, compliance teams increasingly favour A1-rated roofing materials like natural slate to demonstrate best practice and long-term risk management. It ensures that the roof, which is one of the most exposed parts of any building, does not contribute to the spread of fire, regardless of the surrounding materials or external weather conditions.
What documentation should specifiers expect?
When specifying roofing slates, compliance depends on accurate, traceable documentation. Reputable suppliers like SSQ provide all the evidence required to confirm the natural slate A1 fire classification under BS EN 13501-1.
You should expect to receive:
- Declaration of Performance (DoP) – this legally required document states the product’s characteristics, including its fire classification (A1). For natural slate, the DoP may reference the exemption under Commission Decision 2000/553/EC.
- Manufacturer’s technical data sheet or certificate – this confirms that the slate roofing material is A1-rated and compliant with all relevant European and British standards.
- Building regulations compliance statement – suppliers like SSQ can provide written confirmation their natural slates meet the requirements of Approved Document B and can be used wherever non-combustible roofing products are specified.
These documents together provide complete assurance that the product is fit for purpose, fully tested (or exempted), and in accordance with national regulations across England, Scotland, and the wider UK.
Why is the natural slate A1 fire classification so important?
The risk of fire in modern construction is a major concern for both compliance and reputation. Selecting a roofing material with verified non-combustibility eliminates uncertainty and demonstrates full due diligence. An A1 classification gives peace of mind in several key areas:
- Safety – Natural slate will not ignite or add fuel to a fire.
- Compliance – Meets or exceeds the most stringent building standards.
- Insurance and liability – Reduces exposure for contractors and developers.
- Longevity – Fire performance remains stable throughout the material’s long service life.
For specifiers and contractors in the United Kingdom, this level of assurance is invaluable, particularly on complex, high-profile developments where scrutiny of every building material is now standard practice.
How does natural slate compare with other roofing materials?
Not all roofing materials offer the same level of protection.
Clay and concrete tiles are typically classified A1 or A2, though consistency depends on the exact formulation, while metal roofing can deform under heat and may require additional insulation to meet fire resistance criteria. Synthetic slates and composite roof tiles often contain polymers or bitumen, making them combustible and unsuitable for buildings requiring non-combustible materials.
Natural slate, by contrast, is entirely inorganic. It is a natural stone, unaffected by temperature, resistant to weather conditions, and non-combustible. It not only satisfies fire performance requirements but also provides unmatched durability, aesthetic value, and a service life exceeding a century when installed correctly.
From traditional heritage restorations to contemporary architectural designs, A1-rated natural slate roofing tiles provide a resilient, attractive, and fully compliant solution for today’s stringent building environments.
SSQ Del Carmen: World-class Spanish slate with A1 assurance
Del Carmen is one of SSQ’s most trusted and widely specified roofing slates. Quarried from a single, consistent vein in northern Spain, Del Carmen is renowned for its deep blue-black colour, fine grain, and exceptional uniformity.
Every Del Carmen slate is A1 classified, W1-T1-S1 rated, and certified to BS EN 12326, the European standard for natural roofing slates. It also meets NF 228, the toughest French quality standard, and is officially accepted by English Heritage and Heritage Scotland as a suitable alternative to indigenous Welsh slate.
Its key benefits include:
- Proven A1 non-combustible classification
- Low water absorption for superior freeze-thaw resistance
- Durability and stability across extreme weather conditions
- Up to 100 years of service life, depending on grade
- Certified for use on heritage, restoration, and premium new-build projects
Del Carmen’s consistent quality makes it a favourite among architects seeking authenticity, safety, and longevity in roofing slates from Spain.
Riverstone phyllite: The ultimate non-combustible roofing material
Even tougher than slate, Riverstone phyllite represents the pinnacle of natural roofing performance. Quarried exclusively by SSQ in La Repressa, Argentina, Riverstone is a metamorphic stone over 560 million years old, formed under immense geological pressure.
This process produces a material that is denser, harder, and stronger than conventional slate, with a distinctive grey sheen created by tiny mica crystals. Like all natural stone of its kind, Riverstone is completely non-combustible and therefore qualifies as A1 under the Euroclass fire classification system.
Its certifications include:
- BS EN 12326 – W1-T1-S1
- ASTM C406
- Backed by a 100-year weathertightness guarantee
Riverstone’s exceptional density means it performs superbly under all weather conditions, from the cold, wet climates of the UK to the heat and UV exposure of southern Europe. For architects and specifiers requiring both visual refinement and guaranteed compliance, Riverstone is the ideal roofing material for premium developments worldwide.
What makes SSQ a trusted partner for compliant roofing slate?
With more than 40 years in the slate industry, SSQ has built its reputation on sourcing and supplying only high quality natural roofing slates from the world’s most reputable quarries. Every batch is tested, traceable, and certified in accordance with the latest European and British standards.
SSQ provides:
- Full Declaration of Performance documentation
- Long-term partnerships with elite Spanish quarries
- Exclusive ownership of the Riverstone quarry in Argentina
- Dedicated technical support for architects and specifiers across the UK
- Proven compliance with BS EN 12326, NF 228, and BS EN 13501-1
Key Takeaways
In an era where safety, compliance, and sustainability define success, natural slate remains one of the most dependable building materials available. Its A1 non-combustible rating, confirmed under the Euroclass system, provides guaranteed protection against the spread of fire, without the need for additional testing.
When sourced from trusted suppliers such as SSQ, with fully traceable documentation and certification, specifiers can confidently use natural slate for any project that requires verified non-combustibility.
Ready to specify A1-rated natural slate?
Whether your next slate roof project is in England, Scotland, or further afield, SSQ roofing slates deliver the assurance of true A1 non-combustibility, outstanding craftsmanship, and unmatched service life. For technical guidance, specification documents or project advice, contact SSQ’s specialist team today.
Frequently asked questions
What is the fire rating of natural slate?
Natural slate is classified as A1 under the Euroclass fire testing system (BS EN 13501-1). This means it is completely non-combustible and will not contribute to the development or spread of a fire.
Can A1-rated natural slate be used on all building types?
Yes. Because of its non-combustible A1 classification, natural slate can be safely specified for any building type; from domestic homes to high-rise residential, commercial, and heritage projects.
Is natural slate always the best choice for non-combustible roofing?
For projects that demand complete peace of mind, yes. Natural slate tiles combine fire resistance, durability, low maintenance, and timeless beauty in a way no synthetic alternative can match.
