Velux from £20k. Dormer from £35k. Mansard from £55k. The complete regional price breakdown — and the £10,000–£20,000 in extras that most quotes quietly leave out.
The question "how much does a loft conversion cost?" has a genuinely complicated answer — not because the industry is evasive, but because no two loft conversions are the same. Type, region, specification, what the original roof looks like, and what your quote actually includes can swing the final number by £30,000 or more on a comparable project. This guide gives you the real figures, the regional breakdown, and the complete list of extras that keep ambushing homeowners who trusted the headline price.
Before diving into the detail, here is a snapshot of where the UK market sits in 2026. These are national mid-range figures — not London, not the cheapest contractor in the North — and they assume a reasonable specification with Building Regulations compliance included.
Every figure above is a floor, not a ceiling. A full breakdown of what inflates these numbers — and what most quotes leave out entirely — is in Section 4. Before you approach any builder, read that section first.
The type of conversion you choose is the single biggest cost variable. Here is a detailed breakdown of each, including what you get for the money and where the price pressure typically comes from.
| Type | Typical Cost | Build Time | Planning Needed? | Best For |
|---|---|---|---|---|
| Velux | £20,000–£45,000 | 4–6 weeks | Rarely | Simple bedroom / study |
| Dormer (rear) | £35,000–£65,000 | 6–8 weeks | Often PD | Bedroom + en-suite |
| Hip-to-Gable | £40,000–£70,000 | 8–10 weeks | Sometimes | End-terrace, detached |
| Mansard | £55,000–£85,000 | 10–14 weeks | Almost always | Maximum floor area |
| L-Shaped Dormer | £60,000–£100,000 | 10–14 weeks | Sometimes | Two new rooms |
Velux skylights are fitted flush into the existing roof pitch without altering the roofline at all. This is the fastest, cheapest route — and the one most likely to fall comfortably within Permitted Development rights. The key limitation is headroom: the existing loft must already have at least 2.2m of ridge height. Many UK homes built between 1960 and 1985 were constructed with trussed rafter roofs that have insufficient headroom for any conversion — and this is frequently only discovered once contractors are on site.
A well-specified Velux conversion for a single bedroom with flooring, insulation, electrics, a fixed staircase and Building Regulations sign-off should come in at £25,000–£38,000 outside London. Quotes below £20,000 almost always involve compromises on insulation specification, electrics, or the staircase quality — all of which will cost more to fix later than they cost to do properly now.
A dormer projects a box-shaped structure from the rear slope of the roof, adding both headroom and floor area in a single operation. It is the most common loft conversion type in the UK because it offers the best balance of cost, usable space, and planning simplicity. Most rear dormers qualify under Permitted Development rights provided they meet volume and height thresholds.
The "sweet spot" that consistently delivers the best return on investment is a bedroom with a rear-facing en-suite bathroom. Adding a bathroom to a loft conversion adds approximately £4,000–£9,000 to the build cost, but the value uplift it delivers — moving the property into a higher buyer tier — comfortably outpaces that investment in most UK regions.
A dormer conversion quoted at £28,000–£32,000 should raise immediate questions. At that price point, items like structural engineer fees, Building Regulations inspections, scaffold erection and removal, and the fire door upgrades required for a three-storey home are very likely to have been left out of the quoted scope. Ask for a full itemised breakdown of inclusions and exclusions before comparing prices.
On end-of-terrace or detached properties with a hipped roof, one of the sloping sides is extended outward to create a vertical gable wall. This unlocks significant additional floor area — particularly valuable when combined with a rear dormer, which is the most common configuration. The planning position varies by local authority; some permit hip-to-gable extensions under PD rights, others require a formal application. Always confirm with your LPA before committing to a specification.
A mansard replaces the rear roof slope with an almost-vertical wall (typically angled at 72°), creating near-full ceiling height across the entire loft footprint. It is the highest-cost, highest-specification option — common in Victorian and Edwardian terraces and in London's inner boroughs — and almost always requires full planning permission because it changes the roofline substantially. If your priority is creating the largest possible habitable space and budget is less of a constraint, a mansard delivers it. If budget is the primary consideration, it is rarely the right first choice.
Where a rear single-storey extension already exists, an L-shaped dormer extends over both the main roof and the extension flat roof simultaneously. This produces considerably more floor area than a standard dormer and is frequently used where the brief requires two new rooms — a bedroom plus a study, or a master suite plus a child's bedroom — without the cost and complexity of a full mansard. The structural interface between the two roof levels requires careful detailing, and this is an area where an experienced structural engineer adds real value.
Regional variation in loft conversion costs is substantial — not simply a function of London vs. everywhere else, but a more granular picture that reflects labour costs, material transport, planning department workloads, and local market competition. The following figures reflect 2025–2026 market rates for a standard bedroom-plus-en-suite dormer conversion.
| Region | Velux | Rear Dormer | Mansard |
|---|---|---|---|
| Central London | £55,000–£75,000 | £70,000–£120,000 | £100,000–£160,000+ |
| Outer London | £42,000–£64,000 | £55,000–£95,000 | £80,000–£130,000 |
| South East England | £30,000–£50,000 | £45,000–£75,000 | £60,000–£100,000 |
| South West England | £28,000–£45,000 | £40,000–£65,000 | £55,000–£85,000 |
| Midlands | £24,000–£40,000 | £35,000–£55,000 | £50,000–£75,000 |
| North of England | £22,000–£38,000 | £32,000–£52,000 | £48,000–£70,000 |
| Wales | £22,000–£38,000 | £32,000–£52,000 | £48,000–£68,000 |
| Scotland | £20,000–£35,000 | £30,000–£50,000 | £45,000–£65,000 |
| Northern Ireland | £18,000–£32,000 | £28,000–£46,000 | £42,000–£60,000 |
The gap between London and the rest of the UK is driven by four compounding factors: higher skilled labour day rates (London tradespeople typically earn 30–50% more than equivalents in the Midlands or North), higher material delivery costs in dense urban areas, more complex planning and building control environments, and the fact that London's loft conversion market is dominated by a smaller number of specialist firms operating at higher margins than generalist builders in less competitive markets.
There is also a London-specific complication that catches homeowners out: the number of properties in conservation areas, under Article 4 Directions, or subject to local heritage constraints is disproportionately high. Any of these can restrict or remove Permitted Development rights entirely, adding a planning application (8–12 weeks, £200–£500 application fee) to a project that would have been straightforward elsewhere in the country.
Scotland operates its own building control framework. A Building Warrant from the local authority is the statutory equivalent of Building Regulations approval in England and Wales — and it is legally required for all loft conversions without exception. Scottish fire safety regulations for tenements and mid-terraced properties can differ from those in England, and a structural engineer or architect familiar with Scottish building standards is strongly advisable rather than an optional luxury. Costs in Scotland are generally 15–25% lower than the English Midlands, but Building Warrant fees and the requirement for a Completion Certificate add procedural steps that should be factored into the project timeline.
Beyond type and region, loft conversion costs are shaped by a set of variables that are worth understanding before you approach builders — because they affect both what you are quoted and what you should expect to pay.
The specification of finish, flooring, bathroom sanitaryware, windows, and insulation quality varies enormously between projects at similar headline prices. A dormer quoted at £40,000 might include Velux-standard double-glazed timber windows, 150mm PIR insulation, and engineered oak flooring. A dormer quoted at £39,500 might include uPVC windows, 100mm mineral wool insulation, and laminate flooring. The rooms look similar on the day the scaffolding comes down. They do not feel similar in August or January, or on the morning a surveyor values your property.
The staircase is often one of the most underbudgeted items in a loft conversion. A standard straight flight may cost £1,500–£2,500. A space-saving alternating tread staircase runs £1,500–£3,000. A bespoke joinery staircase with glass balustrade can reach £8,000–£15,000. More importantly, where the staircase lands in the floor below it — and how much space it takes from the existing first-floor landing or bedroom — is a design decision that should be made by an architect at the start of the project, not resolved by a builder with a tape measure midway through.
Each additional bathroom adds roughly £4,000–£9,000 to the project cost, including sanitaryware, tiling, plumbing first and second fix, and ventilation. A partition wall between bedroom and en-suite adds £600–£1,200. Skylights for a bathroom (a Velux INTEGRA® electrically operated unit, for instance) add £800–£1,500 per window. None of this is unusual or unreasonable — but it needs to be in the quote from the start, not added as a variation once work has begun.
If the existing roof covering needs to be replaced — which it often does when the roofline is disturbed for a dormer — the cost of re-roofing the relevant section (typically £2,000–£6,000) can be included in the project quote or charged separately. On older properties, lead flashings, ridge tiles, or underlying felt may also need attention. Ask your contractor to inspect the full roof condition before quoting and confirm what is and is not included in their price for the disrupted sections.
The financial case for a loft conversion versus moving to a larger property is, in most UK regions and in most property markets since 2020, strongly favourable to converting. Here is the honest comparison.
| Factor | Moving House | Loft Conversion |
|---|---|---|
| Transaction costs (stamp duty, legal, removal) | £15,000–£35,000 | £0 |
| Project cost | None (but price increase of new property) | £35,000–£85,000 |
| Value created | None — it's a purchase | £15,000–£150,000+ |
| Stamp Duty on higher-value property | Yes — significant | No |
| Disruption to daily life | Very high | Moderate (stay in home) |
| Garden, neighbours, location retained | No | Yes |
A well-specified loft conversion typically adds 10–20% to a property's market value. In cash terms, this means:
| Region | Typical Uplift (%) | Cash Value Added |
|---|---|---|
| Inner London | 15–20% | £75,000–£150,000 |
| South East | 10–15% | £40,000–£80,000 |
| Midlands | 8–14% | £20,000–£50,000 |
| North of England | 6–12% | £12,000–£35,000 |
| Scotland | 8–14% | £15,000–£40,000 |
Every one of these figures assumes the conversion is fully signed off under Building Regulations, with a Completion Certificate issued. A conversion without a Completion Certificate — regardless of how well it looks or how much was spent — cannot be legally valued as a habitable room by any surveyor, RICS or otherwise. It will create problems on any future sale and may affect your mortgage. This is not a technicality. It is the difference between an asset and a liability.
GetMaster vets every loft conversion specialist before they receive a single enquiry — ID checks, qualification verification, and real reviews from real homeowners. Fixed-price itemised quotes. No surprises.
Get a Verified Quote →The gap between a first quote and a final invoice is one of the defining experiences of UK home improvement. Here is how to close that gap before work starts.
Measure your ridge height (minimum 2.2m). Identify whether you have a cut rafter or trussed rafter roof — your builder's first task, but useful to know yourself. Commission an asbestos survey if the house predates 1990. None of this costs much, and all of it affects what you should expect to pay.
An architect's drawings give every contractor you approach the same brief to price against — which makes quotes genuinely comparable rather than apples-versus-oranges. A good architect also identifies staircase placement problems, poor natural light, and cramped bathroom layouts before they are committed to a specification that is expensive to change.
Fixed-price only. Any builder who will not commit to a fixed price for a clearly defined specification is telling you something important about how they intend to manage cost risk — which is that they intend to pass it to you. The cheapest quote is not the issue; the scope it prices is the issue. Ask each contractor to list explicitly what is and is not included.
Go through the list line by line. Structural engineer — included? Building Regulations — included? Scaffold — included? Party Wall — who handles it? Asbestos survey — have they seen the roof space? Fire doors — priced? Boiler capacity — assessed? A contractor who answers these questions confidently and in writing is a contractor who has done this properly before.
Ask to see a conversion completed in the last 12 months. Not photographs — the actual room. Speak to that homeowner if possible. A specialist who cannot arrange this, or is reluctant to do so, raises a question that deserves an answer before you hand over a deposit.
The contract must specify: a fixed price with clearly defined provisional sums; a completion date; stage payments tied to measurable milestones (scaffold up, structure watertight, first fix complete, second fix complete, sign-off); and who is responsible for Building Regulations submission and inspections. An initial deposit of no more than 20%.
Final payment should not be made until your snag list is complete and your Building Control Completion Certificate has been issued. This is not adversarial — it is standard practice. Any contractor who objects to a reasonable retention is telling you something about their confidence in finishing the job properly.
Every loft specialist on GetMaster is ID-verified, fully insured, and reviewed by real homeowners. Itemised fixed-price quotes. No mid-project surprises.
Free to use · Verified professionals · UK-wide coverage · No commitment required