Post-Grenfell fire safety legislation reshaped how the industry approaches building materials, and while much of the focus fell on external walls, the tighter culture around evidence and accountability now extends to interior wall finishes too. Building control teams look at interior cladding with far greater scrutiny. The testing standards behind those finishes are still widely misunderstood, and the rules changed again in 2025. Here is what specifiers need to check before they sign anything off.
How Fire Classification Changed in 2025
Until recently, two classification systems ran side by side for interior wall cladding in England. The older British Standard, BS 476 Parts 6 and 7, measures fire propagation and the surface spread of flame, giving familiar ratings such as Class 1, which construction teams relied on for decades. Class 0 sits above this, but it’s worth noting it’s a building regulations classification rather than a single test result, awarded when a material achieves Class 1 under Part 7 and also meets strict fire propagation limits under Part 6
Then you have the European system, BS EN 13501-1, which classifies materials into Euroclasses from A1 and A2 (non-combustible and limited combustibility) down through B, C, D, E and F. It also adds extra ratings for smoke production, shown as s1, s2 or s3, and flaming droplets, shown as d0, d1 or d2. A Euroclass B-s1, d0 rating means the material contributes very little to a fire, releases minimal smoke and creates no flaming droplets.
The important change is that this is no longer a live choice between two systems. On 2 March 2025, the BS 476 reaction-to-fire classifications were withdrawn from Approved Document B, leaving BS EN 13501-1 as the only accepted route for reaction to fire in England. Any product still relying solely on a Class 0 or Class 1 rating for new specification is now working from a withdrawn standard. References to BS 476 for fire resistance remain in place until September 2029.
Approved Document B of the Building Regulations outlines where you must use these specific ratings. A common mistake is treating an old Class 0 rating as if it maps neatly onto a Euroclass score. The two rely on different test methods, so a Class 0 product won’t automatically achieve a high Euroclass result, and for new work it now needs an EN 13501-1 classification regardless.
How Internal Finishes Impact Commercial Project Approval
In sectors like healthcare, food production and education, interior walls must meet strict hygiene and fire safety rules at the same time. Specifiers can’t lean on cleanability instead of checking the exact reaction-to-fire classification. Good suppliers make this easy by publishing their test data. For instance, teams sourcing PVC hygienic wall panels from Simply Cladding can access published fire test data to verify compliance before installation, which is the level of documentation any specifier should expect as standard.
This data matters because different areas within a hospital or school require different levels of protection. Corridors and escape routes demand the highest safety standards to protect occupants during an evacuation. Choosing the wrong panel because of a misunderstanding about compliance can lead to building control rejecting the entire fit-out.
A panel that works well in a low-risk office might fail to meet the standards required for a commercial kitchen or a hospital operating theatre.
The Difference Between Reaction and Resistance
Confusing reaction-to-fire testing with fire resistance testing is one of the most common specification errors on modern fit-out projects. They measure entirely different behaviours. Reaction tests show how an individual material behaves when it’s exposed to an open flame, such as how fast it burns or how much smoke it creates.
Fire resistance tests measure how long a complete construction element, like a full wall assembly, can hold back fire and heat. This is expressed in minutes, such as a 30-minute or 60-minute fire wall. A panel with an excellent reaction-to-fire rating won’t give a wall structural fire resistance on its own.
Specifiers must evaluate the entire wall build-up, looking at the insulation, the framing and the fixings alongside the outer panel. Install a fire-rated panel onto a flammable timber frame without the right design, and the wall won’t perform as expected.
What to Request From Panel Manufacturers
You can’t rely on generic fire rating claims on a website or brochure. Under the Building Safety Act 2022, building control scrutiny is tighter than ever. It’s worth knowing where this bites hardest. The formal ‘golden thread’ duty under the Act applies to higher-risk buildings, broadly those at least 18 metres tall or seven storeys with two or more residential units. Hospitals and care homes fall within the regime during design and construction but are excluded from the in-occupation duties, while schools sit outside the definition entirely. Even so, keeping a clean documentation trail is now expected practice on any commercial fit-out.
Request the following before you approve a product:
- Official third-party test certificates from an independent body.
- Declarations of performance that detail the exact fire characteristics.
- Full laboratory reports from a UKAS-accredited testing facility.
When you review these reports, look closely at the exact product configuration the lab tested. A panel that passes at 2.5mm doesn’t automatically carry the same rating at 3mm. Changes in thickness, backing materials or adhesives can completely alter how a material behaves in a real fire.
It’s also vital to check the testing is current. Standards change, and since March 2025 any reaction-to-fire evidence resting on the withdrawn BS 476 classifications will no longer satisfy a building inspector, however recent the certificate looks.
Get the Classification Right Before You Specify
Specifying interior finishes requires strict attention to the latest testing standards and building regulations. Relying on outdated terms or unverified supplier claims puts your entire project at risk. Check every certificate against the specific set-up you plan to install on-site, and keep a complete paper trail to satisfy building control and protect long-term occupant safety.
