What's the Maximum Size for a Skylight?

Adding a skylight to your property has so many great benefits, from enhancing the aesthetic appearance of a room to improved energy efficiency through increased natural light. When you are planning your rooflight installation, one of your main considerations is what size of skylight you want to fit.

You may prefer to add a series of smaller skylights in a room or install one larger rooflight. The higher the total surface area of the glass, the more natural light you will gain. We’re often asked how big can a skylight be? - and there is no definitive answer to this, as there are various factors to consider. The largest skylight size that most companies provide as standard is 1000mm x 2500mm but customised sizes will usually be available too.

From a manufacturing perspective, skylights can be made to pretty much any dimension but other factors such as the size of the room it will be installed into and the structural integrity of the roof will need to be reviewed. You will also need to consider building regulations when deciding on the size of a rooflight.

Take a look at our range of large skylights in various design options.

What determines the size a skylight can be?

One of the most important factors in determining the maximum rooflight size for a room is what is dictated by the UK building regulations. The regulations stipulate that the size of the roof window should not exceed 25% of the floor area, unless equal or lower carbon footprint can be demonstrated. The regulations also require the rooflight does not protrude more than 150mm from the existing roof plane, although planning permission might be obtained in some cases.

The roof structure and what weight of window it can safely support will be another key consideration. The type of roof you are installing the rooflight into will either be a flat roof, which is typically made from joists and decking, or a pitched roof, which will usually have rafters and may have trusses that provide additional support.

Flat roofs made from EPDM or TPO are easy to install rooflights into but may not be strong enough to support large, heavy rooflights. You should check the specifications of the rooflights and consult a competent tradesperson if you are not sure whether the structure is suitable to install large skylights.

Older properties may have signs of damage in the roof that should be rectified before installing a rooflight to ensure that the structure will support the load implications of a skylight.

Our skylight sizes

At Rooflights and Skylights UK, we have nine standard roof window sizes you can order:

• 500x500mm

• 600x900mm

• 600x1200mm

• 600x1800mm

• 1000x1000mm

• 1000x1200mm

• 1000x1500mm

• 1000x2000mm

• 1000x2500mm

We can also provide custom sizes to meet your requirements and you can get a quick quote for the size you are looking for on the website.

Roof lanterns are perfect if you are looking to maximise the light and add depth to the room. Our roof lantern sizes range from 1000x1000mm up to 2000x4000mm. When choosing a roof lantern, it is important to follow the guidelines in the building regulations to ensure that the height is not protruding higher than the allowed limit.

Choosing the right skylight size for your home

All of the details we have covered, including roof material and structure, floor size and building regulations will need to be considered when deciding on your rooflight size. If you would like any advice on choosing the best size and design for your roof, get in touch. We can discuss custom sizes or explain which sizes will best suit your home and roof type.

At Rooflights and Skylights UK, all our rooflights have a 10-year guarantee and are Made in Britain, manufactured to the highest standards. View our range to find the best size rooflight for your home.