What you need to know.
What has changed?
From January 1, 2025, the British Standards (BS) for floor detailing has been replaced by the more stringent European Norm (EN) standards – EN 14250. This shift will impact the availability and application of certain joist sizes:
195mm I-Beams (JJI-Joists) : These face restrictions due to updated performance standards for fire and sound.
202mm deep Posi-Joists : These are facing similar restrictions..
These changes are driven by evolving performance standards for both fire safety and sound insulation requirements. For instance, the NHBC’s 2024 Standards emphasize updated deflection limits and spacing requirements for timber I-Joists. Rather than enforcing a blanket ban on all 195mm JJI-Joists or 202mm Posi-Joists, the evolved standards may indirectly impact product selection based on performance.
Currently, 200mm deep floors require 100mm of mineral wool insulation to achieve the 40dB airborne sound resistance requirements set out in Building Regulations. However, there are no fire tests available for 200mm deep floors with this insulation included. This, combined with the NHBC and other regulatory bodies focusing more on integrating solutions that combine fire resistance with acoustic and structural performance, have led to a change in regulations.
Smaller joists that may not meet new standards for fire resistance and acoustic performance can still be used in roof structures under different regulatory guidance. This aligns with the trend toward using deeper joists (220mm or more) for better performance and space for services such as Mechanical Ventilation with Heat Recovery (MVHR).
In the UK, CE markings were due to be phased out by June 2025, however the UK Government announced an extension in September with no new definitive date.
IMPLICATIONs for your projects
Design and Material Selection
These regulatory changes necessitate adjustments in design and material selection:
Joist Depths: To comply with new standards, consider using joists with depths of 220mm or more.
Material Specifications: Ensure that materials meet the updated performance standards for fire safety and sound insulation.
Product Availability: Be aware that certain joist sizes may become less available or discontinued.
It’s crucial to stay informed and consult with suppliers and design teams to ensure compliance with the new regulations to ensure your project remains compliant and safe.
What does this mean for us
as part of your supply chain.
MiTek will continue to offer PS8 webs for posi rafters and attic designs, with fire-tested solutions starting at 147mm floor joists. While we design the floor joists, building designers remain responsible for ensuring fire and acoustic standards are met.
Moving forward, while we cannot supply 202mm Posi-Joists for flooring applications, they can still be supplied for roofing structures due to different regulations. If you would like to specify these in your roofing project, please speak with our design team who will be able to advise further.
In addition to these changes, the Building Safety Act (BSA) plays a significant role in reshaping the industry. The BSA holds developers and contractors accountable for historic construction issues and introduces a National Regulator for Construction Products. This act emphasises the importance of the “golden thread” – clear, consistent, and accessible documentation, which has a broad impact on all products, not just joists. The golden thread will enforce more stringent accountability and safety measures across the entire supply chain.
FINAL THOUGHTS.
Hampshire Engineered Timber Solutions (HETS)
The upcoming changes in flooring joist regulations represent a significant shift towards enhanced safety and performance standards in the construction industry. At HETS.UK we are proactively adjusting designs and materials to align with these new regulations, you can ensure compliance and contribute to the advancement of building safety.
We always continue to implement tight regulations around all products to guarantee each customer gets the best flooring solutions that comply with all regulations. We closely monitor the ever-changing construction industry to ensure all standards are up-to-date.
