What is BS 6229:2025 - Flat roofs with flexible waterproof coverings about?
BS 6229:2025 is a national code of practice for the design, construction, care, and maintenance of flat roofs (or curved roofs with a pitch not greater than 10 degrees) that use continuously supported flexible waterproof coverings.
It covers roofs supported by either heavy structures (like concrete slabs) or lightweight decks (metal or timber-based).
The standard describes good current practice and aims to address gaps that have led to defective roofing solutions, especially where designers were unaware of building physics issues such as vapour resistivity differences between vapour control layers and roofing membranes.
Who is BS 6229:2025 - Flat roofs with flexible waterproof coverings for?
This standard is intended for all parties involved in the design, specification, installation and maintenance of flat roofing. This includes:
- Architects
- Manufacturers
- Main and specialist contractors
- Building maintenance service providers
- Construction product suppliers
- Roofing companies
- Structural/civil engineering service providers
- Waterproofing & insulation providers
- General building contractors
It is also relevant to trade associations, industry bodies, professional institutions and consumer/public interest organizations in the construction sector.
What does BS 6229:2025 - Flat roofs with flexible waterproof coverings cover?
BS 6229:2025 covers:
- Good practice for the design, construction, care, and maintenance of flat and curved roofs with flexible waterproof coverings.
- Recommendations for roofs at pitches greater than 10 degrees and those with multi-functional finishes, provided design conditions are similar.
- It does not apply to certain types of cold stores and high-temperature enclosures.
- The standard applies to the full life-cycle of flat roofs, from design through to maintenance, aiming to prevent defective installations.
Why should you use BS 6229:2025 - Flat roofs with flexible waterproof coverings?
Using BS 6229:2025 ensures your roofing projects are designed, constructed, and maintained to the highest industry benchmarks, helping you avoid costly mistakes and future defects. It fills a critical gap in guidance, offering up-to-date best practice where no equivalent European or industry standard exists.
This standard:
- Provides comprehensive guidance for the full life-cycle of flat roofs, from design through to maintenance.
- Addresses gaps that have led to defective roofing installations, especially around building physics and vapour control.
- Helps prevent recurring issues by setting out good current practice.
- Supports entry into new markets and accelerates innovation in roofing solutions.
- Enables you to develop expertise and facilitate trade within the construction sector.
- Promotes sustainable growth and improves operational efficiency.
- Increases trust in your work and helps you manage risk effectively.
- Applies to a wide range of professionals: architects, contractors, manufacturers, maintenance providers and more.
- Reflects the latest updates in design (especially drainage), materials, care, and maintenance.
- Aligns with sector strategies for building safety, quality and climate action.
What's changed?
BS 6229:2025 supersedes BS 6229:2018. The revision was prompted by a 5-year review of identifying content that required updating.
The changes introduced in BS 6229:2025 include:
- Major updates to Clause 4 (Design), especially the sub-clause on “Roof falls to achieve drainage”.
- Updates to Clause 5 (Materials), Clause 7 (Care and maintenance) and the terms and definitions.
