Dormer Loft Conversion


  • Specialist Loft Conversion Builders in London
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dormer loft conversion


A dormer loft conversion is a transformative home improvement solution that opens up your attic space for a myriad of uses. Essentially, a dormer is a structural extension which projects vertically from the plane of a sloping roof. By constructing a dormer onto your existing roof, you can significantly increase the usable floor space and headroom in your loft. This makes dormer conversions an ideal choice for homeowners looking to add value and functionality to their properties. If you’re based in the capital, you’ll find that dormer loft conversions are an especially popular option due to the premium on living space.


Choosing a dormer loft conversion offers several advantages. Firstly, the added height and space make your loft a versatile area, usable for everything from an extra bedroom to a home office or playroom. Second, dormers typically include windows, which means more natural light filtering into your new space, making it feel more open and inviting. Lastly, compared to other types of loft conversions, a dormer is often more cost-effective, especially when you consider the significant return on investment it can provide. Whether you’re new to the concept or already considering a loft transformation, this comprehensive guide will cover everything you need to know about dormer loft conversions.


Single Dormer

A single dormer loft conversion involves adding a ‘box’ structure to one side of your existing sloping roof. This is the simplest form of a dormer and is often the go-to choice for those looking to add a modest amount of extra space. A single dormer is ideal for smaller properties and can serve various purposes, such as creating room for an office or an additional bedroom.

Double Dormer

Double dormers are essentially two single dormers placed on opposite sides of the roof. This design utilises both slopes of the roof, providing a significant increase in floor space and natural light. Double dormers are particularly useful for larger properties or for those who wish to create multiple rooms in their loft space.

L-Shaped Dormer

An L-shaped dormer loft conversion is a more complex structure that essentially joins two dormer extensions at a right angle, forming an ‘L’ shape. This type of dormer is particularly well-suited for Victorian terrace houses or semi-detached properties in London, where the extra space can often accommodate two or even three new rooms.

Before deciding on the type of dormer that’s right for you, it’s crucial to consult professionals who can assess your property’s structural integrity. Here’s a guide on structural considerations that might help you understand this aspect better.

l shaped dormer loft conversion

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completed loft conversion with visible brick wall - Design and Planning


Navigating the maze of planning permissions can often seem daunting, especially if you’re new to home renovations. However, understanding the essentials can simplify the process and help you avoid unnecessary delays and costs.


When it comes to dormer loft conversions, the planning permission requirements can vary based on several factors such as the size of the project, its location, and the type of property you own. Generally, smaller dormer conversions might not require planning permission, falling under what’s known as “permitted development rights.” However, these rights are often subject to conditions, and it’s crucial to confirm this with your local planning authority.


You may not need planning permission for your dormer loft conversion if it meets certain conditions, such as being smaller than a specific size or located at the rear of the property rather than facing a public road. However, if your building is listed or located in a conservation area, planning permission is usually mandatory. It’s always advisable to consult a professional planner to clarify these details, especially given the intricacies of London’s planning regulations.

When considering planning permissions, also bear in mind the need for a Party Wall Agreement if your property shares a wall with a neighbour. Failure to secure this agreement can lead to legal complications down the line.

Before you start any construction, it’s also worth understanding the electrical and fire safety requirements, which could influence your project’s design and cost. For more information on these topics, you can refer to our comprehensive guides on Electrical Safety and Fire Safety.

dormer loft conversion london


Floor Joist - Clapham Construction


While planning permission focuses on the external appearance and impact of your dormer loft conversion, building regulations ensure that the construction work itself is of a high standard and safe. In London, adhering to building regulations is crucial and covers aspects like structural integrity, fire safety, and energy efficiency. Meeting these standards is not just a legal requirement but also ensures that your conversion is a safe and long-lasting addition to your home.


Professional planning is essential for the success of your dormer loft conversion project, particularly in London where space is often at a premium. A seasoned planner can help you make the most of your space, ensure that you meet all building regulations, and even find ways to save on costs. Their expertise can be invaluable in guiding you through the maze of permitted developments and planning permissions.


One of the first things to consider is the available ceiling height in your existing loft. Traditional roofs usually have a height of 2.2-2.4 meters, while modern trussed roofs might offer 2.4-2.6 meters at their highest point. If the height is less than these standards, you might need to adjust the floor levels below or opt for a different type of conversion. Keep in mind that altering the floor levels could have implications for your project’s overall cost and timeline.


Once the practical considerations are in place, you can focus on the exciting part: what to do with your newly acquired space. Here are some room ideas that are perfect for dormer loft conversions:



The materials you choose for your dormer loft conversion can have a significant impact on both its appearance and its environmental footprint. We are committed to using high-quality, sustainable materials that not only stand the test of time but also contribute to a greener planet. From energy-efficient insulation to sustainably sourced timber, our choices aim to reduce the environmental impact of your conversion project.


Dormer loft conversion - Bathroom


Undertaking a dormer loft conversion in London is a significant commitment that requires both financial planning and a clear understanding of the project’s duration. Below, we break down the key factors you’ll need to consider.


While dormer conversions are generally viewed as a budget-friendly way to expand your living space, the actual costs can vary. Typical starting prices hover around £35,000, but several elements can influence the final amount. These can include the complexity of the design, whether or not planning permission is needed, and the finishes you choose for the interior.


Dormer conversions are known for their relative speed of construction, often falling into the ‘minimal disruption’ bracket. This means you could be enjoying your new space in just weeks. However, the timeline can extend if you encounter challenges such as the need for planning permission or if unforeseen issues arise, such as structural complications.

By understanding these elements in advance, you can manage your expectations and plan more effectively, making your dormer loft conversion a smoother process overall.


When it comes to dormer loft conversions in London, not all construction services are created equal. Here’s why choosing us for your project is a decision you won’t regret.

Our Expertise

With years of experience in the construction industry, we’ve successfully completed numerous dormer loft conversions across a wide range of property types. Our team is well-versed in navigating London’s complex planning regulations and delivering projects that not only meet but often exceed our clients’ expectations.

Book a Free Consultation

The first step in any successful loft conversion is a detailed consultation. We offer a free initial consultation to discuss your needs, assess your property, and provide you with a tailored solution that fits both your vision and budget. To book yours, simply give us a call or fill out our online form.

Contact Details

For more information or to get started on your dormer loft conversion project, you can reach us at:

Phone: 0203 950 7957
Email: [email protected]

home insurance for loft conversions

Have your say…


Nicholas Carpenter
Nicholas Carpenter
Clapham Construction have done a great job on our loft conversion and we are very pleased with how smoothly the project went, and the brilliant loft space that we now have. Paul - thank you especially for guiding us through all the stages before and during the build. Their workmen were hard working from start to finish, efficient, and obviously very skilled. They were also polite, helpful and really tidy. We had great communication by email with their office, and with Paul in person and on the WhatsApp group - thank you. Our family in USA are now looking forward to staying with us in comfort this summer and beyond!
Bianca Hamilton
Bianca Hamilton
Paul, Dangis and the team are simply top notch. They did such a high-quality job on a tight timeframe and communicated so well throughout. They were a pleasure to work with, handled all elements of the build from start to finish and kept disruption as minimal as they could. Couldn’t recommend them more highly if I tried.
Mindy Lee
Mindy Lee
Thank you Clapham Construction! Your team were friendly, efficient, and highly motivated. The project ran to schedule with effective overlapping of tasks to allow for minimum disruption. Paul kept us actively involved at each stage of the process, so we always knew what was happening when, which was really reassuring. If we ever had a question, he would talk it through with us in person and offer advice without any pressure or expectation. The work is completed to an excellent standard. All the construction workers where kind, considerate, friendly, polite and kept our house as clean and tidy as possible. This took so much of the stress out of living on site during the works with a young son. Even the neighbours commented on how polite and considerate the builders had been. We would highly recommend this team for anyone thinking of undertaking a loft conversion in the future.
Shayan Bokhari
Shayan Bokhari
Paul, Dangis and their team were excellent given we had some obstacles with the council on design, they accommodated what we required. The work was very professional and communication was on point. We are very happy with our end result and any teething issues they resolved quickl. I would recommend the team to anyone. Thanks again for all your hard work.
Laila A
Laila A
Really lovely team - all professional, friendly and was great to have Dangis and Paul popping in regularly and being on the ball with the project. Happy with our new loft, all work done to an excellence standard, any follow up questions or issues dealt with quickly. Would highly recommend. Thank you very much.
Dani Carter
Dani Carter
Absolute professionals is the first thing that comes to mind when I think of Clapham Construction service. And there are two further things you need to know about them: they are brilliant at what they do and they are generous in spirit. Throughout our project Paul and Dangis answered our naive questions with warmth and care. They helped guide us at every turn, and almost certainly saved us money by making sure we considered all the options we had before making key decisions. But not just customer care, the building work is also top notch. The build itself was a well oiled process, coordinated with skill. I was initially worried about getting an anonymous loft company I'd never heard of in (after getting 8 different quotes from a variety of places including famous local ones) and being part of the 'box on the roof' brigade. Yet somehow, they have created build magic with some tweaks on 'a little bit of height' here, and 'a little configuration' there. We keep marvelling at the sturdiness and smoothness of the physical build even now, and the army of highly skilled teams they have were a pleasure to host in the house while we worked from home. And finally the most important bit - the money stuff- our Loft extension (including bathroom) was completed on time and more or less on budget. The additional costs were the unforseen - (yikes a victorian chimney needs dismantling!) and a few flourishes that we ourselves added to the mix - (can the door handles be gold?). Any additional build costs were communicated efficiently and immediately. Our experience of Clapham Construction is that they are patient, hugely knowledgable, and detail orientated with a wealth of incredible advice. Don't delay on getting them on your project!
Mikey Johns
Mikey Johns
We spoke to a few companies to quote our dormer loft conversion but were immediately impressed speaking to Dangis & Paul and went with Clapham CS. We’re really happy with the end result which has given us some much needed extra space. Progress was quick, these guys are very experienced and know exactly what they’re doing. They’ll talk you through your plans and give you honest advice at key stages when you need to make a decision, very patient with us too! Would definitely recommend, they’ve done numerous houses in our neighbouring streets too, end results always look great.
Maria Luisa McKendry
Maria Luisa McKendry
Highly recommend this company. As first time buyers and first time renovators we couldn't be happier with their service. Paul and Dangis are very professional and thorough, at no times does it feel like corners are cut. They are able to provide genuine advice and guidance while being accommodating ensuring a stress free process.
Stuart Williams
Stuart Williams
Clapham Construction completed our kitchen extension for us. We’re really pleased with the results, and it has changed the whole place. The price was agreed upfront and there were no hidden extras. Good communication throughout the whole process on WhatsApp and Dan showed great building experience. They had the whole team from build, kitchen fitting through to finishing the garden off available in house so made it a lot easier. Thanks guys.
Tom Forman
Tom Forman
We are delighted with our new loft conversion, Clapham Construction did a great job. They were highly professional, no hidden costs, and with friendly employees who treated the rest of the house with respect. We would not hesitate to recommend them.

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What is a dormer loft conversion?

A dormer loft conversion is a structural extension which projects vertically from the plane of a sloping roof. By building a dormer onto an existing roof, you can convert a cramped attic into a usable space filled with light.

How much does a dormer loft conversion cost?

The cost of a dormer loft conversion can vary greatly depending on the size of the project, the materials used, and the location of the property. On average, you can expect to pay between £40,000 and above.

Do I need planning permission for a dormer loft conversion?

In many cases, a dormer loft conversion falls under permitted development rights and does not require planning permission. However, this can depend on a number of factors including the size of the conversion and the location of the property. It’s always best to check with your local planning authority.

What types of dormer loft conversions are there?

There are several types of dormer loft conversions, including flat roof, gable fronted, hipped roof, and shed dormers. The type that’s best for you will depend on your property, your budget, and your personal preferences.

How long does it take to complete a dormer loft conversion?

The length of time it takes to complete a dormer loft conversion can vary depending on the complexity of the project. However, on average, you can expect the work to take between 4 to 6 weeks.

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