EDUCATING BUILDING OWNERS ON THE MISCONCEPTIONS OF FIRE SAFETY IN RISER SHAFTS NEEDS TO HAPPEN NOW By Alex Bardett, Managing Director at Ambar Kelly

February 01 2025

Fire safety has increasingly come into focus in recent months, following the Grenfell Tower inquiry. This has increased the importance of riser shafts and the significant roles they play in improving safety and reducing the spread of fires in higher risk buildings (HRB). Despite this, there are a number of misconceptions relating to riser shafts that need to be debunked. Alex Bardett, Managing Director of Ambar Kelly, challenges these misconceptions and reveals the importance of implementing non-combustible modular riser flooring to improve HRB fire safety.

While building regulations relating to fire safety have seen significant changes in recent times, the construction industry still faces many fire safety challenges, particularly when it comes to the perils of installing combustible materials and perceiving non-combustible alternatives to be more expensive.

According to the Home Office’s online Incident Recording System (IRS), there were 707 fires in high-rise buildings in England in the year ending September 2023, a 17% decrease compared to 10 years ago. While this is a pleasing drop, the data highlights the risk that fires still present, especially in HRBs, and why better understanding and stricter regulation is vital.

The recent Grenfell Tower inquiry recently illustrated how chosen materials can have a significant impact on the spread of smoke and fire throughout HRBs. Indeed, the 2017 tragedy involved a combustible material being lit and then, amongst other things, a fire rising in a void and forming a vertical shaft due to the lack of a horizontal fire break.

Furthermore, the King’s Cross station fire of 1987 involved a shaft ‘trench effect’, when a discarded match lit a combustible material and then developed into a ‘flash over’ due to the fire rising in the ‘trench’ of the wooden escalators.

While the upcoming Building Regulation changes shedding more light on fire testing and certification is a positive step forward, more information and education on the vital role non-combustible products play in improving HRB safety is essential.

How will upcoming changes to building regulations and fire safety impact the industry?

Significant changes to fire safety and evacuation provisions, including Approved Document B, are coming, thanks to a new parliamentary statement issued by the Ministry of Housing, Communities, and Local Government (MHCLG). Consequently, fire safety must be given to the relevant duty holder when the project is complete or when the building is first occupied.

Being introduced on 2^nd March 2025, the new updates will remove references to the national classification system for fire resistance, known as BS476. Parts 6 and 7 will require construction projects to be classified in accordance with EN13501-1, with performance classes A1 and A2 for non-combustible products and B, C, D, and E for combustible products.

Having a fire rating does not mean non-combustibility

Products will often be promoted by suppliers as having a BS476 Part 6 & 7 fire rating. This is actually a measure of the spread of flame and is common for GRP grating used as a riser flooring solution.

However, all GRP grating is combustible and will add fuel to any fire that occurs in a riser shaft. Indeed, the Grenfell Tower inquiry found this surface spread of flame test (BS476 Part 6 & 7) does not measure combustibility, hence why it is being withdrawn in March 2025.

If the designed riser flooring is specified as non-combustible at Gateway 2, contractors may believe the GRP grating has the required ‘fire rating’ and attempt to hand the project over to Gateway 3. However, it is likely to be rejected as, despite having a BS476 Part 6 or 7 declaration, it is combustible. Which leads us to…

Misconceptions over responsibility

Believing the product’s supposed fire rating is correct, most contractors will often hand over the project to the next person in the chain. In fact, there are often occasions when a main contractor will claim the sub-contractor has bought it and said it is fire rated, so it isn’t their problem. However, it isn’t always that straightforward.

The main contractor will often hold all the risk without realising they are in this position. Additionally, if a non-combustible class A1 steel riser flooring product is specified in Gateway 2 and replaced by a combustible Class C GRP product, this needs to be recorded in the change control plan so the impact of the combustibility changes can be considered.

It's important to note any changes must also be documented before the Building Safety Regulator (BSR) signs off the building for handover at Gateway 3.

Non-combustible products are perceived to be more expensive

There is a perception among many in the construction industry that non-combustible steel plate materials, featuring pre-cut holes for M&E services that are covered by a lid, are too expensive. While initial costs may be more, these costs won’t increase as the project progresses.

Conversely, any outlay for combustible riser flooring options will typically increase over time, due to necessary post-installation works. For example, GRP grating has to have holes cut into it to account for any services being fed through. Temporary fire doors will also need to be fitted on every floor to meet codes of practice and prevent the spread of fire during construction, as by its very nature, grating allows smoke and flames to pass through. This increases the overall project cost.

The importance of education and increasing awareness

Fire safety in any building is vital, especially HRBs. It is therefore absolutely imperative that main contractors and suppliers are educated on the benefits of non-combustible materials.

The Golden Thread, introduced in recent years, is playing a vital role in this regard, giving anyone involved in a project immediate access to up-to-date information to help them gain a better understanding of the fire risks of using certain materials and the importance of spotting issues early.

Furthermore, it’s also vital the government works together with industry leaders to ensure regulations are being complied with and quality standards are being adhered to. Benefitting the end user and the contractor, this will improve the quality of materials being used in construction.

While it is essential that contractors are more aware of their responsibilities if they change a specified non-combustible product for a cheaper combustible alternative, suppliers must also do more. For instance, any products must be tested and certified to EN13501-1 to enable design teams and contractors to make an informed comparison between products.

With the tragic events at Grenfell Tower highlighting the importance of fire safety, the need for contractors to be aware of the benefits and opportunities of utilising non-combustible materials in the construction of any building, but especially HRBs, has never been more intense. Similarly, it’s also imperative that all involved in the construction industry are aware of the risks that come with using combustible materials.

Increasing awareness on the common misconceptions surrounding fire safety in riser shafts and helping to educate those inside and outside the built environment on the benefits of non-combustible materials will go a long way towards ensuring better built and safer buildings across the UK.