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The Daily Insight

What does rear dormer mean

Author

William Taylor

Published Apr 08, 2026

A rear dormer extension is the process by which the back slope of the roof is removed and then built up into a box shape from the rear elevation. Rear dormers are usually built off the back wall and up off both the sides.

What is a rear dormer window?

The back existing slope is removed and built up vertically from the rear elevation. Rear dormers are sometimes built directly up from the property’s back wall or, in some cases, they are stepped in slightly to ensure the loft conversion adheres to the local council’s regulations.

What is the difference between a loft conversion and a dormer?

A rear dormer conversion is the most typical Loft Conversion carried out. … A rear dormer conversion allows you to keep a sloped roof at the front where Velux windows can be fitted to allow natural light to pour in. The rear dormer is an ideal way to create more head and floor space at the back of the attic.

Does a rear dormer need planning permission?

Rear dormers may not always require planning permission. It is always recommended that you check with the Development Control Team before starting any works on a dormer extension.

What is the purpose of a dormer on a house?

Dormers are commonly used to increase the usable space in a loft and to create window openings in a roof plane. A dormer is often one of the primary elements of a loft conversion. As a prominent element of many buildings, different types of dormer have evolved to complement different styles of architecture.

Can I put a dormer in my roof?

On the whole, any home with a pitched roof and loft space can add a dormer. Flat roofs can also create a loft addition, but this wouldn’t be classed as a dormer, and so is a topic for another day. Because they create new headspace, dormers are perfect for lofts that are just that little bit too small.

What is the difference between a dormer and a mansard?

The only difference with a mansard is that the slope across the face of the mansard will make the construction look softer from the outside. It will, however, sacrifice some head height compared to a dormer that is built vertical off of the back wall.

Can I put a dormer on the front of my house?

Dormers are usually added to the rear, but subject to planning permission, they can be added to the side or front of your property.

How much does it cost to put a dormer on a house?

It typically costs between $2,500 to $20,000 for professional dormer installation, or about $115 per square foot. There are several options for dormers, including shed, flat, gable and hip. Smaller projects, like adding a window dormer, cost about $4,000. Larger remodels like adding a bathroom dormer run about $24,000.

How much does a dormer loft conversion cost?

The average price of a dormer loft conversion is currently sitting around the £45,000 mark. Most people in the UK pay between £30,000 and £60,000 for their loft conversion in total. The cost breaks down into several chunks. Some of the money you pay goes into planning.

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How far can you extend without planning permission 2021?

How big can you build an extension without planning? The permitted development rules have recently been relaxed, allowing you to build an extension without planning permission of up to six metres (or eight metres if your house is detached).

What can you build on land without planning permission?

Outbuildings such as sheds, garages, greenhouses and some other structures are also considered to be permitted development. You can build a garage or outbuilding on your property without planning permission as long as it’s of a reasonable size – no higher than 4 metres.

What are shed dormers?

Shed dormers are often horizontally proportioned and cover large portions of a roof to open up an attic for more usable space. Like other dormer types, they can either be an extension of the wall below or an object set in the roof.

How much value will a loft conversion add?

As a guide a well built and perfectly appointed loft conversion can add between 10–20% to the value of your home, according to Ideal Home.

Do I need permission to do a loft conversion?

Most straightforward conversions won’t need formal planning consent. Instead, many projects are allowed under what’s known as permitted development (PD) rights – often even if you’re adding a modest amount of extra space via dormer windows.

Are dormers worth it?

There are several good reasons for a roof dormer: Dormers add architectural interest, accent, and detail: Having one or more dormers as part of a roof’s structure can boost the curb appeal of a home that might otherwise be a bit bland. … Dormers have an average return on investment or recouped value of 65-70 percent.

How do dormers work?

Located on the sloped side of a roof, a dormer window brings natural light into an attic, loft, or any room with a vaulted ceiling. This type of window sits vertically in a framed structure that juts outward from the pitch of the main roof and features a little roof of its own above the window.

What style of house has dormers?

From the outside, a dormer can define certain house styles—Neo-colonial and Colonial Revival, Stick Style, Chateauesque, Second Empire, and the American Foursquare are all house styles that generally include a dormer in their designs.

What is a loft dormer?

Dormer and l-shaped dormer loft conversion A dormer loft conversion is an extension to the existing roof that projects vertically from a sloping roof, creating additional floor space and headroom within the property. Internally, a dormer has vertical walls and a horizontal ceiling.

What is the purpose of a mansard roof?

Developed in the 16th century but named from 17th-century French Baroque architect Francois Mansart, the mansard roof lets designers turn an attic into a livable space by increasing up the volume of the interior. The style can be found around the world, but the mansard roof is most associated with France.

What is an L-shaped dormer?

An L-shaped dormer conversion is where two dormer builds are constructed in a way that they join together. Usually one dormer will be built on the rear outrigger roof and the other on the main roof, which is what gives it the instantly recognisable L-shape.

How long do dormer roofs last?

2 Answers from MyBuilder Roofers Fibreglass – 25 years plus. All of course dependent on workmanship and degree of weathering the roof gets (shaded roofs may last long).

Can you have two dormers?

Can I have two Dormers? Sometimes it’s possible to have two dormers built as part of a loft conversion, which will really maximise the space in your loft. This can work particularly well if you have one dormer to the front or rear of the property, and one to the side.

How much space can a dormer add?

Adds more space – Perhaps the main benefit to installing dormers is the space it can add. Because dormers extend a wall or extend away from the building, they can add up to 250 square feet of space to a room.

Can you put a bathroom in a dormer?

Bathroom dormer additions can be an effective way to gain some extra square feet and headroom to put in a small bathroom in an otherwise tiny area. However, bathroom dormer additions can be complicated, and thus expensive to do. Below are some important topics to think about when considering a bathroom dormer addition.

How long does it take to build a dormer?

Dormer conversions – 5 weeks on average. Hip-to-gable conversions – 6 weeks on average. Mansard conversions or full roof replacements – 7-8 weeks on average.

Do dormers leak?

The leak is usually caused by flashing around the dormer area being improperly installed or nonexistent. The best way to repair a roof leak around a dormer is to use step flashing. … Step flashing is a structural metallic barrier between the walls of the dormer and the roof.

Can my Neighbour stop my permitted development?

Can neighbours stop permitted development? Property under permitted development does not require planning permission, meaning the public, and neighbours, typically cannot object to the development.

Can Neighbours stop loft conversion?

You do not normally need permission from your neighbours for your loft conversion, nor Planning Permission from your council (as loft conversions are usually counted as “Permitted Development”, but you may need to have a Party Wall Agreement if the project is in a terraced or semi-detached property.

What's the cheapest loft conversion?

Roof Light Conversion A roof light loft conversion is the easiest and most affordable type of loft conversion. These types of loft conversion are quite basic. They only consist of reinforcing the attic floor and adding windows.

How much would a dormer cost UK?

How Much Does a Dormer Window Cost? A dormer loft conversion in the UK can cost anything upwards of £20,000 or around £500 – £600/m². The cost for a master bedroom loft conversion, with an en suite will naturally sit at the higher end of the spectrum at around £35,000 – £45,000.