What does the withdrawal of the BS 476 series from Approved Document B really mean for the industry?

Since the government confirmed that the fire testing standards used for National Classifications will be withdrawn from ‘Approved Document B’ in favour of the EN 13501 series of European classification standards, there has been confusion about the differences between the two systems. Most worryingly however is the misunderstanding that the transition is required because the British Standards are not robust enough – this is incorrect and causing unnecessary concerns regarding fire safety in the construction industry.

Unpacking the changes

Many of the changes we’re seeing in fire safety regulation are the result of the Grenfell Tower tragedy and the recent Inquiry putting a much-needed spotlight on fire safety in buildings.

However, the withdrawal of the BS 476 series from Approved Document B is a recognition of an ambition by the UK Government to have a single classification system supporting the fire performance of construction products. More recently the government has also stated that the withdrawal of BS 476 implements the recommendation made in the Hackitt Report, for a clearer, transparent and effective safety regime, while the existence of two testing and classification systems was also raised as a concern in the Independent Review of the Products Testing Regime.

A major concern highlighted as part of the Grenfell Tower Inquiry focused on the testing and classification system for reaction to fire because of the way the insulation and rain screen cladding on the outside of the tower were assessed. However, no similar concerns were raised regarding the fire resistance testing and classification of the flat entrance doors, as the existing national classification system for fire resistance does not show similar weaknesses.

The key findings of the Grenfell Tower Fire Inquiry, relating to the flat entrance doors, as stated in the Phase II report were:

• The Tenant Management Organisation (TMO) had not specified the flat entrance doors correctly. They had called for FD30 doorsets not FD30S.
• The fire doors had only been tested for fire resistance and insulation but not smoke control.
• The fire doorsets had only been tested in one direction.
• There were issues relating to the automatic closers that had not been installed correctly and were not repaired.
• The operation of the automatic closers was not sufficiently covered in the fire safety risk assessment.

There were no concerns relating to the fire resistance of the fire doors claiming a national classification FD30 based on testing in according with BS 476-22.

The British Woodworking Federation and BWF Fire Door Alliance believes these issues have been mistakenly conflated with broader fire resistance concerns, leading to unwarranted doubts about the reliability and performance of timber fire doors tested under BS 476-22.

The reliability of timber fire doors was in fact proven by an MHCLG investigation following the Grenfell Tower fire. All of the timber fire doors tested passed the 30-minute standard in both directions, and the investigation concluded that timber fire doors perform consistently when tested for fire resistance and pass the 30-minute required standard when manufactured to specification. MHCLG stated their investigation found “no issues with the consistency of fire resistance performance of the doors tested”. Many BWF members who  had their fire doors put through the government commissioned fire-resistant tests, reported exceptional protection and exceeded the 30-minute performance by a significant margin. On average, across the data submitted, fire-resisting time was at 46 minutes, surpassing the 30-minute requirement on average by 16 minutes.

The performance of fire doors tested to the British Standard has been proven as robust and reliable, further demonstrating that the transition to the European standard is part of the Government’s aim to unify the UK’s testing systems and remove concerns about having two systems for determining the performance of a fire door.

The European testing classification is the most recent standard and is also currently being reviewed to further improve its effectiveness and reduce risks in the process – which will help future proof the testing process.

Dispelling myths between the classifications

When directly comparing the classifications, the differences between BS 476-22 and BS EN 1634-1 are nuanced and it’s important to fully understand the three key factors surrounding fire resistance:

1. Both BS 476-22 and BS EN 1634-1 use the same time temperature curve from ISO 834-1 to control the temperature within the furnace.
2. BS 476-22 uses unshielded thermocouples to monitor the furnace temperature while EN 1634-1 uses shielded thermocouples that are less responsive to the changes in temperature resulting in increased heating energy in the early stages of the test.
3. The neutral pressure plane is positioned lower relative to the notional furnace floor level in a BS EN 1634-1 test (500mm compared to 1000mm) resulting in greater relative positive pressure conditions at the top of the door which potentially increases hot gases and flaming on the unexposed side.

Potential timeline challenges

While the transition deadline has been set for 2029, conformity marking may impact the timeline. The technical committee responsible for drafting the product standards for fire doors is expecting to receive instruction from the European Commission following the processes established under the new EU Construction Product Regulation (CPR).

This means that it is possible for new European Product Standards, replacing EN 14351-1, EN 14351-2, EN 13241 and EN 16034 to be available before the Government’s target date.

The upcoming UK Construction Products Regulations will also shed more light on things like “safety critical products” and whether the UK Government will assimilate the new EU CPR. These and other changes in National or European Regulations may force changes within the Building Regulations within the next five years that cannot be foreseen at this time, therefore we advise the industry to be aware of this.

What steps to take now

As the standard change comes into effect in 2029, specifiers and facilities managers can remain confident in the fire doors in the buildings for which they are responsible that have been rigorously tested to the BS 476-22 standard.

To be certain of a fire door’s performance, it’s important to use a third-party certified fire door, such as those manufactured by members of the BWF Fire Door Alliance. Third-party certification provides crucial independent evidence that a fire door, when correctly installed and maintained, is fit for purpose and complies with fire door regulations.

The BWF will continue to work with the National Standards Body BSI and the European Standards Body CEN to ensure that the European standards deliver robust results. We will also be working closely with our manufacturing members to transition to the new system ready for the 2029 deadline.

In the meantime, for those responsible for fire doors within buildings, there’s no need to replace fire doors that meet the British Standard which are correctly installed and maintained by a competent person, and remain fit for purpose.

Now is the time for those responsible for fire doors to gain a full understanding of the testing systems and the upcoming changes to ensure they are prepared when the transition takes place in 2029.