Basement conversion is the ideal way to extend your living space in London. From designer bathrooms and kitchens to wireless media rooms, flood-lit swimming pools and walk-in wine cellars, a basement development opens up a world of possibility.

Your home is reflection of who you are. Our bespoke Design & Build home renovation service offers truly client centred service. We build your dream home by gathering information about your aspirations, requirements and desired interaction with your newly renovated home.


Looking for a Loft Conversion Specialist? Loft Conversions in London

Loft Conversions

We carry out loft conversions and dormer loft conversions and are happy to offer advice and guidance at no obligation. When you decide to use Design & Build London our goal is to offer quality loft conversions in London, from concept through to completion, for the wide spectrum of client needs and tastes.

Experts in our Field

Our combined experience of 25 years ensures our loft conversion tradesmen are experts in their respective fields, so you can be assured your London loft conversion will be carried out to the highest standards. From an unused space we can design and build a study, office, hideaway retreat or bedroom with en-suite!

From Design Through to Build

When you chose Design & Build London we offer loft conversions for London from design through to build and finishes – this includes planning, building regulations, structure, stairs, Velux widows, dormer windows, insulation, plastering, heating, plumbing, bathroom fitting, electrical work and woodwork, lighting design and interior design! . However, if you would prefer to do (or manage) some of the elements yourself then we can tailor a package to suit your needs and are happy to start from any point of the project.

Types of Loft Conversions for London

  1. Dormer Conversions – London
  2. Mansard Conversions – London
  3. Velux Conversions – London
  4. Loft Conversion with Pod Room – London

Dormer Loft Conversion

L shaped Mansard Loft Conversion

Hip to Gable Loft Conversion

Velux / Skylights


The types of loft conversion design you can consider are Dormer, Mansard, Hip to Gable and Velux. The existing layout of the roof, and certain restrictions that apply, will determine the kind of loft conversion that the local authority will permit. DBL can advise you on this issue when we make our free, no obligation visit. Many clients ask “can we still live in our house during works?” Our answer is simple: Yes! This is because 80% of the materials will be brought in via the roof.

1. Dormer Loft Conversions – London

A dormer is an extension to the existing roof, creating additional floor space and headroom within the loft conversion. The dormer extension would project vertically from a sloping roof, internally a dormer has vertical walls and a horizontal ceiling.
If a loft has limited space or headroom a dormer will provide additional space that can make a conversion feasible.
Creating a gable front and a hipped roof dormer will make it look more attractive, however these types of dormers do not offer as much internal space, a gable front and hipped roof dormer will cost more to build due to the complexity of the build
Additionally, a dormer loft conversion can be constructed without requiring planning permission, depending on the specifications.

2. L-Shaped Mansard Conversions London
Named after the French Architect Francois Mansard from the 17th Century. A mansard loft conversion is located at the rear of the property. Typically, a mansard has a flat roof with the back wall sloping in at 72 degrees and has the advantage of maximising the full space within the loft. Planning permission would be needed due to the change in roof shape and structure.
While this type of roof desirable to maximise space in your loft conversion it does have a downside – as it involves replacing the entire roof the construction costs will be high.

3. Velux Conversions London
Velux loft conversions, also known as roof light conversions are easy to install and normally only require one of the existing rafters to be trimmed out per window. This type of conversion is very cost effective
As the loft is not extended beyond the original roof line and the structure left unaltered planning permission is not normally required.
A Velux type loft conversion works very well for lofts if there is already a good amount of headroom or if there are constraints on planning. If headroom is going to be limited then it may be better to consider a dormer or mansard conversion may be a better option.

4. Loft Conversion with Pod Room – London
A loft conversion pod room is built out usually over half of the back addition giving approximately 3m for a room. This is usually popular with clients who have already had a conversion and require more room. Pod rooms are the newest option for property owners in London, the space is perfect for a spare bedroom, office, luxury bathroom, playroom or nursery.

5. Loft Conversion with Roof Terrace – London
A demand for roof terraces have increased in London due to planning regulations being more relaxed, however roof terraces always require planning permission and are depending on the local authority. Why not create an open space outside? a place to enjoy the weather and entertain some friends.

Health and Safety at every stage

Health & Safety is of the utmost importance on every site on which we work. This is something that concerns all of our staff members, but also everyone else in the vicinity of the works, including you, your neighbours and even passers-by. Due to the nature of our work, there is always the risk of injury, or even death, as ladders, tools and various materials can be hazardous. That is why our staff are expertly trained and will always diligently adhere to all necessary Health & Safety procedures and issues.

Insurance and Guarantees

With numerous of basement conversion projects completed in London to date, DBL has an outstanding reputation for being conversion specialists, dedicated to creating state of the art spaces, with immaculate attention to detail.

Public Liability: £5,000,000
Employer’s Liability: £10,000,000
Contractors, All Risks: £6,000,000 Contract Limit / Subject to Survey

Truly Personal Services, From Start to Finish

We can deliver Design & Build projects in London and surrounding areas, projects including loft conversions and kitchen extension. We pride ourselves that our attention to detail is paramount to us. With meticulous precision to ensure that the proposed design satisfies the demanding needs of your style and aspirations. 

No matter what we do, we strive to preserve the privacy and security of your home. We complete our job with minimal disruption and ensure to install all needed safety measures to make the process exceptionally stress free.

No Hidden Cost, No Unexpected Expenses

The committed team at Design & Build London always completes the job within the pre-scheduled deadline and minimises the unexpected expenses associated with the construction process. Prior to the job, we accurately evaluate the exact requirements of the client, inspect the site appropriately, and prepare an all-inclusive, detailed quote that helps to cut down unanticipated expenses.

Flexibility and Prompt Customer Service

We provide you with an added bonus of a flexible site evaluation and prompt customer service at all times. We endeavour to take the time to listen to your needs and suggest the most viable solution that meets the highest possible standards.

Satisfaction Guaranteed

Our builders are extensively experienced and that’s why we are able to understand the complexities and potential issues that could occur as part of any full house renovation, loft conversion or kitchen extension project. Considering this challenge, we give our customers the convenience to enjoy a 10 year work guarantee on structural projects. Moreover, we provide adequate insurance coverage of up to £5 million. 

We cover all clients based in the London boroughs of Kensington & ChelseaHammersmith & TolworthWestminsterCamdenSouthwark, LambethWandsworth, MertonBarnes, Kingston upon Thames and Richmond.

  • cinema room
  • kids playroom
  • games room
  • gym
  • sauna
  • swimming pool
  • spa, massage room
  • sanctuary
  • nanny, granny and teenage flats
  • bowling alley
  • recording studio
  • luxury car park

Who we are

Design & Build London offer bespoke Design and Build basement conversion services tailor-made to your personal aspirations, requirements and habitual patterns. 

As a team, we have over 20 years of combined experience in modelling, designing and building beautiful homes across London.

Our team consists of:

• Project managers

• Pre-contract & contract managers

• Design consultants

• Quantity Surveyors

• Structural Engineers and professional Builders.

The result is a seamless service which allows us to provide a full Design and Build service under one roof.

We are one of the very few firms who choose not to ask for deposits or upfront payments.

Design & Build Basements

Our service is fully comprehensive, covering everything from your initial design ideas briefing, right through to the completion of your project:

We can take care of:

• Architectural Drawings

• Planning applications

• Building Control

• Project cost estimation

• Detailed architectural CAD / 3D designs

We are happy to work on projects across London from as little as £50,000 and are able to provide a full service for jobs right up to £3m+.

We ensure that we can take care of all aspects in regards to your projects, including: Basement Conversion, House Extensions, Loft Conversion


We work with RIBA Chartered Architects, and Architectural designers who are able to create and take care all drawings and plans on your behalf, and our high calibre builders who will turn your ideas into a reality, are full-time employed by our firm. This in result will ensure that all building work will be done in-house, which speeds up the whole sequential process.

Industry proven method to achieve minimising the delays between building stages of a project; in fact, through close nit teamwork, some tasks can be overlapped. No need to wait for next stage sign-0ff in order to allow the next task to begin can result in longer delivery of project. This advantage is most keenly felt in the transition between the planning and building phases; using a traditional approach, following the approval of plans, there is often a delay of several days, or maybe weeks, during which quotations are requested and received from building contractors.

We estimate that this reduces the time taken by some projects by up to 40%. Also, having to deal with a single company throughout the whole process is far easier for you, especially if an issue might arise, in which case responsibility cannot be shifted from one party to another.


Once armed with local authority policy, the necessary survey results and an outline budget estimate, you will need to design your basement space plan which will include:

  • How big and what shape it will be
  • How you propose to connect your new basement to your existing house
  • What’s the best space plan and room lay-out
  • A high level interior design plan and furniture lay- out so that you know the architectural design is in perfect harmony with the interior plan
  • Where to put services i.e. drains, electric runs, ventilation, etc.
  • Access and exit points including compliance with building regulations
  • Roof lights and light wells to provide lots of natural light and ensure a high quality living space

Our Featured Renovation Projects

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Structural design and calculations:

A structural engineer now needs to be appointed to decide and detail the best way to design, support and build your basement shell and core. The ‘shell and core’ is fundamentally the reinforced concrete structure in the ground. The engineer’s design will factor in all survey information available as well as your project timescales and budget constraints. The resulting piece of work is a series of drawings and calculations which identify the construction sequencing, materials, steelwork, under-pinning and/or piling details, party wall detailing and CDM (Construction Design & Management) requirements. The structural design is required before the Party Wall Agreement process starts as any appointed surveyor will want to review these as part of your Award.


Learn More…

Contact Us
Feel free to talk to us, at any time, about your ideas. You can contact us using the online form provided, or, if you wish, we can discuss your requirements during a site visit.

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By mastering best practices and applying them on every commercial and residential building project regardless of the budget or size, we can ensure lasting quality. We believe luxury home is about having standards and not cutting corners.

Our uncompromising aim is to deliver the highest quality refurbishment projects on brief, on time and within budget. We treat every job as a luxury project, with the same approach and same team of experienced, trained specialists working across our sites. Learn more about our Company.


There is no limit to the type of building project that we can undertake. We can renovate any part of your home, from converting your loft, to excavating your basement. We can also take on any scale of work, whether it be a complete new-build, the addition of an extension, or the renovation, remodelling or refreshing of an existing space.


One of the joys of working with our team of designers is the opportunity for you to witness the way in which we at Design & Build London painstakingly realise your design vision. We continually help you to visualise how your project is developing, using computer-generated images, ‘mood boards’ and drawings. We can even show you accurate representations of how your furniture and lighting configurations will look. Needless to say, with our vast experience in the trade, we are able to design your living space in a variety of styles.


The process begins with us helping you to visualise how your renovated home will look, and to imagine how you will live in it. From this initial conversation, we will develop a design brief in the form of a three-dimensional representation of your new living space. This will enable you to finalise your needs and aspirations.


Subsequent design work will produce a more formal specification, embodying the unique details of your specific requirements. You can be sure that this detailed spec will be highly personalised to your needs and aspirations.


The final stage of the process is to finalise decisions as to the materials and finishes that will be used. We can help you to select the look and the textures that blend perfectly with your living space, and we can also advise you on solutions that meet sustainability objectives. We believe that the look of your living space should complement and enhance your lifestyle, and not dominate it.




Having the full range of skills and trades in-house enables us to fully control the entire build process, from the initial discussion of your requirements, to the final sign-off of the completed build. Rather like a Michelin-starred restaurant that likes to inspect every ingredient on its menu before it reaches the customer’s table, we jealously guard the quality of every detail of the service that we provide for our customers.

The desire to bring all of our disciplines in-house was born out of a vision to help our clients create truly exceptional homes. Not unlike the finest restaurants in the world that control every element of preparation from field to fork. Sourcing the most delectable and rare ingredients and combining this with hugely dedicated and experienced teams, to produce unforgettable gastronomic experiences. These are precisely the service levels that our clients receive and have come to expect whilst working with us.

Net Promoter


A standardised measurement of customer loyalty and the likelihood of a recommendation.

Client Retention


of clients continue to use us for future construction or architecture projects.



of our work comes from word-of mouth recommendations alone.

Net Promoter


A standardised measurement of customer loyalty and the likelihood of a recommendation.

Client Retention


of clients continue to use us for future construction or architecture projects.



of our work comes from word-of mouth recommendations alone.

Get in touch
We are always happy to chat. Contact us to arrange an initial meeting or you can use our project enquiry form.

Full Name: (required)
Address and Postcode:
Your Email (required)
Telephone: (required)

Brief Description of your project

Interior Design

Helping you create your dream home

  • Interior Design service for your home
  • Advising on styles, materials, feasibility
  • Producing detailed plans and 3D images
  • Fittings, furnishings, colours and lighting
  • Maximising best features of your property
Contact Us

Project Management

Making property renovation happen

  • Project Concept, Design and Planning
  • Preparing schedules of work, finishes & timelines
  • Free quotes
  • Design and Build team under one roof
  • Problem-solving and troubleshooting
Contact Us

Home Staging

Maximising your property’s value

  •  Increase your property market price
  • Maximise the best features of the house
  • Suggest cost effective, maximum impact solutions
  • Arrange quick execution of the project
  • Property investment
Contact Us

Design & Build Ltd
55 Putney Hill,
SW19 6RZ