Building Regulations for Skylights & Rooflights

What’s on top of your home improvement list? Residents in London are opting for increasing natural daylight, according to new research. Numerous studies have proved the benefits of increasing natural daylight in the home but what first steps do you need to take to realise this goal?

Natural light can be introduced into the home in a variety of ways, vertically through the use of windows which can be limiting and horizontally through the use of rooflights, and sun pipes. These horizontal applications will flood the room with more high quality light then the traditional window.

In these article we will talk about planing permissions and building regulations for skylights.

How to plan rooflights, skylights & sun tunnels in your home?


A ‘Rooflight’ is the most widely used term to describe windows installed into a roof, many presume the Velux style windows fitted ‘in plane’ or flush however these are generally referred to as roof windows, rooflights are often provided with an upstand for installation onto flat roofs. They can range from polycarbonate plastic dome rooflights to aluminium and glass versions which often carry a more premium price point but provide the nicest finish. Rooflights come in many shapes and sizes including dome, circular, pyramid and square.

Rooflights are offered in three main types, fixed, ventilation and access (opening).

Fixed rooflights are exactly that, fixed down to the frame and provide the most cost effective means of bringing light into the room allowing you to reduce your carbon footprint.
Ventilation skylights will enable you to let more air into the room and are ideal in areas such as kitchens and bathrooms due to the variable temperatures which can lead to condensation. Manual or electric operation are generally available and can incorporate rain or wind sensors.
Access rooflights provide easy access to a roof ideal for maintenance and repairs on the roof, it is also possible to use larger rooflights to provide access to a roof terrace or balcony.

Sun Pipes

Sun pipes are perfect for bringing natural light into rooms where windows or rooflights cannot reach, for example rooms situated in the middle of an upper floor. Natural light is collected from a dome installed on top of a roof (Think of it like a miniature rooflight). This dome is connected to a highly reflective silver tube which can be directed between rafters and roof voids to bring light into the rooms below. The Dome shape ensures light can be easily captured from all sides providing a surprising amount of light throughout the day.


Sun pipes and rooflights are fantastically diverse and can cater to a wide variety of needs however before ordering, consideration must be taken into account for these following points:


There is no hard and fast rule for deciding on the most suitable size for a rooflight, the Government Building Regulations recommend glazed areas should be equivalent to 10% of the room’s floor area to achieve adequate daylighting. This means for an average kitchen size of 100 square feet (9.2m²), a single 1200 x 1200 dome would be sufficient, (The tapered upstand means the structural opening is wider than the actual dome size, so a 1200x 1200 provides the effective light area of 1000 x 1000 dome) alternatively for a more evenly distributed lighting particularly for long and narrow extensions multiple smaller domes are recommended. If you allow for 20% of floor area then this will transform any room into a beautifully lit and welcoming interior space.


As dome rooflights are manufactured from polycarbonate they may not be as efficient as their glass counterparts, this is often reflected in the price. Quality glass rooflights can start from around £700 whereas polycarbonate start from £200. When choosing polycarbonate for a home it is recommended to always go for triple layers that offer a minimum U-value of 1.8 W/m²K to meet Government recommended thermal efficiency regulations.

Glazed rooflights come at a more premium price point and provide the best insulation and sound reduction, double glazed rooflights should always be offered with toughened and laminated glass.

Planning Your Sun Pipe

Top questions to ask yourself when looking at Sun pipes:

  • What type of roof have I got?
  • Is it flat or pitched?
  • What type of tiles have you got?
  • What length do I need it to span, are there any obstructions such as rafters or beams?
  • Always try to find the shortest possible route as the longer the run the less effective the sun tunnel is.
  • Where required, additional 45° elbows and angles are all available but the more you use the more they affect the overall performance so it is much more economical to find the shortest route
  • What room is the sun pipe going into?
  • Smaller rooms and short hallways only require the smaller sizes which are enough to allow safe passage without lights switched on, longer corridors, toilets and preparation counters in kitchens may require sizes between 300mm and 400mm while larger bathrooms, lounges and stairways benefit from sizes larger then 500mm. (Where the dimension refers to the diameter of the sunlight collector/Dome placed on the roof.)
  • Positioning the skylight or sun tunnel

It is a common misconception that in order to achieve the maximum amount of light a room needs to be south facing, however rooflights and sun tunnels collect light from all around (And most importantly from directly above). Due to the reflectance of clouds, direct overcast light from above is 3 times brighter then horizontal lighting!


Ordering Options

Addlite is the new online arm of bespoke roof access company, Surespan. Surespan have been trading for nearly 2 decades and are experts in the field. The online website provides easy and cheap access for everyone to rooflight products which are often very difficult to come by elsewhere.

Each product page has a list of available sizes which are all in stock for delivery within a few working days. For rooflights, the sizes shown refer to the opening that is required in the roof so you know exactly what needs to be cut by the roofers. Sun tunnel sizes refer to the diameter of the dome, the actual opening required may be between 10 – 20mm wider, however we would advise to refer to the installation instructions for further details.

Other options to choose from for rooflights include the choice of layers, these are the number of polycarbonate layers between the internal space and external space. The more layers the better insulated the inside rooms will be from the outside and vice versa. Layer variant provides the option for clear layers like a window or obscure layers which reduces the amount of glare transmitted through the rooflight which does impact on the overall light performance but produces a softer, slightly more diffused light.

Natural daylight comes with many benefits particularly in built up cities such as London, due to light pollution some might find it more difficult to sleep however if we introduce more natural light into our systems our bodies do not need it to be as dark when we sleep. 


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