BS 6229:2018 – Keep up to Date with Changes in British Standards for Roofing
In November, 2018, one of the major British Standards for roofing, BS 6229:2018 Code of Practice for flat roofs with continuously supported flexible waterproof coverings, was published. The Standard contains an overall recommendation for the design, specification, installation and even the ongoing maintenance of a flat roof. This replaces the 2003 version and is quite a bit shorter, due to the fact that sections relating to metal roofs have been omitted and guidance for these has passed to the metal roofing industry and BS Committee B/542.
The new Standard acts as a readable, easy to understand and user-friendly reference resource with no non-essential details to confuse matters. It has been written to reflect how the flat roofing industry has evolved and changed over the years, partly as a result of the challenges resulting from Building Regulations and fire requirements, but also as a result of so much progress in new materials and systems.
BS 6229:2018 outlines best practice in the design, construction, care and maintenance of roofs with a flat or curved surface, with a pitch no greater than 10 degrees to the horizontal and with a continuously supported flexible waterproof cover material. The supporting structure for the waterproof covering can be dense or heavy, for example:
- Timber-based material mounted on framing members
- A lightweight metal deck
- A concrete slab
The new British Standard contains some new terminology that has come into use since the old 2003 version was written:
- Zero Fall Roof – this is specifically defined as a “roof with a fall between flat and 1:80”.
- Blue Roof – designed to reduce the rate at which rainwater drains from the roof and into the drainage system, this is used in Sustainable Drainage Systems (SUDs) and helps the building to comply with BREEAM and Building Regulations. This also helps to prevent damage to soakaways – we published a comprehensive description of blue roofs last year.
- AVCL – this is the air and vapour control layer.
- WFRL – the water flow reducing layer (on inverted and some green roofs). This reduces the amount of water flowing down to the waterproofing, warming and flowing into the drainage system. Thermal loss can be reduced and managed by a properly installed WFRL.
It is no longer acceptable for a main contractor to provide roof decks with back falls, large depressions or non-draining areas. In order to achieve a zero fall finished surface, a design fall of 1:80 should be used, with a comprehensive structural analysis that covers construction tolerances, settlement and deflection under load. Any sites with negative falls which will hold water will need to be rectified before the roofing material is applied. A roofing contractor will need a flat and properly drained surface on which to lay the specified roofing system for a project and the finished roof should not suffer from inadequate drainage or ponding.
We’ll have more information next week on BS 6229:2018 so that our readers are kept fully informed of the changes in Standards which impact our industry. Don’t miss out on this – follow us on Facebook or Twitter for a heads-up when the article is published.