How Much Does It Cost To Add A Dormer Window?

by | May 24, 2022 | House Extension | 0 comments

The addition of a dormer window can enhance the visual appeal of your home, while also adding height and increasing floor space. It can transform an attic into a light-filled room capable of absorbing lots of natural light. But you need to pay attention to the details when designing dormer window and its installation or planning dormer extension . Nevertheless, you have to pay attention to the details when you are designing dormer windows. In this article we are going to get around it, all need to be carefully considered. In this article, we are going to dive into the details about the dormer and the dormer window cost.

What Is A Dormer?

Dormers are built-in structures of either wood or brick that are designed to add additional space and head height to a loft conversion. This kind of loft conversion happens when the loft height is limited, or when you’d like to maximize the space in the loft for a purpose other than adding another storey, for example, if you’d like to create a comfortable home office without adding another storey.

What Is A Dormer Window?

But what is a dormer window? Dormers are vertical windows that have their roof. They are protruding from a pitched roof and usually have horizontal and vertical planes. The view from a skylight is better than a skylight since it offers views outside just like a conventional window and creates a greater sense of space. As with skylights, dormer windows allow light into the roof space or loft, but unlike skylights, they also allow more headroom to be utilized and allow the space to be used for other purposes. Dormers can be categorised in many different ways, with the roof type determining which kind of dormer they are.

Types Of Dormer Windows

Wall Dormer

Various types of dormer windows including gabled, shed, hipped, and eyebrow, each adding character and functionality to architectural designs.

Dormers on a wall are structures whose vertical transverse plane shares the horizontal transverse plane of the wall. The gable end of a wall is incorporated into the structure of the building, doing away with the eaves. They don’t add much aesthetic value to a house since they aren’t common dormer types. The bigger windows on modern homes also allow for lots of natural light to enter inside. The larger windows are in essence extensions of the wall to the roof. It is because of this that they are seen as a wall element on the roof that appears vertically extending rather than being part of a wall.
The wall dormer is typically associated with older buildings and is usually smaller than the main course. Since they are belonging to the eclectic assemblies of these structures, they are an important part of the style itself.

Barrel Roof Dormer

A Barrel Roof Dormer: A unique architectural feature with a curved roof, adding character and charm to the building's exterior.

Another type of dormer windows in London is a barrel or arched roof dormer window. It’s easy to identify the dormer’s rounded or arched top by observing that each side and the front of the dormer have some wall space left. By adding this soft touch of colour, one can put some soft contrast against mostly harsh, straight lines that are seen on most sloped roofs. Due to the way that it separates the roof from the structure below, it is also known as a segmental roof dormer. It is more usual to build barrel roof dormers for aesthetic purposes as opposed to any specific use or function that they might have. As a result of the large size of their windows, they let in a lot of light, but their size makes them smaller than most other types of dormers. Since they are an uncommon type of dormer, you cannot just build them on top of a gable or a flat roof, so they will be more expensive to build.

Shed dormer

A shed dormer, an architectural element protruding from a sloping roof, adds space and light to a room with its window.

A shed dormer, a large dormer window is a type of dormer with only one roof plane and a much shallower pitch than the slope of the main roof. Sometimes, when reassembling a shed dormer, the pitch is so slight that it almost looks like it is horizontal. Water must run off the dormer to prevent it from catching on its roof.

Eyebrow dormer

A small dormer window with a curved roof projection resembling an eyebrow, adding architectural charm and character to the building's exterior.

Its roof design differs from a flat dormer roof by having a gently curved surface that extends completely above the window, instead of a flat surface. In contrast, the eyebrow dormer has no additional walls on either side. This can give the impression that the eye is peeking out from underneath the hooded outer eyelid.

How much does it cost to add a dormer window?

Dormer windows can transform a cramped, dark space into something brighter and more spacious if you are planning to upgrade or renovate your loft or attic conversion. Dormer window prices typically range from £600 to £1,200 for a single window, reflecting the wide variety of sizes and types of windows available, as well as the wide range of options in materials available. The cost to add dormer windows may vary according to the type and area of installation.

Cost breakdown

Below is a rough breakdown of dormer window cost


The costs here usually range from $300 to $600 and usually include the frame as well as the outer casement of the entire unit, as well as the actual glass pane


The cost of scaffolding lies anywhere between £250 and £350.


Depending on the scope of the project and the number of windows to be installed, a dormer window installation can most usually be completed in one day, but the time it will take will depend on what number of windows you want to have installed how big the window space is. It shouldn’t cost more than £350 to hire a contractor because most charge between £150 and £200 per day for labour.

Planning Permission To Add Dormer Windows

Once you are aware of a dormer window cost, you must consider whether you require planning permission or not. Normally, dormer windows at the front of the home would require planning permission, but dormer windows at the rear are usually permitted development, and therefore, may not require a formal application to the local planning authority. It must be noted that to stay within PD requirements, no part of the dormer has to exceed the top of the existing roof. As well, the dormer cannot project more than 15 centimetres forward from an existing roof slope facing a roadway or an elevation on a side of the house.
As planning authorities vary, it’s necessary to fully understand whether you need planning approval for proposed alterations. Any type and size of dormer windows you wish to install on a listed building or in a conservation area will require planning permission.

Bottom Line

While planning for dormer window installation, you must know dormer window cost and other factors that may influence the cost.

Emmanuel Nwaebo

Emmanuel Nwaebo is the Managing Director at Powerpillar Ltd and has more than 25 years experience in building construction and renovations. He has a bachelor’s in Electronics and Electrical Engineering with certification in Construction Health and Safety Technician (CHST). With an experience in managing construction and renovation services for years, he is extremely passionate about property management and loves helping people find their dream property.

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