loft conversion dormer exterior window

Loft Conversions Wales

L-Shaped Loft Conversions

Maximising your space to an L-shaped loft conversion can significantly add value to your property.

It’s a superb investment for your home that prospective buyers look for. 

We have a wealth of experience in completing this style of project due to the housing styles of areas like Llanishen and Lisvane in Cardiff and so we can confidently deliver the living space your house shape is best suited to.

What is an L-Shaped Loft Conversion?

An L-shaped loft conversion involves either two dormers, mansards or hip-to-gables joined together to form an L-shape. There are three common types of L-shaped loft conversions detailed below:

01 L-shaped dormer loft conversion

02 L-shaped mansard loft conversion

03 L-shaped Hip-to-gable conversion

l shaped loft conversion
L Shaped 1
Most people Need a point in the right direction
Not sure where to Start?

L-shaped Dormer Loft Conversion

An L-shaped dormer loft conversion is an extension where two dormer loft conversions are joined together to create more space. To create a unique L-shaped dormer loft conversion, a dormer must be constructed on the main roof and connected to the other dormer on the existing roof of the rear extension.


This type of loft conversion is popular and considered the best way to extend mid-terrace properties to maximise space of around 40m³.

L shape Dormers are similar to a rear dormer conversion, with a 90 degree angled wall, but it has an additional room above the rear addition/outrigger.

Property types

It perfectly suits Victorian and Edwardian Houses where there is a rear addition to the back of the property. Its structure allows the dormer to be extended in that area.

It’s also used where properties have extended above their garage already and are looking to elevate that space.

L-shaped Mansard Loft Conversion

An L-shaped mansard loft conversion looks similar to a rear mansard conversion with a 70 degree angled wall and additional space for more rooms at the rear addition/outrigger.


An L-shaped mansard loft conversion looks similar to a rear mansard conversion with approximately 70 degrees angled wall and additional space for more rooms at the rear addition/outrigger.

Property types

This mainly suits Victorian / Edwardian houses & flats because of the presence of the addition or outrigger at the rear side of the property. It works perfectly for a loft with an open-plan bedroom and a fabulous ensuite.

Kitchens and bathrooms are often placed at the rear of the property, which makes it possible for the mansard to extend over the area.

L-shaped Hip-to-gable Loft Conversion

This is a type of hip-to-gable conversion, but with a twist. It forms an L-shape and, just like the hip-to-gable loft conversion, is done by extending the side roof  to turn the hipped roof into a vertical gable roof.


It’s also an excellent way to maximise your loft and achieve more space for one or two bedrooms with a bathroom or home office.

Property types

There are many options for the customisation of your new space, such as:
– Extra bedroom
– A study room
– A separate bathroom
– Nursery room
– An office
– An ensuite or
– Dressing room

The Big Reasons
01/ Maximise

If your family has grown in size or you want space for an office to work from home, building an L-shaped loft is a good option. It can give you as much as 20m² in extra space.

02/ Value

Moving to a bigger house can be an expensive and stressful experience, not to mention the refurbishment that may cost more than you anticipate. A well-designed loft conversion can add value to your property, so it'll be more attractive to various potential buyers. It is often a better choice than moving into a bigger property and, if carefully planned, your L-shaped loft conversion can be an excellent investment.

l-Shaped Attics

Factors to Consider
Type of Property

Since L-shaped loft conversions require a rear extension to form the L shape, it is only suitable for selected types of properties.  Usually Victorian and Edwardian terrace and end-of-terrace houses are good options for this type of loft conversion because these types of houses provide an addition to the rear of the house, which creates the L-shaped roof.

These existing rear extensions on terraced homes were designed and constructed to provide a ground floor kitchen and a first-floor bathroom or ensuite. Therefore, the rear roof area is a popular and excellent choice for a shower room or an ensuite bathroom.

Existing plumbing, like the soil pipe, can be tapped cost-effectively. An l-shaped loft conversion is also an ideal way to acquire additional space in a property with limited space for a garden, as going up into the loft means not having to lose vital garden space to a ground floor extension.

Planning Permission

Most of the L-shaped dormer loft conversions don’t require planning permission as long as they follow the 40/50 cubic metres rule. This rule under UK Permitted Development states that the maximum space permitted for terraced properties is 40 cubic metres and for semi-detached and detached homes is 50 cubic metres.

However, local authority planning policies vary, so it is vital to check the rules with your local planning office and your loft conversion specialist/company; especially if your property’s location is in a conservation area or the proposed site is facing the road or other properties, as this could make the application for planning permission necessary.

Whether the planning permission is required or not, the construction still needs to adhere to the permitted development to ensure that it complies with the regulations and you will be able to obtain certification for compliance once the works have been completed.

Usable Space

It is essential to check if the roof space suits a loft conversion. If it is deemed ideal or suitable for a loft conversion, thorough planning and decision-making about design and potential floor plan would begin. All of the design options – which includes multiple rooms, size, fixtures, fittings and stairway – will be considered. However, it will depend upon the budget available, the type of accommodation needed, and any other desired features such as a Juliet Balcony.

For a terraced or end-of-terrace property to be considered fit for an L-shaped dormer conversion, the following standard must be met for the design:
– The larger or almost flat roof dormer must be built across the width of the rear of the main roof. This dormer could extend around, and over the additional rear roof area.
– An additional almost flat roof dormer must be constructed into the rear roof area. It does not necessarily extend across the whole width of the rear roof because it would take the loft conversion beyond the 40 cubic metres which is allowed under permitted development.
– If necessary, the design could be swapped around, still subject to planning regulations. The full width of the rear roof can be used for the majority of the dormer. The smaller end of the dormer can also be constructed into the main roof.
– The loft can have Velux windows to allow additional light across the extension if necessary.
– The appearance of the roof generally looks flat, but most lofts with this type of conversion incorporate a gentle slope to allow the water to run off rather than to collect and deteriorate the roof area.

Construction Timescale

Just like any loft conversion project, the timescale depends on different factors, including whether you are choosing to work with a one-person building company or with a specialist loft company. Working with a professional team helps to ensure that the planning and construction adhere to the planning requirements and complies with the professional standard. It also means that, with the teamwork of the members of the loft conversion company, the work is quick and efficient. Since multiple rooms will be constructed, this type of loft conversion could take 6 to 12 weeks, depending on the configuration and other relevant factors.


If you have any specific queries please contact us through  the form below.

L-shaped dormer loft conversions generally don’t require planning permission, but it must comply with the permitted development rules. However, requirements vary from place to place, so we recommend checking your Local Authority’s planning policy requirements before proceeding.

The average cost of L-shaped loft conversion is estimated around £45,000- £60,000, but it can vary greatly depending upon the size and also with the complexity of the property. Fittings and fixtures can also affect the price.

For traditional roofs, the minimum height is 2.2 to 2.4 meters while for the modern trussed roof, the minimum head-height is 2.4 to 2.6 meters.

An L-Shaped Gable Loft Conversion is also abundant with natural light and skylight through window’s access.

The usual build time for L-shaped dormer, mansard and hip-to-gable conversion is 6-12 weeks.

Or Just Ready to Get started?
Our Contact
Email Address

Call Us

029 2252 0162