Rooflights may be defined as translucent or clear structures designed to be used on low or flat pitched roofs, in order to allow the natural light into a building while also maintaining the integrity-of the building-envelope. A wide variety of roof light systems are available in the market place, offering a wide-range of characteristics suiting different building types.
Types of roof light available
There are many designs available today. They can be categorised under their materials-of manufacture:
Glass offers the rooflight-specifier a great wide range of different options in regards to performance, aesthetics and function. Glass is usually preferred for domestic, commercial & retail applications, where the aesthetics, high performance & long working-life are major considerations. Glass manufacturers develop products which satisfy some of the most demanding-requirements, from all types of sophisticated active-solar control, to self cleaning properties & high impact-resistance. Glass has great fire properties, great impact performance, high light transmission & provides a mark against which optical clarity-of all the other glazing-media is commonly compared. It’s widely acknowledged-as having a really long life expectancy without discolouration from U-V degradation, & the laminated versions offer good levels of reduction in UV-transmittance. Glass can be curved to be used in barrel vault-rooflights & supplied with coatings, interlayers & surface treatments so as to provide textured or coloured surfaces in order to achieve diffused or obscure glazing, solar-control & total U.V protection to the areas that are beneath the glazing.
Modern thermoplastics such as Polycarbonate, have been well developed to give excellent performance in roof-lighting-applications. Polycarbonate is a versatile-material used extensively as roof light-glazing. It has 3 sheet forms: Solid, flat, cold-bent or formed, Profiled and Multi-wall.
The main properties of polycarbonate include; exceptional impact resistance, a high level of light transmission, a good workability and a good fire rating. They are all commonly available in tinted and clear options, with the clear & most tints providing direct-light, while the clear patterned & opal tint providing diffused-light & give a soft quality-to the light. Coextruded UV-protection eliminates about 99% of UV-radiation, thus protecting materials & people beneath. Each of these forms also has its’ very own particular characteristics & properties.
Solid polycarbonate provides good optical clarity & superb workability. It may be cold-curved on site & is suitable for-use with a number of glazing-bar systems. Polycarbonate rooflights can be formed into 3D-shapes, making it an ideal choice for pyramids, domes and barrel vaults.
Profiled polycarbonate will match profiled roof-cladding & will allow the sky to be seen easily through the corrugated material. This feature is quite popular with most designers. It also has a good profile accuracy & is available in growing profile range. Both extrusion & vacuum forming techniques enable a wide variety of profiles be produced.
Multiwall polycarbonate is basically an insulating glazing-material. Thicker sheets which have more walls obtain the highest thermal-performance, typically 1.6-W/m-2K for a 25-mm 5 wall sheet. The structured polycarbonate is usually used in many domestic & various commercial conservatories. Just like the solid polycarbonate, it can be cold-curved on site, though to a lesser degree. It’s also used in numerous glazing bar systems, & has a really high strength-to-weight ratio which makes it ideal for creation-of glazing features..