The roofing industry has entered an exciting new chapter with the publication of BS 6229:2025, the updated code of practice for flat roofs with continuously supported flexible waterproof coverings. At Triflex, we welcome this revision. It reflects the evolving role of flat roofs in modern construction and urban design, and it provides much-needed clarity for specifiers, contractors and building owners.
Why this update matters
Flat roofs are no longer just functional barriers against the elements. Today, they serve as multi-functional spaces housing solar PV systems, plant equipment and even recreational areas such as terraces and podiums. BS 6229:2025 acknowledges this transformation by introducing clearer definitions and guidance for these diverse applications. The term “multi-functional finishes” now formally describes roof surfaces that deliver more than waterproofing, supporting sustainability, biodiversity, energy generation and climate resilience. They are also used to provide terraces and areas that can be used as direct access / leisure areas with multiple finishes.
This recognition aligns perfectly with Triflex’s philosophy: roofs should be designed for performance, longevity and adaptability.
Key changes: Falls and drainage
One of the most discussed updates is the adjustment to roof falls. The standard continues to recommend a minimum finished fall of 1:80, but it now acknowledges that tapered insulation schemes designed at 1:60, can result in a finished fall of 1:85, along the mitre, which is acceptable. This subtle change reflects practical realities on site while maintaining drainage performance.
Why is this important? Effective drainage prevents ponding, which can stress waterproofing, add unnecessary load and increase leak risk. However, Triflex waterproofing resins are hydrolysis-resistant, meaning they will not break down in water. This offers reassurance for refurbishment projects where correcting falls is challenging. While we always advocate for proper drainage to avoid ponding, clients can be confident that our systems maintain their integrity even in standing water, an important consideration for overlays on older structures.
The importance of surveys and bespoke project specifications
BS 6229:2025 places strong emphasis on condensation risk analysis, thermal performance and correct detailing, especially for refurbishment projects. This is where Triflex excels. Every overlay solution we support begins with a free, flat roof survey, assessing:
- Current condition and existing build-up
- Moisture presence with testing services
- Condensation risk analysis based on building humidity class
Warm roof upgrades, inverted systems and hybrid constructions all carry unique challenges. Our bespoke project specification proposals ensure compliance with BS 6229 while addressing project-specific needs. For example, when planning an overlay, we evaluate vapour control continuity, insulation performance and detailing at penetrations, critical factors for long-term success. In addition, condensation risk analysis and wind uplift calculations are provided.
Overlay solutions: our specialism
Overlaying existing waterproofing is often the most sustainable and cost-effective approach, avoiding unnecessary strip-outs and reducing waste. Triflex has been a specialist in overlay systems for decades, delivering solutions that extend roof life while meeting modern performance standards. BS 6229’s guidance on AVCL integrity, thermal bridging and interstitial condensation reinforces the importance of expertise in this area.
Supporting projects from consultation to delivery
The new standard stresses information exchange and project scheduling, ensuring all stakeholders have accurate data at the right time. At Triflex, we make this happen through our Project Support Services, which include:
- Waterproofing condition surveys
- Bespoke project specification proposal to the latest standards
- On-site technical support
- Quality assurance inspections and reporting where required
Our Technical Centre and field-based technical services team work hand-in-hand with specifiers and contractors, providing guidance from concept to completion. This collaborative approach reduces risk, improves efficiency and guarantees compliance.
Workmanship and training: A core principle
BS 6229 rightly highlights that the long-term performance of a flat roof depends on quality workmanship. Poor detailing at penetrations or outlets can lead to premature failure, regardless of design intent. Triflex addresses this through our network of trained and authorised contractors, who receive rigorous product and installation training. They are supported by our technical team on and off-site, delivering quality solutions we are proud to put our name to. This commitment to excellence is why Triflex systems consistently deliver durability and peace of mind.
Looking ahead
BS 6229:2025 is more than an update, it is a reflection of how flat roofs have evolved into critical, multifunctional assets in modern buildings. By providing clearer guidance on drainage, thermal performance, condensation control and information management, it sets a higher benchmark for design and installation. At Triflex, we are proud to align with these principles. Our expertise in overlay solutions, bespoke specifications and project support ensures that every roof we work on meets, and often exceeds, the expectations set out in the new standard.
If you are planning a refurbishment or new build, partner with Triflex for a solution that combines compliance, sustainability and long-term performance.
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