What is a Mansard Loft Conversion?

This type of conversion changes the sloping side of your roof to an almost vertical side – one of at least 72 degrees. The roof is flat and windows are typically housed within small dormers.

Is Planning Permission Required for Mansard Loft Conversions?

Planning permission is almost always required for this type of extension. These conversions create maximum living space within your roof by effectively creating another storey to your property. As this results in changes to the roof shape and structure, it is highly likely that planning permission will be needed from your local authority.

How Much do Mansard Loft Conversions Cost?

This type of loft extension is often more expensive than other types, such as a dormer or hip-to-gable conversion.

What Types of Houses are Best for Mansard Conversions?

Mansard roofs are particularly common in London and other urban areas and can often be seen across whole rows of older terraced properties.

Flat Roof Extensions: A Complete Guide

Flat roof extensions are a popular and cost-effective way to add valuable living space to your home. Whether you’re looking to create a larger kitchen, a family dining area, or a bright and airy home office, a flat roof extension can be a versatile and stylish solution.

At Abbey Partnership, we have over 20 years of experience in designing and building high-quality home extensions. Our team of experts will work with you to create a bespoke flat roof extension that meets your needs and complements your home’s existing character.

What Are Flat Roof Extensions?

A kitchen extension ( exterior view of a rear extension).

A flat roof extension is a single-storey property addition, with a roof that has a very slight pitch – typically between 1 and 10 degrees. This minimal slope allows for effective rainwater drainage while maintaining a modern, streamlined aesthetic.

Flat roof extensions can be built onto the rear or side of a property and are a popular choice for homeowners looking to maximise their living space without the expense of a pitched roof. They are particularly well-suited to modern and contemporary properties, but can also be designed to complement more traditional homes.

Advantages of Flat Roof Extensions

There are many benefits to choosing an extension with a flat roof for your home:

Cost-effective

Flat roof extensions are generally more affordable to build than their pitched roof counterparts, as they require fewer materials and are quicker to construct.

Versatile design

The simple, clean lines of a flat roof extension offer great design flexibility. They can be easily incorporated into a wide range of property styles and can be customised with features such as rooflights, lanterns, and green roofs.

Maximise space

The internal ceiling of a flat roof extension follows the line of the roof, creating a consistent height across the room and maximising the available headroom.

Speed of construction

Due to their simpler design, flat roof extensions can often be built more quickly than pitched roof extensions, minimising disruption to your home life.

Potential for a roof terrace

A flat roof can be designed to be used as a roof terrace or balcony, providing valuable outdoor living space, particularly in urban areas.

How Much Does a Flat Roof Extension Cost?

The cost of a flat roof extension can vary depending on a number of factors, including the size and complexity of the design, the materials used, and your location. On average, you can expect to pay between £1,500 and £2,500 per square metre for a flat roof extension.

For a more accurate quote, please contact us to arrange a free, no-obligation consultation with one of our design experts. We will discuss your requirements in detail and provide you with a comprehensive breakdown of the process and all costs involved.

Flat Roof Extensions: Permitted Development and Planning Permission

Many flat roof extensions can be built under Permitted Development rights, which means you won’t need to apply for full planning permission. However, there are certain criteria that your extension must meet in order to qualify.

Permitted Development Rights

Under Permitted Development, a single-storey rear extension must not:

Extend beyond the rear wall of the original house by more than 4 metres for a detached house, or 3 metres for any other type of house.
Be more than 4 metres in height.
Be within 2 metres of a boundary if it is more than 3 metres in height.
Cover more than 50% of the land around the original house.

When Planning Permission is Required

You will need to apply for planning permission if your proposed extension does not meet the criteria for Permitted Development, or if your property is in a conservation area, a National Park, or an Area of Outstanding Natural Beauty.

At Abbey Partnership, we have extensive experience in navigating the planning process. We can advise you on whether your project is likely to require planning permission and can prepare and submit the application on your behalf.

Why Choose Abbey Partnership for Your Flat Roof Extension?

Modern loft conversion kitchen with white cabinets, wood floors, and natural light from window.

When you choose Abbey Partnership for your flat roof extension, you can be confident that you are working with a team of experienced and dedicated professionals. We pride ourselves on our commitment to quality, customer service, and transparency.

Over 20 years of experience: We have a proven track record of delivering high-quality home extensions on time and on budget.
Bespoke design service: Our in-house design team will work with you to create a flat roof extension that is tailored to your specific needs and style preferences.
Transparent pricing: We provide a detailed, fixed-price quote for every project, so you can be sure there will be no hidden costs.
10-year guarantee: All of our work is covered by a 10-year independent guarantee, giving you complete peace of mind.
Exceptional customer service: We are committed to providing our customers with a seamless and stress-free experience from start to finish.

Your Dream Extension, Realised

A flat roof extension is a fantastic way to enhance your home and create the extra space you and your family need. With their versatility, affordability, and modern appeal, it’s no wonder they are such a popular choice for homeowners across the UK.

If you’re ready to take the next step towards your dream home extension, contact Abbey Partnership today. We’ll be with you every step of the way, from the initial design concept to the final finishing touches.

Flat Roof Extensions: FAQs

Is a flat roof extension cheaper?

Yes – in most cases, a flat roof extension is cheaper than a pitched roof extension. This is because they require fewer materials and are less complex to build, which reduces both material and labour costs.

Is a flat roof extension a good idea?

A flat roof extension can be an excellent idea. They are a cost-effective way to add space and value to your home. With modern materials and construction techniques, they are also durable, long-lasting, and can be very energy efficient.

Do flat roof extensions leak?

Modern flat roofs are highly resistant to leaks. Advances in materials such as EPDM rubber, GRP fibreglass, and single-ply membranes mean that a well-installed flat roof can be just as watertight as a pitched roof.

How long do flat roof extensions last?

The lifespan of a flat roof depends on the materials used. A traditional felt roof can last for around 10-15 years, while modern materials like EPDM and GRP can last for 50 years or more with minimal maintenance.

Can I walk on my flat roof extension?

It is not advisable to walk on a standard flat roof extension unless it has been specifically designed for that purpose. If you would like to use your flat roof as a balcony or terrace, it will need to be strengthened to support the additional weight.

Do you need planning for a flat roof extension?

Many flat roof extensions fall under Permitted Development rights and do not require planning permission. However, there are size and height restrictions, so it’s always best to check with your local authority or a building professional.

It’s also worth noting that Permitted Development rules vary slightly depending on the location of your extension. For instance, a flat roof rear extension can typically extend further from the original property than a flat roof side extension. A side extension also cannot be more than half the width of the original house.

What is the best material for a flat roof?

The best material for a flat roof depends on your budget and requirements. EPDM rubber is a popular choice as it is durable, long-lasting, and relatively affordable. GRP fibreglass is another excellent option, offering a seamless and highly waterproof finish.

Can I put a skylight in a flat roof extension?

Yes, skylights and roof lanterns are a fantastic addition to a flat roof extension. They can flood the space with natural light, making it feel bright, airy, and more spacious.

How is a flat roof drained?

Flat roofs have a slight pitch to allow water to run off into a gutter or internal drainage system. The pitch is usually created by using tapered insulation boards or by building a slight slope into the roof structure.

Are flat roof extensions energy efficient?

Yes, flat roof extensions can be very energy efficient. Modern building regulations require them to be well-insulated, which helps to keep your home warm in the winter and cool in the summer, reducing your energy bills.