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.

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.

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.

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Q: 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.

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Loft Conversion Types & Costs

How Much Does a Loft Conversion Cost in the UK?

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Dormer Loft Conversion

Rear Dormer with En-Suite

£30,000 – £81,000

The most popular type in the UK. Creates a full-height room with a vertical rear wall and flat roof. Usually includes a bathroom and Velux windows to the front.

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Hip-to-Gable Conversion

Hip-to-Gable with Dormer

£33,000 – £93,000

Ideal for end-of-terrace and detached homes with a hipped roof. Extends the ridge line to create maximum usable floor space. Often paired with a rear dormer.

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Mansard Conversion

Mansard Loft Conversion

£38,000 – £113,000

The most spacious conversion type — a near-vertical rear wall with a shallow-pitched roof. Common in London and city terraces. Typically requires planning permission.

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Your Project

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Costs vary by conversion type, roof structure, specification and region. Compare 3 quotes from vetted local specialists.

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Regional pricing note: Loft conversion costs are higher in London and the South East. Mansard conversions in inner London can exceed national averages by 35–45%. Use our local cost guide for town-specific ranges.

Loft Conversions UK

Convert Your Loft With a Vetted Specialist

A loft conversion is one of the best-value home improvements you can make in the UK. It adds a full habitable room — typically a bedroom with en-suite — without taking any garden space, and consistently delivers strong returns in almost every UK property market.

Getting it right requires a specialist who understands structural engineering, roof types, permitted development rules, party wall requirements and building regulations. BestBuilders connects you with FMB and CIOB-qualified loft conversion specialists who have the experience to handle your specific property type and roof configuration.

Every specialist in our network is verified for insurance, qualifications and genuine customer reviews before they receive a single lead from us.

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How It Works

Tell us your conversion type and postcode

60 seconds. Not sure of the type? Select "Not sure yet" — specialists will advise.

We match you with local loft specialists

Up to 3 vetted specialists in your area, within 24 hours.

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No obligation to proceed with anyone.

Every Specialist We List Is:

✓ Minimum £2m public liability insurance — verified before listing

✓ Holds relevant trade qualifications (FMB, CIOB)

✓ Minimum of 5 verified customer reviews before joining

✓ Actively monitored — removed for sustained negative feedback

Choosing the Right Type

Which Loft Conversion Suits Your Property?

The right conversion type depends on your roof shape, property type and planning context. Here's a guide to help you narrow it down.

🏠

Terraced & semi-detached houses

A rear dormer is the most common choice — it maximises usable floor area without affecting the front roofline. Victorian and Edwardian terraces with steep pitched roofs are ideal candidates. A Velux conversion is cheaper but suits taller roofs with sufficient existing headroom.

Best option: Rear dormer

🏡

End-of-terrace & detached homes

If your home has a hipped roof (where the roof slopes on all four sides rather than having a gable end), a hip-to-gable conversion is the most effective way to maximise space. It's usually combined with a rear dormer for the best result. Most hip-to-gable conversions fall under Permitted Development.

Best option: Hip-to-gable + dormer

🏙

London terraces & city properties

A mansard conversion creates the most usable space — the rear roof slope is replaced with a near-vertical wall, transforming the entire loft into a full-height room. Common in London mid-terraces and conservation area properties. Typically requires planning permission but delivers the biggest floor area gain.

Best option: Mansard conversion

Not sure which type suits your home?

Select "Not sure yet" in the quote form and describe your property type. The specialists we match you with will assess your roof during the site visit and recommend the most suitable conversion — without any obligation to proceed.

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What's Involved

What's Typically Included in a Loft Conversion

🏗 Structural work

✓ Steel beams (RSJs) for floor support

✓ New roof structure for dormer or mansard

✓ Floor joists to Building Regs standard

✓ Structural calculations and sign-off

🚿 Plumbing & electrics

✓ En-suite bathroom plumbing first fix

✓ Electrical first and second fix

✓ Lighting design and sockets

✓ Heating extension or dedicated source

🪟 Finishing

✓ Staircase design and installation

✓ Roof windows or dormer windows

✓ Insulation to Part L standard

✓ Plastering, flooring and decoration

Customer Reviews

What Homeowners Say About Our Loft Specialists

★★★★★ 4.8 / 5

★★★★★

Three quotes in 24 hours for our dormer loft conversion. All specialists had clearly done dozens of similar projects. The one we chose was brilliant — handled planning, party wall and build without any issues. New bedroom and en-suite are beautiful.

Mike T.

Didsbury, Manchester

Dormer Loft Conversion

★★★★★

We had a hipped roof and weren't sure which conversion type was right. The specialist BestBuilders matched us with assessed our roof, recommended a hip-to-gable with dormer and handled the permitted development application. Couldn't be happier.

Nisha R.

Solihull, Birmingham

Hip-to-Gable Conversion

★★★★☆

Mansard conversion on our London terrace — a complex job in a conservation area. The specialist had done many similar projects nearby and knew exactly what the council would and wouldn't approve. Planning went through first time. Fantastic result.

Georgia F.

Hackney, London

Mansard Conversion

Common Questions

Loft Conversion FAQs

Does a loft conversion need planning permission?

Many loft conversions — particularly dormer and hip-to-gable conversions on houses — fall under Permitted Development (PD) rights in England, meaning no formal planning application is required as long as they stay within specific size, height and material limits. Mansard conversions almost always require full planning permission. Conversions on flats, listed buildings and properties in conservation areas typically also require planning consent. Your matched specialist will confirm what applies for your property and local authority.

How much headroom do I need for a loft conversion?

UK Building Regulations require a minimum of 2m headroom at the highest point for a loft conversion to be classified as habitable space. In practice, specialists look for at least 2.2–2.4m from the floor joists to the ridge to allow for the new floor structure. The headroom available depends on your roof pitch — steeper roofs (common on Victorian and Edwardian properties) convert much more easily. If you're unsure whether your loft has enough height, a specialist will measure up during the initial survey.

How much value does a loft conversion add?

A well-executed loft conversion with an en-suite bathroom can add 15–25% to a property's value in most UK markets. In London and the South East, where moving costs are high relative to property values, the ROI is particularly strong. A bedroom with en-suite is the most valuable configuration — adding a bedroom increases your property's bedroom count and therefore its comparison value. The best ROI comes from conversions that meet Building Regulations and have valid completion certificates.

How long does a loft conversion take?

A straightforward Velux conversion takes 1–2 weeks on site. A dormer conversion typically takes 4–8 weeks. Hip-to-gable and mansard conversions, being more structurally complex, generally take 8–14 weeks. Add planning time (8–10 weeks for a full application) and party wall notice periods (2 months minimum if neighbours don't consent immediately) to the overall programme. Your specialist will give you a detailed timeline at the quoting stage.

Do I need a party wall agreement for a loft conversion?

If your loft conversion involves work on or near a shared wall with a neighbouring property — which is common for terraced and semi-detached houses — you will need to serve a Party Wall Notice under the Party Wall etc. Act 1996. If neighbours consent in writing, the process is straightforward. If they appoint their own surveyor, the agreed process adds cost (typically £800–£2,000) and time. Your loft specialist will advise on whether the Party Wall Act applies to your project and can recommend a party wall surveyor.

Can I stay at home during a loft conversion?

Yes — loft conversions are one of the least disruptive building projects because all the structural work happens above the main living areas. The main interruption is when the new staircase is cut into the floor below, which typically takes 1–2 days. Specialist loft conversion firms are experienced at working in occupied homes and will seal off the work area and manage dust carefully. Most homeowners stay in residence throughout.

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Loft Conversion Specialists Across 519 UK Towns

Each town page shows local loft specialists, town-specific cost ranges and nearby areas.

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Loft Conversion QuotesFrom Vetted UK Specialists

How Much Does a Loft Conversion Cost in the UK?

Convert Your Loft With a Vetted Specialist

How It Works

Every Specialist We List Is:

Which Loft Conversion Suits Your Property?

Terraced & semi-detached houses

End-of-terrace & detached homes

London terraces & city properties

Not sure which type suits your home?

What's Typically Included in a Loft Conversion

🏗 Structural work

🚿 Plumbing & electrics

🪟 Finishing

What Homeowners Say About Our Loft Specialists

Loft Conversion FAQs

Loft Conversion Specialists Across 519 UK Towns

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