With so many options available from so many suppliers, choosing the right rooflight can be a bit of a minefield. Here Paul Trace from Stella Rooflights answers the key questions you will need to consider when seeking out the ideal rooflight for your project, based on aesthetics and practicality

DO I NEED A PITCHED OR FLAT ROOFLIGHT? 

The design for a flat rooflight is different to that of a pitched rooflight and a flat version will require a kerb/upstand section built onto your roof. If you have a sloping roof you can generally find rooflights that can be installed between 17 and 70 degrees. It is always important to know the roof finish and mention the pitch of your roof when talking to rooflight suppliers, to ensure you are quoted for the right product.

HOW BIG CAN MY ROOFLIGHT BE?

Modern glazing technology allows some very big areas of glass to be achieved, but if you are working with an older or listed property then it is advisable to use conservation rooflights and keep to smaller sizes. More modern projects are better served by more contemporary skylight designs which have much larger areas of high specification glazing, without the more traditional glazing bars used in conservation roof windows. Just remember that the bigger the glass area the thicker and heavier the glass will be, so you may need to crane your rooflight into position.

DO I WANT IT TO BE AN OPENING OR A FIXED DESIGN? 

This will depend on whether you need the rooflight for ventilation or just for light. Having fixed rooflights quite often works out more cost effective because you can have larger pieces of glass without the overhead of the mechanisms. Some bespoke rooflight manufacturers can produce frames which combine both fixed and opening casements.

HOW WOULD I LIKE MY ROOFLIGHT TO OPEN? 

This will depend on whether you need ventilation or access to the roof. If you have other sources of ventilation then it is probably advisable and more cost effective to have a fixed (non-opening) roof light. Smaller rooflights tend to operate manually but if you opt for a large rooflight most will be operated with electric actuation. There are a wide variety of actuators available but typically a rooflight operates with a small cill mounted actuator to push the casement open. Larger bespoke rooflight designs can sometimes have concealed actuators to lift casements.

WHAT GLASS SHOULD I USE IN MY ROOF LIGHT? 

There is no ‘one size fits all’ option for rooflights, so glass specification should be chosen to reflect your most important requirement. There are lots of glass options available for example, double/triple glazing, self-clean, solar control or toughened safety glass. Many standard off the shelf products do not offer such a high level specification as standard, so make sure you are comparing like for like when getting quotes.

It is important to check with your manufacturer that they comply with the latest Building Regulations (expanded on further below) and that the thermal performance (U-value) quoted is for the whole frame, and not just the glass unit.

​WILL LOCATION AFFECT THE PERFORMANCE OF MY ROOFLIGHT? 

If your project is located near to the coast or in an area of high pollution, it can make a difference to the lifespan of your rooflight. This is particularly important if you are looking at installing a metal rooflight; always opt for 316L stainless steel. This may cost more initially, however you can be sure that your rooflight is protected, and will not rust. It is worth noting that mild and carbon steel rooflights rely heavily on the coating to prevent rust, so these are likely to require significantly more maintenance than a stainless alternative.

WHAT ARE THE RULES & REGULATIONS THAT APPLY TO INSTALLING ROOFLIGHTS?

The first thing to consider when installing rooflights is whether or not you need planning permission – especially if you live on an older property and require a conservation rooflight. In some cases, planning permission may not be required if the rooflights are not visible from the street and do not alter the external appearance of the building. However, it is always best to check with your local planning authority before proceeding with any installation work.

After this, the next step is to ensure that the rooflights meet the requirements of UK Building Regulations. The regulations that are relevant to rooflights include Part B (Fire Safety), Part L (Conservation of Fuel and Power), and Part K (Protection from Falling, Collision and Impact).

Part B (Fire Safety) requires that rooflights be designed and installed in such a way as to prevent the spread of fire. This means that they must be constructed from fire-resistant materials and that they must be installed in such a way as to maintain the integrity of the roof. If the building is listed, then it is important to consult with the local conservation officer to ensure that any proposed works are sympathetic to the building’s historic fabric.

Part L (Conservation of Fuel and Power) requires that rooflights meet certain thermal performance standards. This means that they must be designed to prevent heat loss and reduce the need for artificial lighting during the day. If the building is listed, it may be necessary to use specialist conservation rooflights which are designed to replicate the historic appearance of the original rooflights.

Part K (Protection from Falling, Collision and Impact) requires that rooflights be designed and installed in such a way as to prevent people from falling through them or being injured by them. This means that they must be strong enough to withstand the weight of a person, and that they must be designed to prevent people from slipping or tripping on them.

Paul Trace is a director at Stella Rooflights