What is a Mansard Loft Conversion? An Ultimate Guide

by | Aug 30, 2022 | Loft Conversion | 0 comments

A loft conversion is the most common practice among the habitants of London . There could be endless possibilities to convert your loft. However, it depends on your choice of wat you want your attic to be like. One of the most frequent loft conversions is mansard. If you do not know what mansard loft conversion is or how you can plan it, don’t worry. We are here to guide you through the path of converting your loft. In this guide, you will get all the necessary information to get the work started, So let’s dive in!

What Is Mansard Loft Conversion?

When a mansard loft conversion is done, two pitches are provided to the sloping roof. The top of the roof slopes steeply than the sides, but the sides slope steeper than the top.

Most of these buildings have flat roofs or equivalents. You can install a dormer window to add an extra floor to your home.

Mansard roofs have sloping roofing on each side, with one slope being steeper than the other. Essentially, this means that your entire rooftop has been extended.

A loft conversion usually takes place at the back of a house. More space is created when one wall is removed, and the party wall is raised.

No less than 72 degrees is the vertical slope of the new roof.

Why Mansard Loft Conversions?

This loft conversion style provides more excellent space than other loft conversions and is more economical because it lacks structural reinforcement. A mansard loft conversion costs more than a Velux, Dormer, or hip to cable conversion because of the amount of skilled work required.


In the end, building costs depend on the type and size of the structure. To ensure you receive an accurate quote, the constructor will inspect your loft space before beginning any design work.

Can A Mansard Loft Conversion Be Done On Any House?

Many houses would benefit from mansard loft conversions, including detached and semi-detached structures, terraced properties, bungalows, and townhouses.

Modern semis to Victorian townhouses can all benefit from a Mansard conversion. It is common in areas with limited side and rear space or when homeowners don’t want to expand to the ground floor.

Mansard Loft Conversion Cost

The most important thing to ask is what could be mansard loft conversion cost?

Depending on the extent of the work, the conversion will cost more or less. More significant properties generally cost more. The type of finish and style you choose will affect the cost, and it will be more expensive to add a bathroom, for example. London architects or conversion companies will need to perform an entire costing exercise for each project.

Loft Conversions In Mansards

Mansard roofs are an aesthetically pleasing addition to all loft conversions. Unlike a traditional box-like dormer, this one looks like it flushes out the gable ends.

As a result of a mansard loft conversion, the roof slope is altered to 72 degrees. Terraced houses in densely populated areas are most suited to mansard loft conversions.

Generally, they fall into three categories:

  • The rear mansard
  • The front mansard
  • Rear and front mansards

Things To Consider


Does your roof have proper insulation? In the case of a conversion, this should be done in the middle. The loft is probably one of the warmest places in your house.

Insulation might reduce the importance of heating in loft conversions rather than cooling the loft in the summer. Summer is when it gets unbearably hot up there, whether you are sleeping or working.

Air Conditioning and Cross-ventilation

Cross-ventilation is a greener and cheaper alternative to air conditioning. For both temperature control and health reasons, your architect should ensure you have good ventilation in your loft.


If you’re planning a loft conversion, especially a dormer loft conversion, you should take blinds seriously. However much natural light we want in our homes, it is sometimes necessary to control it.

A loft with a west-facing dormer can be oppressive in the afternoons during the summer. Blinds that exclude glare without completely darkening a room are a better alternative to DIY store blinds.

If you use the room during the day, the blinds will also be opened and closed a lot, so pick ones with a long-lasting mechanism.


How does your loft look right now? There is probably everything you don’t have a home for. It’s a good idea to think about what you will do with all those things if you’re about to convert that space.

You may be in the right mindset for simplifying and going minimal, but don’t lose sight of the real world. Some things must be kept, and we’re not that ruthless in most cases. Getting your architect to design stores in your loft plans, or creating an area in your house where you can store your extra stuff, is the best option.

Do I Need Planning Permission For A Mansard Loft Conversion?

The roof structure of a Mansard loft conversion changes to a 72-degree angle, requiring planning permission. Depending on where you live, you may also need to meet the criteria for conversions to make sure they match neighboring properties.

If a planning permit is required, we can assist you in getting that permit.

Add a Mansard to your terraced or semi-detached home, and you may have to repair the party wall you share with your neighbors. Moreover, we can guide how to inform and secure the approval of neighbors before construction begins, ensuring a smooth, stress-free conversion.

Do I Need A Party Wall Agreement For Loft Extension?

Party Wall Agreements might be needed unless you live in a detached house. Consider your work’s impact on your neighbors’ walls before proceeding.

Other types of conversions, however, require their approval. A simple roof light conversion is unlikely to need their support. You can get advice from your architect.

Building Regulations For A Loft Conversion

The conversion of a loft or attic into a habitable space should be preceded by preparing the necessary plans, specifications, and calculations.

Please don’t skip this step by proceeding directly to construction to avoid getting fined!

How To Select An Architect For My Loft Conversion

Which factors determine the quality of an architecture firm?

When hiring an architect, it is essential to be confident that s/he has experience completing similar projects; you want to hire someone who knows their stuff. Please inquire about the obstacles your project will likely face and ask for samples of their previous work. You must have the same vision as your architect, even if you won’t be best friends.


It is also imperative to communicate effectively. Ensure you understand what your architect will share with you so that you can stay informed and make the right decisions. A good listener is crucial to the success of your project.

Pros Of Mansard Loft Conversion:

Some of the pros of mansard loft conversion are listed below:


Any structure will be valued more with mansard tops of various types. Their significance during the Renaissance was due mainly to their significance as a piece of French engineering.

Room Addition

The mansard rooftop provides two times as much space for lofts than hip or peak roofs, primarily because of its layout and outline. If a need to enlarge the main room, the loft region can fit easily. As well as enhancing the room’s appearance, dormer windows along the base slope will bring light into the structure.


It is much easier to add to and grow a mansard room than other types of rooms because of its construction. It is easier to add additional floors from here on out because of the upward slant of the base. Your mansard roof may be the best option if you plan to expand your home in the future.


Below are some of the cons of mansard loft conversion:

Permits are hard to obtain:

Depending on your area, different requirements may make it difficult for you to qualify for a grant. Before engaging in this interaction, you must understand the applicable neighborhood regulations.

Construction costs:

Mansards have high establishment costs because of their complexity. The cost of a single mansard roof could even be replaced with multiple peaks or hip roofs.


A mansard loft conversion Poole may not be the best choice if you live in an area subject to heavy precipitation or snow. It might even lead to a breakdown of the rooftop if water accumulates on the compliment upper slope due to the waste arrangement not being sufficient to withstand extreme weather patterns.

Bottom Line

There are many reasons why mansard loft conversions are the most beneficial. An aesthetically pleasing and attractive exterior combined with more space than any other style of loft conversion is the ultimate package. For many, these benefits are worth the cost and time, although they come at an increased price. In most cases, we will only ever need one loft conversion in our lives, so investing in the best might be a good idea.

Powerpillars can assist you if you aren’t sure what kind of loft conversion to get or whether a mansard loft conversion is proper for you.

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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