Your Guide to Dormer Windows

Would you like to transform your dark roof space into a bright, airy and liveable space? Dormer windows that protrude from the roof can certainly provide a suitable solution.


10 Jun 2024


Simon McAuliffe

Dormer windows



It is a word we love because it elicits an attractive idea of value through transformation. The best bit, however, is that potential is much closer than you might think. In fact, depending on where you are reading these words, potential is likely to be right above your head.


We are, of course, talking about the roof space of your domestic or commercial property. Anyone who has retrieved Christmas decorations from their loft or has clambered up there to store unnecessary computer equipment will know that the space is often severely under-utilised. With some clever architectural modification and the addition of gorgeous glazing, however, your roof’s interior can become a luxury living area, a bedroom with a view over the surrounding landscape, a bright and airy staff kitchen, or simply a relaxing retreat in which to unwind.


To achieve your vision of style and comfort, dormer windows provide an excellent solution. They are often the principal components of a loft extension, installed into a pitched roof to provide the occupant with additional space and plenty of natural light.


In this guide, we hope to outline the benefits of installing dormer windows and advise on whether you require planning permission to install them. To start with, it’s important that we have a definitive understanding of what a dormer window is.

What is a dormer window?


A dormer window is a roofed piece of glazing that projects vertically from the plane of a pitched roof. The word comes from the French word ‘dormir’ – ‘to sleep’ – illustrating the fact that the windows originally allowed a loft to become an additional bedroom when space was at a premium.


While the basic principle of a dormer window has been around since the 16th century, its style can vary immensely, to include flat-tops, hip-roof dormers, gable-fronted dormers, and even eyelid dormers whereby the window just peaks out from the tiling. Much like the style you choose – which will largely depend on your budget and taste – the reasons you might install such a piece of structural glazing are equally varied.


Why would you install dormer windows?


There are plenty of reasons for installing a dormer window into the roof space of your home or commercial property. For some people it is the opportunity to utilise an area that is currently purposeless; for others, the installation of dormer windows might be caused by an over-reliance on artificial light sources and a desire to bring in something a little more natural. Below, we explore four of these reasons in a little more detail.


Increased space

This – the desire for more space – is arguably the biggest reason for anyone to install dormer windows into the roof space of their property. The traditional pitched roof has a central portion where the occupant can comfortably stand up. Its edges, to the sides of this central area, either require a crouched position or are simply not accessible for most people. Dormer windows, therefore, provide additional headroom, significantly extending the useable space comfortably available in your loft or attic.


It goes without saying that by increasing the useable space in your home or commercial building, you are also increasing its value. Depending on the size and condition of the property (and who you ask), adding dormer windows can increase its value by as much as 20% – although we recommend speaking to valuation experts to determine the exact figure.


Increased natural light

We have written plenty of times about the many benefits of natural light. After all, studies suggest that it makes us happier, healthier, and even more productive. In our day-to-day lives, however, a survey conducted by the British Safety Council found that the average person is indoors for 90% of the time. If that statistic is anywhere near accurate, it is vital that we are still able to access the beneficial sunshine even within our four walls.


A dormer window presents the perfect opportunity to access natural daylight in what would, ordinarily, be a pitch-black space (the loft). As a result, you can reduce your artificial lighting costs, improve your physical and mental health, prevent sunburn, enhance the colours and textures of your interior design choices, and even enjoy sunrises and/or sunsets for longer than you would at lower heights.


You will struggle to find more enthusiastic proponents of natural light than us. Dormer windows, alongside skylights and even extensive glass roofs, are a great way of bringing beneficial natural light into a space, making it far more inviting, comfortable and practical than artificial lights alone – no matter how nice they are.


Improved ventilation

According to the World Health Organisation, approximately three million deaths were attributed to household air pollution in 2022. While the UK makes up a very small proportion of these, governance of indoor air quality still plays an important part in the country’s building regulations – specifically Approved Document F. When altering an existing property or building a new one, you must ensure there is adequate ventilation to limit the ingress of pollutant particles from outside the property whilst also maximising the airflow to allow internal pollutants to exit.


By installing dormer windows – specifically, if you install more than one – you create an opportunity for passive ventilation (through vents in the windows) and provide adjustable openings through which air can easily flow. As well as being legislatively compliant, you are also minimising the risk of harmful mould development whilst also promoting specific benefits such as improved sleep and concentration.


Improved aesthetic appeal

As well as being practically very useful, the addition of dormer windows can also enhance the external and internal appearance of your building. Stood inside, you can enjoy views across the landscape that might not be accessible from lower levels and can retreat into these purpose-built nooks that will be the envy of any book lover or person who simply loves a cosy corner. From the street, however, dormer windows add architectural interest and charm to your home, breaking up the monotony of a plain roofline and creating a more dynamic and visually appealing exterior.


Do dormer windows require planning permission?


So long as the dormer windows do not exceed the height and width of the roof, you are unlikely to need planning permission before adding them. Instead, they are likely to fall under ‘permitted development’. That being said, there are often specific limitations that may require you to speak to your local planning authority – such as size limitations or whether your property is located within a designated conservation area. 

Dormer windows allow you to make full use of your loft space, transforming it from a pitch-black and forgotten area at the top of the property into a cosy, bright and airy living space for you, your friends, family or colleagues. If you are interested in adding dormer windows to your property, speak to our specialist team today.