Background on conservation rooflights
Although rooflights (or skylights) have been around for centuries, they became more prominent during the Victorian era as technology and building aspirations were stretched and roof glazing boomed. One of the most famous Victorian building projects was the Crystal Palace, which, in 1851, used glazing on an unprecedented scale to showcase just what could be achieved.
Mass-produced Victorian rooflights for residential use tended to be made from cast iron, and the earliest examples would have smaller, lighter panes of glass. This was partially down to limits of glass technology at the time but also because of excise duties, which were imposed on glass by weight in the mid-18th century.
 Low profile
Genuine conservation designs should be manufactured with slim clean lines and a low-profile to match the roofline. Most authentic conservation rooflights are manufactured from steel because it provides great strength while offering a slim profile and excellent glass to frame ratios. There are many types of steel conservation rooflights and for unrivalled protection and lifespan.
Some conservation rooflights are finished with real wood linings. American ash is the most popular choice, although other types of timber can be used. The use of real wood gives a neat, warm appearance to the internal element of a conservation rooflight.
While some rooflight suppliers use soft wood or plastic that is painted white as an internal finish, these liners can result in deeper frame profiles or reduced viewable areas. A white internal frame can be sold as ‘clean’ or ‘neat’, but these can sometimes produce a finish more often associated with modern flat rooflights than traditional conservation products.
Victorian rooflights would have been single glazed, however, modern building standards are much higher and so single glazing does not meet the minimum requirements for thermal efficiency (Part L). Double glazing is now the most popular option for genuine conservation rooflights because glazing technology is such that a modern double glazed unit can provide a number of benefits while remaining reasonably slender.
Some conservation rooflight suppliers offer triple glazing for improved thermal performance, it can come at the expense of appearance. With a flush fitting profile being one of the main requirements of a conservation rooflight, the introduction of triple glazing makes that almost impossible on some roof types.
Conservation officiers sometimes specify that a conservation rooflight should have a glazing bar to replicate that original Victorian appearance. It is not always the case, but it is definitely worth checking before making a purchase.
If a glazing bar is required, then it should be a genuine one. A genuine glazing bar should be something which not only divides the glazing but also provides additional strength to the casement. A stuck on glazing bar is one step up from a felt pen but certainly should not be seen as a way to make a modern bulky framed profile meet the criteria of a conservation rooflight.
 Top hung
A top hung profile not only offers a more authentic appearance, it maximises the space below because the casement doesn’t stick into the room. Smaller top hung rooflights also utilise beautiful brass ironmongery to operate the casement whereas centre pivot designs tend to rely on modern plastic handles, which are out of reach and offer nothing to enhance the internal aesthetics.
Just because something is sold as a conservation rooflight, that doesn’t automatically make it suitable for all building types. For listed buildings - or those in a conservation area - then the criteria for using conservation rooflights may be more strict. There are only a handful of companies that specifically make conservation rooflights and even fewer who design, manufacture and assemble in the UK.
With the UK Government pursuing a carbon neutral environment, it is imperative that every action is taken to reduce energy consumption. Rooflights are energy efficient as they let in large amounts of natural light thus reducing the need for artificial lighting.
With so many choices available, choosing the right conservation rooflight can be a bit of a minefield but with the right guidance and advice it need not be a stressful experience.
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