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  • Dormer loft conversions from £30,000 nationally
  • Hip-to-gable conversions from £33,000 nationally
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✅ Reviewed by the BestBuilders editorial team on 17 June 2026. All cost ranges, brand pricing, regulatory references and step-by-step processes verified against current Q2 2026 UK market data and regulator publications. Editorial standards: /editorial-standards.
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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 loft conversion 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

1
Tell us your conversion type and postcode
60 seconds. Not sure of the type? Select "Not sure yet" — specialists will advise.
2
We match you with local loft specialists
Up to 3 vetted specialists in your area, within 24 hours.
3
Compare quotes, reviews and timelines
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.

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
2026 Cost Comparison

Loft Conversion Cost by Type and Region (2026)

Live cost ranges from the Best Builders 2026 Cost Index, aggregated across 519 UK towns. Mid-spec finish; excludes architectural and structural engineering fees, kitchen/bathroom fit-out beyond standard spec, and premium glazing or balcony additions.

RegionDormerHip-to-GableMansard
London£47,000 – £81,000£51,500 – £93,000£59,000 – £113,000
South East£42,000 – £72,000£46,000 – £83,000£53,000 – £101,000
Southern£38,000 – £66,000£42,000 – £76,000£48,000 – £92,000
Eastern£37,000 – £64,000£40,500 – £73,500£46,000 – £90,000
West Midlands£35,000 – £60,000£38,500 – £69,000£44,000 – £84,000
East Midlands£35,000 – £60,000£38,500 – £69,000£44,000 – £84,000
Yorkshire£33,000 – £57,000£36,500 – £65,500£41,000 – £80,000
North West£33,000 – £57,000£36,500 – £65,500£41,000 – £80,000
South West£32,000 – £55,000£35,000 – £63,500£40,000 – £77,000
North East£31,000 – £54,000£34,000 – £62,000£39,000 – £76,000
Scotland (North)£32,000 – £55,000£35,000 – £63,500£40,000 – £77,000
Scotland (South)£32,000 – £55,000£35,000 – £63,500£40,000 – £77,000
South Wales£30,000 – £52,000£33,000 – £60,000£38,000 – £73,000
Merseyside & N. Wales£30,000 – £52,000£33,000 – £60,000£38,000 – £73,000

Source: Best Builders 2026 Cost Index · aggregated quote data, refreshed quarterly · Mansard conversions consistently command the highest premium (around 25–35% above dormer equivalents) due to extensive roof rebuild work and London-area planning constraints. See full cost index →

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

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.
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.
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.
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.
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.
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.
Velux (rooflight) keeps the existing roof and adds windows — cheapest, fastest, but limited headroom. Dormer extends the roof outward to add headroom and floor space, the most popular UK choice (£30,000–£81,000 by region). Hip-to-gable converts the sloped hip end of a semi-detached or detached roof into a vertical gable wall — adds significant volume (£33,000–£93,000). Mansard rebuilds one or both roof slopes to near-vertical, maximising floor area but commanding the highest cost (£38,000–£113,000) and usually requiring planning permission.
As a rule of thumb, you need at least 2.2m of clear head height at the highest point of your existing loft before any construction. Building Regulations require 2.0m headroom over stairs and main walking areas in the finished conversion. If you have less than 2.0–2.2m, you may need a roof rebuild (mansard or dormer with raised ridge) or to lower the ceilings of the rooms below — both add £8,000–£25,000 to the project. A free site survey confirms what is possible.
Almost always yes for terraced and semi-detached homes. Loft conversions typically involve cutting into the party wall to install steel beams, which triggers the Party Wall etc. Act 1996. Serve a Party Wall Notice at least 2 months before work starts. If your neighbour disagrees or doesn't respond, you'll need a surveyor (£700–£2,500 per side, usually paid by you). Detached homes generally avoid this requirement unless excavating within 3m of a neighbour's foundation.
Yes — most loft conversions are financed via a further advance on your existing mortgage, remortgaging to release equity, or a secured home improvement loan. Typical further-advance rates in 2026 sit around 4.5–6.5%. Lenders usually want build cost quotes, planning evidence, and a chartered surveyor valuation showing the post-conversion property value. Because loft conversions reliably add 15–25% to home value, lenders view them favourably and the increased equity often covers the borrowing on completion.
Insurance: notify your home insurer before work starts — they may add an endorsement or require Contractor's All-Risks (CAR) cover during the build. After completion, update your sum insured to reflect the higher rebuild cost (typically +£40,000–£80,000). Council Tax: banding is only reassessed on sale or a "material change"; a loft bedroom conversion usually doesn't trigger reassessment for current owners, but adding a self-contained annexe with kitchen and bathroom may.
The snagging period is the time after practical completion when your builder fixes minor defects — cracked plaster, sticking doors, sealant gaps, paint touch-ups. Industry standard is 12 months from completion, with most snags surfacing in the first 6 weeks as heating cycles dry out the build. Withhold 2.5–5% of the contract value as a retention, released at end of snagging. For projects over £40k, consider an independent surveyor for the formal snagging inspection.
Yes — UK Building Regulations Part B (fire safety) require that a loft conversion creating a new third storey has a protected escape route. This means: fire-rated doors (FD30) with self-closers on all rooms opening onto the stairwell, mains-wired interlinked smoke alarms on every floor, fire-resistant ceilings and stair structure, and (for some configurations) a sprinkler system. Your builder includes this in the standard build cost; expect £2,500–£5,000 for the full Part B package.
Modestly. Modern loft conversions are built to current UK Building Regulations Part L insulation standards — typically U-values of 0.18 W/m²K for the roof and 0.28 for walls, well above older parts of the house. Net heating-cost impact for a typical loft bedroom is £150–£350/year, often offset by improved insulation reducing heat loss through the original roof. Adding an en-suite increases hot water demand — discuss with your installer whether your boiler needs upgrading.
Best Builders matches homeowners with vetted, insured loft conversion specialists across all 519 UK towns in our network — London, Home Counties, Midlands, North, Scotland and Wales. Each town page shows verified specialists local to your postcode plus typical regional cost ranges. If your postcode is outside main coverage, we still send your enquiry to qualified builders willing to travel, though availability may be limited.

Our sources for this guide

Cost ranges, timelines and regulatory information on this page are compiled from:

Editorial standards & how to reach us

This page is maintained by the Best Builders editorial team. Cost figures are reviewed quarterly against active quote data from our verified UK builder network. Regulatory information (planning, Building Regs Part B and Part L, Party Wall) is checked against current UK government guidance at each refresh. We do not accept payment for editorial coverage; builder listings are earned through our vetting process.

If you spot an error or have feedback, email editorial@bestbuilders.co.uk.

Last updated: 23 May 2026 · Next scheduled review: 23 August 2026

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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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