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Dome Materials Explained

Polycarbonate versus acrylic domes, does it matter? The domes, or roof covering, of solar tube systems are mostly made from one of three different materials; acrylic, polycarbonate or glass. Whilst each of these materials has its advantages over the others in various applications, glass for example will always be the best option for windows, when it comes to tubular daylight systems acrylic is the clear winner.

The role of the dome, or panel, is simple. It needs to keep the weather out and let the light in, and keep doing this to the highest standard.

Polycarbonate vs acrylic domes datasheet
Solarspot D-25 acrylic vs Solartube polycarbonate yellow roof dome -




Suitability for use in tubular daylight systems

Excellent resistance to UV yellowing and the best light transmittance.

Poor light transmittance and rapid UV deterioration make it unsuitable for this purpose.

Addition thickness for strength results in significant light loss making it unsuitable for this application.


Suitable for all domestic installations and most commercial.

Suitable for all domestic installations and most commercial.

Suitable for all domestic installations and most commercial.

Fire Rating

Tp(b) rating so suitable for all roofs of timber construction and roofs where specific fire regulations don’t apply*.

Tp(a) rating so suitable for all roofs of timber and metal construction.

Tp(a) rating so suitable for all roofs of timber and metal construction.


Meets all European standards for impact resistance.

Meets all European standards for impact resistance.

Can meets all European standards for impact resistance but needs to be much thicker than acrylic or polycarbonate.

Light transmittance

Best light transmittance of any materials.

Poorest light transmittance of all three being 10% worse than acrylic.
Not as good as acrylic. Additional thickness required for glass means a significant amount of light is lost.





* There are no specific building regulation for tubular daylight systems and no fire regulations that apply to roofs in general terms. And when you consider that the vast majority of roofs in the UK are constructed from timber, a full-flammable material, you will understand why. Without going into 200 pages of detail, unless a roof is also deemed to be a fire escape route, or there is a planning proximity stipulation as part of the planning requirement (and even then other factors may make this irrelevant), then there should be no reason acrylic is deemed to be unsuitable. If you would like more information and clarification on a specific project we will be happy to help.

Whilst it may seem that all three options may seem to have their merits, two options have such severe draw backs that it makes them both unsuitable for the application when you consider the purpose of the product.

Solartube Polycarbonate dome - turned yellow due to UV rays

Polycarbonate Domes

Polycarbonate starts with a massive disadvantage and that is because it is a poor transmitter of light, reducing the amount entering the top by around 10%. The situation is exacerbated further as Polycarbonate is so unstable when subjected to UV (daylight) that is goes cloudy and yellow in a matter of a few years – further reducing the input by another 10% (source: BRE – Solatube polycarbonate dome deteriorated a further 10% in just 4 years).

Read the BRE Summary Report
Light way glass dome, very heavy and not very good at transferring natural daylight

Glass Domes

Glass may seem like a good option, it has a good light transmittance and won’t go yellow, in order to be strong enough to withstand the rigours of conditions on the roof. To give a glass dome the strength it needs it is moulded to a thickness roughly four times that of acrylic or polycarbonate. The result of this additional thickness of glass is a corresponding increase in the amount of light absorbed by the dome. In fact, roughly 50% of the available light that could be entering the tube is blocked out.

Acrylic Domes

Acrylic on the other hand ticks all of the boxes. It has the best light transference of any material, it doesn’t deteriorate when exposed to UV and it’s very strong. And unless you have a really unusual set of building condition to conform to, there are no building regulation restrictions to worry about.

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