How much does a loft conversion cost in the UK?

Typical loft conversion costs in the UK start from around £25,000–£30,000 for a simple Velux conversion, £35,000–£50,000 for a dormer loft conversion and upwards of £55,000+ for larger or more complex projects. The final price depends on the size of your loft, structural work required, the level of finish, and whether you need an en-suite or additional plumbing and electrics. We provide a detailed fixed quotation after a free on-site survey so you know exactly what your loft conversion will cost before work begins.

How long does a loft conversion take from start to finish?

Most standard loft conversions take around 6–10 weeks on site once all designs and approvals are in place. A simple Velux loft conversion is usually completed at the faster end of this range, while larger dormer or mansard conversions may take slightly longer. We plan the schedule carefully, keep disruption to a minimum, and provide you with a clear start and completion date before work begins.

Will my loft conversion add value to my home?

A professionally designed and built loft conversion almost always adds significant value to a property, often increasing the market value by 15–25% depending on location and specification. Adding an extra bedroom and bathroom is particularly attractive to buyers and can be more cost-effective than moving home. During the design stage we help you plan a layout that maximises both usable space and potential resale value.

Can my loft be converted?

Most lofts can be converted, but we need to assess key factors such as available head height, roof structure, access for a new staircase, and the condition of the existing roof. As a guide, you usually need at least 2.2 metres of clear height at the highest point before any construction work. During our free initial survey, we check these details, explain what is possible in your property, and suggest the most suitable type of loft conversion for your home.

What types of loft conversion do you offer?

We design and build all main types of loft conversion, including Velux (rooflight) loft conversions, rear and L-shaped dormer conversions, hip-to-gable extensions, and full mansard loft conversions. We tailor each project to the style of your property and your requirements, whether you want an extra bedroom, a home office, a master suite with en-suite bathroom, or a multi-purpose living space.

Will a loft conversion cause a lot of disruption?

Our aim is to keep disruption to your day-to-day life as low as possible. Much of the early work is carried out from scaffolding and through the roof, which helps reduce mess inside the house. We protect floors and stairs, keep the site tidy, and schedule noisy work at reasonable times. A dedicated project manager will keep you updated throughout so you know exactly what is happening and when.

Is my loft conversion covered by a guarantee?

Yes. Our loft conversions are built to current Building Regulations and come with a structural warranty for the work we carry out. All materials and fixtures are sourced from trusted suppliers and are installed by experienced, fully insured tradespeople. We also arrange building control inspections and certification on completion, giving you written proof that your new loft has been built and signed off to the correct standard.

Do you handle design, structural calculations and Building Regulations?

We offer a complete design-and-build service for loft conversions. This includes initial concept design, detailed drawings, structural engineering calculations, and all Building Regulations submissions. We liaise with building control, arrange inspections and ensure every element of the conversion – from fire safety and insulation to stairs and electrics – complies with the latest regulations. This end-to-end approach keeps the process simple and stress-free for homeowners.

How do I get a quote for a loft conversion?

To get a quote, you can contact us via the enquiry form on our website, call our office or email your details and any existing plans. We will arrange a convenient time to visit your property, discuss your ideas, measure the space and advise on the best loft conversion options. After the survey, we provide a detailed, itemised quotation with clear costs and a proposed timescale, so you can make an informed decision before committing.

Loft Conversions in London & Surrey

Q: Do I need planning permission for a loft conversion?

Many loft conversions fall under Permitted Development rights and do not need full planning permission, provided the design meets certain limits on size, materials and overlooking. However, mansard and some hip-to-gable conversions, or projects in conservation areas and flats, may require a formal planning application. We assess your property, advise you on whether planning permission is required, and handle all drawings and applications with the local authority if needed.

Transform your unused attic into a bright new bedroom, office or living space with our fully managed loft conversion service.

Design & build loft specialists
Fixed-price quotes & clear timelines
Planning & Building Control handled for you
10-year structural guarantee

Request a Free Loft Survey View Recent Loft Projects

Get a Free Loft Conversion Quote

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Specialist Loft Conversions Across the South East

Best Builders delivers high quality, fully compliant loft conversions in London, Surrey and the surrounding areas. Whether you want an extra bedroom, a luxury master suite, a quiet home office or a playroom for the children, our loft conversion specialists will turn the unused space under your roof into a warm, comfortable and beautifully finished room that adds real value to your home.

From the first survey and architectural drawings through to structural work, electrics, plumbing, plastering and final decoration, we manage every stage in-house. You deal with one experienced project manager, one schedule and one transparent fixed price.

Why Homeowners Choose Our Loft Conversion Service

Design & build service: In-house designers, structural engineers and build teams ensure a seamless process.
Planning made simple: We advise whether your loft falls under Permitted Development or needs full planning permission, and handle applications on your behalf.
Building Regulations compliant: All structural work, fire safety measures, insulation and electrics are signed off by Building Control.
Fixed, detailed quotations: No vague estimates – we itemise the full scope so you know exactly what is included.
Respectful on-site teams: Clean, polite tradespeople who protect your home and minimise disruption.
10-year structural guarantee: Peace of mind that your new loft space is built to last.

Most projects can be completed in as little as 6–8 weeks once on site, with careful planning so you can continue living in your property while work takes place.

Areas We Cover

Our loft conversion teams work right across:

Central & South West London
South East & North London
Surrey & Middlesex
Parts of Berkshire & Kent

If you're unsure whether we cover your postcode, send an enquiry and we'll confirm within one working day.

Typical Loft Uses

Master bedroom with en-suite
Guest bedroom & shower room
Home office or studio
Playroom or teenage den
Hobby room or home gym
Walk-in wardrobe & storage

Types of Loft Conversion We Offer

Every property is different, so we design your loft conversion around the shape of your roof, your budget and how you plan to use the space. Our team will suggest the best solution during your free survey, but these are the most popular loft styles we build across the UK.

Velux / Rooflight Loft Conversions

A Velux loft conversion uses the existing roof shape without major structural alterations. We add high performance roof windows between the rafters, insulate the space and create a full, liveable room.

Usually the most cost-effective option
Minimal external changes to your property
Often possible under Permitted Development
Ideal for home offices, nurseries or hobby rooms

Dormer Loft Conversions

Dormer loft conversions extend vertically from the existing roof, creating extra head height and usable floor area. This is the most common type of loft conversion in terraced and semi-detached houses.

Large, flexible rooms with good ceiling height
Perfect for master suites with en-suite bathrooms
Can run full width across the rear of the property
Flat roof and pitched roof dormers available

Hip to Gable Loft Conversions

On end-of-terrace and many semi-detached houses, the existing sloping side roof (the hip) can be built up vertically to form a gable wall, dramatically increasing the internal space.

Adds substantial headroom and floor area
Often combined with a rear dormer for maximum space
Great solution for hipped roofs that feel too small
Maintains a balanced look from the street

L-Shaped & Mansard Loft Conversions

For period properties and larger homes, L-shaped or mansard loft conversions can create impressive, almost apartment-style spaces with multiple rooms and generous natural light.

Maximises the footprint on Victorian & Edwardian homes
Ideal for adding two bedrooms and a bathroom
Can significantly increase property value
Designed to complement the original architecture

Our Step-by-Step Loft Conversion Process

We aim to make your loft conversion straightforward and stress-free. From concept to completion, our tried-and-tested process keeps everything organised and on schedule.

Initial Consultation

We visit your property, measure your existing loft, discuss your ideas and check what is structurally and financially realistic.

Design & Quotation

Our designers prepare proposed layouts and, if required, planning drawings. You receive a fixed-price, fully itemised quotation.

Permissions & Approvals

We handle planning applications, Party Wall matters (if needed) and Building Control approvals, keeping you updated at each stage.

Construction & Handover

Our build team completes the structure, insulation, electrics, plumbing and finishing touches before a final snag check and sign-off.

Throughout the project you will have a dedicated project manager who is your single point of contact, making it easy to get quick answers and regular updates.

Benefits of a Loft Conversion

A professionally designed loft conversion is one of the most cost-effective ways to extend your home in the UK.

Increase Property Value

Adding an extra bedroom and bathroom can significantly increase your home's market value, often more than covering the cost of the works.

Avoid Moving Costs

Stay in the location you love while gaining the extra space you need, without the expense and hassle of stamp duty, legal fees and removals.

Better Energy Performance

Modern insulation and windows improve the thermal performance of your roof space, making your whole home warmer and more efficient.

Flexible New Living Space

From quiet home offices to bright playrooms, guest suites or teenager bedrooms, your loft can adapt as your family’s needs change.

Make Use of Wasted Space

Most lofts are used only for basic storage. Turning the area into a proper room makes the most of your existing footprint.

Designed Around You

We tailor every aspect – from roof lights and dormers to stair placement and built-in storage – so the new room works perfectly for your lifestyle.

Recent Loft Conversion Projects

Here are just a few examples of loft conversions we have completed for homeowners in London and the South East.

Rear Dormer, Wimbledon

Spacious master bedroom with en-suite shower room and built-in wardrobes.

Velux Loft, Clapham

Bright home office and guest room using large roof windows and slimline radiators.

L-Shaped Loft, Kingston

Two children’s bedrooms and a shared bathroom created above a Victorian terrace.

To see more before-and-after photos and technical details of our loft conversions, please contact our team and we’ll share relevant case studies for your property type.

Loft Conversion FAQs

Below are answers to some of the most common questions UK homeowners ask us about loft conversions.

Do I need planning permission for a loft conversion?

Many loft conversions in England and Wales fall under Permitted Development rights, which means full planning permission is not required if certain conditions are met. However, you will always need Building Regulations approval. Our team will check your property, advise on the rules that apply in your area and prepare all necessary documentation.

How long does a loft conversion take?

Timescales vary depending on the size and complexity of the project. As a guide, a straightforward Velux conversion may take 4–6 weeks on site, while a larger dormer or hip-to-gable loft is typically 6–8 weeks. We outline a clear programme before work starts and keep you updated throughout.

Will a loft conversion add value to my home?

In many parts of London and the South East, adding an extra bedroom and bathroom can significantly increase your property’s value. Estate agents often see well designed loft conversions delivering an excellent return on investment. During your survey we can discuss how different layouts may impact potential resale value.

Can every loft be converted?

Most lofts can be converted, but a few factors need to be checked: available head height, roof structure, access for a new staircase and any planning restrictions in your area. Our survey will identify what is possible and, if needed, we can propose structural changes to make the loft workable.

Will there be much disruption?

We plan loft conversions so that the majority of structural work is carried out from scaffolding and through the roof, limiting disruption inside the house. We protect floors and belongings, keep work areas tidy and schedule noisy works considerately. Most clients remain living in their homes throughout the build.

How much does a loft conversion cost?

Costs depend on the type of loft conversion, size, specification and whether you are adding bathrooms or bespoke joinery. After your free survey we provide a detailed, fixed-price quotation with no hidden extras. This allows you to compare options and choose the right solution for your budget.

Ready to Transform Your Loft?

Book a free, no-obligation loft conversion survey and discover what’s possible in your home. We’ll provide clear advice, creative ideas and a detailed quote.

Request Your Free Loft Survey

Updated on 27 Dec 2025