Specifier guide, Fire
Class B fire rating for flooring: Bfl-s1 and EN 13501-1 explained
When a floor finish has to satisfy the fire strategy, a protected escape route, a hospital corridor, a hotel circulation space, the figure that matters is its reaction-to-fire classification to BS EN 13501-1. Here is what Class B (Bfl-s1) means, where it is asked for, and how to specify it without getting caught out.
How floor fire ratings work: EN 13501-1
Floor coverings are classified for their reaction to fire under BS EN 13501-1, using a radiant-panel test (BS EN ISO 9239-1) that measures the critical heat flux at which flame spread stops, together with a small-flame ignition test (BS EN ISO 11925-2). The result is a class carrying the subscript “fl”, for flooring: A1fl and A2fl (effectively non-combustible), then Bfl, Cfl, Dfl, Efl and Ffl in declining order of performance. A separate smoke classification, s1 or s2, records how little smoke the product gives off, with s1 the lowest.
So what is Bfl-s1?
Bfl-s1 is a floor covering that makes a very limited contribution to fire, one step below the non-combustible A-classes, combined with the lowest smoke emission, s1. For combustible materials such as wood and cork that is a demanding bar: most untreated timber floors sit at Cfl-s1 or Dfl, so reaching Bfl-s1 generally means an engineered build-up or an additional fire treatment rather than the raw material alone.
Where Class B is required
National building regulations set minimum floor classifications by building type, height and location. In England, Approved Document B calls up reaction-to-fire classes for the linings and, in defined circumstances, the floors of circulation spaces and protected escape routes, and the more critical the escape route, or the taller and higher-risk the building, the higher the class specified. The practical point for the specifier is simple: the fire strategy or the regulations will state the minimum class for each area, and your task is to match the floor’s certified classification to it, for the exact build-up that will actually be installed. Hotel and restaurant circulation is where this comes up most often, see our hospitality flooring guide.
Always quote the full classification, including the smoke suffix, Bfl-s1, not just “Class B”. In an escape route, smoke is as dangerous as flame, which is precisely why escape-route specifications pair the fire class with s1.
Which of our floors can meet Class B
Reaction-to-fire class is product- and build-up-specific, so we issue the EN 13501-1 classification report for the exact product on request. As a starting point:
| Range | Reaction to fire | Notes |
|---|---|---|
| Winderen engineered oak | Cfl-s1 standard; Bfl-s1 available | Bfl-s1 achieved through an additional factory treatment, specify at order. |
| Vermont hybrid engineered wood | Bfl-s1 | Confirm the full classification, including smoke class, on the EN 13501-1 report. |
| Classic Cork | Bfl-s1 | Applies to the Classic Cork range; other cork styles differ, confirm per product. |
| Organic resilient | Cfl | Confirm the full classification, including smoke class, on the EN 13501-1 report. |
| Endgrain solid blocks | Classification report on request | Confirm the certified class for the specified build-up. |
Specifying it correctly
Three rules keep a fire specification clean. First, quote the whole classification, smoke suffix included. Second, remember the class belongs to the tested system, not just the wear surface, substrate, adhesive and underlay can all affect the result, so cite the class for the actual installed build-up. Third, obtain and keep the classification report itself rather than a marketing line, filed with the O&M and fire-strategy documents. Our NBS-format specification clauses and product TDS package exactly the data an architect needs to close this out.
Fire rating FAQ
What does Class B (Bfl-s1) mean for flooring?
Under BS EN 13501-1, Bfl-s1 is a floor covering that makes only a very limited contribution to fire, one step below the non-combustible A-classes, combined with s1, the lowest smoke emission. It is the class most commercial and specifier-grade hard flooring is expected to meet.
Where do UK Building Regulations require a Class B floor?
Approved Document B sets minimum reaction-to-fire classes by building type, height and location. Protected escape routes and higher-risk buildings are the usual triggers for Bfl-s1 rather than the lower Cfl-s1. Confirm the requirement for your project against its fire strategy.
Which of your floors meet Class B as standard?
Vermont hybrid engineered oak and Classic Cork are both Bfl-s1 as standard. Winderen engineered oak is Cfl-s1 (Class C) as standard and can be supplied to Bfl-s1 on request through an additional factory treatment.
Is Bfl-s1 the same as Class B?
Class B is the reaction-to-fire class; Bfl-s1 is the full classification for a floor covering, the fl denotes flooring and s1 the smoke sub-class. Always specify the full code, Bfl-s1, not just Class B, so there is no ambiguity on smoke.
Can you provide the EN 13501-1 classification report?
Yes. The classification report for the specified build-up is available on request and ships with your samples. Request samples and fire data via our contact page.