Caution! Some acrylic roof domes may not comply with UK Building Regulations for fire spread.
Primary Authority rulings allow businesses to receive assured advice on regulations such as environmental health, trading standards and fire safety. According to The Primary Authority only polycarbonate domes, which are supplied as standard with Solatube sun pipe systems, meet the strict fire spread requirements as set out in UK Building Regs.
The following points clarify 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.
Does it matter what material the roof dome is made from?
Yes, 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.
What restrictions apply to the use of roof dome materials such as polycarbonate or acrylic?
All materials used on roofs must have a classification and there is a minimum requirement for thermoplastic roof lights, (Class 3 or European class D-s2, d2). Unclassified materials are automatically deemed non-compliant and should not be used.
Polycarbonate domes: 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. All Solatube polycarbonate domes are Tp(a) rated and can therefore be installed safely.
Acrylic domes: 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 determines if the acrylic dome can be used in the UK and if any restrictions apply.
Therefore any system using an acrylic dome must have a fire performance test and classification in order to be fire-safe.
Always ask to see a copy of this if the dome is acrylic.
How do I ensure the product already in my home, or about to be installed, complies?
Ask your supplier for the roof dome material classification. They should provide you with either:
- • 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 that the product complies with UK Building regulations and it could be a fire spread risk.
Click here for the document.
Other important considerations
Acrylic has a higher light transmittance than polycarbonate (it allows more light to pass through it). This allows some manufacturers to claim that their systems are brighter, even though they are using a material that is not approved for use in the UK.
Solatube could, and can if requested, also supply an acrylic dome which would achieve the same light transmittance. However, instead they chose to supply as standard a polycarbonate dome because it complies with UK Building Regulations and is a safer choice, ensuring that fire spread risk is minimised.
*The requirements regarding external fire spread can be viewed full in the HM Government Fire Safety Approved Document B4.
**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.