Dormer Loft Conversion

A Loft Conversion is one the best ways of increasing habitale space in your home, without the need to using space from your garden. Dormer loft conversions are particularly popular in UK's urban areas where there is a lack of space to go in the garden and only option is to go upwards. Improving your home instead of moving has seen a huge upswing in the recent years. If you are considering undertaking a Loft Conversion, you might have come across the word "Dormer", and wondered what is this exactly? And, more importantly, is the dormer conversion right for your house? 

What is a Dormer Loft Conversion?

A Dormer loft conversion is one of the most popular and commonly found types of conversion across the UK and it is perfect for a terraced or semi-detached house. A dormer conversion is when the roof is extended vertically thereby creating more headspace and floor area. If you see a box shaped strucuture added onto a pitched roof with its walls at 90 degree angle to the floor, this is a Dormer Loft. A Dormer conversion requires structural changes to your roof unlike a Velux loft conversion.

This type of loft conversion has minimal disruption, as it is carried out from the scaffolding outside your property. There are many types of Dormer loft conversions and which one will best suit for your home will entirely depend on the type of property (terraced, detached, semi-detached) and current roof size and shape.

It is regarded as the most common type of loft conversion for some reasons -

● Creates additional headspace and floor space 

● Cost-effective.

● No need for permission within specific conditions and limitations.


Different Types of Dormer Lofts in London

Dormer Lofts come in a different range of styles, shapes and sizes that suit every house. Our architectural and planning team will design your Dormer conversion to only enhance the look of your property but to boost its kerb appeal too. Our aim is to maximise the internal living space while ensuring the dormer is in proportion to the existing house. Here are the various types of Dormers...

Flat Dormer

Flat Dormer conversion is the most popular of all Dormer Conversions as these have a box-like structure with a flat roof to the rear of the property. Flat Dormer give the most internal habitable space and head height. On the contrary, they might not look as attractive from the outside, but the extra internal space makes it up for the lack of good looks. Just so that you know, there are some local councils in London that do not allow dormers so before you select the choice of your loft conversion, ensure you check the regulations with your local planning council. 

Gable Roof Dormers

The Gable Roof Dormer is the best loft conversion solution for terraced properties. This is also known as the dog-house dormer, which is a more complex conversion which requires the gable wall extension upwards to meet the current ridgeline, with a new sloping roof area also built towards the new gable end.  This conversion does not require planning permission. We simply work on the existing pitched roof in order to maximize space. By adding vertical windows, you increase the sunlight and space.

Hip Roof Dormer

The hip roof dormer is quite like the gable roof dormer in terms of the general structure; however, the actual roof layout is different. A hipped roof dormer is a conversion where the roofs slope on all three sides of the structure.  This conversion is attractive to look at but this type of conversion results in less internal usable space. Areas around the UK that are prone to high winds favor this type of loft conversion. Overall it is a complex conversion to construct due to the sloping plane.

Mansard Dormer

The Mansard Dormer is named after French architect Francoise Mansard. The Dormer is normally built to the back of the house, with a flat roof and the vertical sides often angling at 70 degrees. This sort of Dormer conversion offers maximum increase in floor space and is particularly suited for detached homes. 


Shed Roof Dormer

The Shed Roof Dormer is a similar conversion to that of the flat roof, the only difference being the angle at which the roof slopes down. The shed roof dormer has only a single sloping plane. It has no peak or hip, which reduces building cost. These are the best suited for properties of the Victorian era or homes with a gable roof.

L Shaped Dormer

The L shaped Dormer involves building two dormers, first one over the roof of the existing property and the second one above the rear extension. These 2 dormers meet to form the L shape. This type of conversion is popular with Victorian terraced houses. 

Arched Dormer

Last on the Dormer Loft Conversion range is the Arched Roof Dormer. This Dormer conversion has an arched roof and best suited for period properties of the Victorian era.



The right kind of Loft Conversion is influenced by 3 major factors –

  1. The type of roof you actually have right now
  2. The main purpose you want to use the loft for
  3. Your budget, yes!


The most important factor to consider when starting to think about converting the loft space within your home is your existing loft structure. You can consider a dormer if you have a pitched roof and loft space.


Planning permission is generally not required in most boroughs across London as a loft conversion is usually considered under permitted development, however it is subject to some limitations and conditions below - 

● Allowance of 40 cubic meters additional roof space for terraced houses*

● Allowance of 50 cubic meters additional roof space for detached and semi-detached houses*

● No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway

● No extension to be higher than the highest part of the roof

● Materials to be similar in appearance to the existing house

● No verandas, balconies or raised platforms

● Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor

● Roof extensions not to be permitted development in designated areas**

● Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves

● The roof enlargement cannot overhang the outer face of the wall of the original house.


  • Hassle-free construction with minimum noise and disturbance.
  • Dormer Loft Conversion London Doesn’t necessarily Require Planning Permission
  • No limitations to the options when it comes to style
  • This form of architecture allows you to optimize the space.
  • It also supports Installation of a Skylight
  • The vertical wall makes it easier for you to fulfill your ever needed storage space


There is no doubt that you will have to think about your property’s ceiling height when determining whether your loft is suitable for a loft conversion or not.  A traditional roof is about 2.2-2.4 meters high while a modern trussed roof has a minimum height of 2.4-2.6 meters. For a habitable space the preferred headroom level is 2.3 meters. This height need not be maintained over the entire floor area, and a lower height may be acceptable for a bathroom, hallway or kitchen. If your head height is lower than the above, this can be achieved by lowering underneath the floor ceilings.

Some commonly asked Questions about Dormer Loft Conversions

Do Dormer Loft Conversions Require Planning Permission?

In many cases, dormer loft conversions in London, do not require any planning permission as long as they are within the permissible development conditions of the type of property you have. Unless your house or flat is in the conservation area then different rules will be applicable for loft conversions.  Dormer conversions to the front of your home will require planning permission as they are overlooking the main road. We advise to always check with your local authority on whether your property will require planning permission or not. You can find more information and the relevant regulations here.

How long will a Dormer Loft Conversion take to complete? 

If all goes to plan and you have a standard loft conversion, a new Dormer loft conversion would take around 3-5 weeks for the structure and allow another 2-4 weeks for the finishing and decor. 

What other things do I need to look out for? 

If you own a terraced or semi-detached house in England or Wales, it is likely that that you will need a Party Wall Agreement from your neighbour(s). This is because your structural work will be going into the party wall for construction of the dormer. You need to ensure your loft conversion work complies with the local building regulations and you get approvals at every stage before moving forward. 

How much does a Dormer Loft Conversion cost?

This is a bit of a tricky question to answer especially when we have not seen your property. The price is highly depending on the size of the conversion, complexity and the extra work involved such as fixtures and fittings. On record, the average cost of a standard loft conversion starts at around £40k but our surveyor will first need to visit your house to discuss your requirements in detail before we can provide a detailed quote. 

How to get natural light into a Dormer Conversion?

In a Dormer loft conversion, you can get natural light coming in from the dormer windows (vertical) and the skylights too. If you have a bigger internal space, then you can add a Juliet balcony to get more light into your loft.

What are the sizes for a Dormer Loft bedroom?

Just like any other bedroom, Dormer loft bedrooms can vary in size and shape, some are just as how the normal bedrooms size or shape would be, however some are of unusual shapes especially when the chimney stack is present. 


A well built, high-quality loft conversion in your London home not only adds additional space for you but adds value to your home. Loft conversions can be perfect for a new bedroom, playroom, home movie theater or bathroom. Though, a poorly converted loft can not only minimize the value of your property, but in some cases can also compromise with your security and the structural stability.

Tell us about your Loft Conversion Requirements