This news item aims to clarify for the consumer the UK Building Regulation requirements regarding external fire spread for Tubular Daylighting Systems (TDS) with thermoplastic roof domes. The requirements regarding external fire spread can be viewed full in the HM Government Fire Safety Approved Document B4.
Q: In the UK, does it matter what material the roof dome is made from?
A: Yes, it does matter because the roof dome replaces a part of the roof covering and specific UK regulations apply in this event to ensure the integrity of the roof is not compromised in the event of a fire.
Q: What restrictions apply to the use of roof dome materials such as polycarbonate or acrylic?
A: All materials used on roofs must have a classification and there is a minimum classification requirement for thermoplastic rooflights
(Class 3 or European class D-s2, d2); unclassified materials are automatically deemed non-compliant and should not be used.
For Polycarbonate: With the exception of a protected stairwell*, polycarbonate classified as Tp(a) by an accredited authority has no restrictions in its use and may be installed anywhere in the home. Polycarbonate classified Tp(b) – a lower classification – would have restrictions in its use.
For Acrylic: Unlike polycarbonate, acrylic is a flammable material. Consequently, domes made from acrylic must have their fire performance tested to BS476 Part 3 in order to determine their UK fire classification. The resulting classification would then determine if the acrylic material may be used in the UK and, if so, the restrictions that apply.
*Protected stairwells are specially designed to provide virtually ‘fire sterile’ escape routes, from which flames, smoke and gases must be excluded by fire-resisting structures and/or an appropriate smoke control system. Consideration should also be given to Approved Document B2 (internal linings) for thermoplastic diffusers.
Q: How do I ensure the product already in my home or about to be installed complies?
A: Ask your supplier or installer for the roof dome material classification. They should provide you with an accredited material classification for the product supplied or a UK accreditation such as a BBA Certificate which confirms the regulations with which the product complies and its classifications. If your supplier cannot provide proof of the dome material classification, then you cannot be sure or prove that the product complies with UK Building regulations.