A cheap quote is not always a fair quote. Loft conversions vary more in price than almost any other building work — the type you choose changes the cost more than the finish level does. Here’s what each type genuinely costs, with real prices, not marketing ranges.
Loft Conversion Cost UK 2026: All Types Compared, Every Zone
Types of Loft Conversion Covered on This Page
- Velux (rooflight) conversion — no structural roof alteration, cheapest option
- Dormer conversion — adds a box-shaped extension to the roof, most common in the UK
- Hip-to-gable conversion — extends a hipped roof into a vertical gable end, adds significant headroom
- Mansard conversion — most extensive structural change, near-full floor of usable space
Four Price Levels, Four Sub-Levels Each
| Level | Sub-level | Base UK price (£/m²) | What it means |
|---|---|---|---|
| Budget | 1 | £1,950 | Entry-level materials, local contractor, minimal spec |
| Budget | 2 | £2,250 | Slightly improved finish, still basic |
| Budget | 3 | £2,550 | Upper budget tier |
| Budget | 4 | £2,850 | Top of budget |
| Standard | 1 | £2,950 | Mid-market entry, typical UK contractor |
| Standard | 2 | £3,150 | Good materials, standard fittings |
| Standard | 3 | £3,350 | Most common choice for family lofts |
| Standard | 4 | £3,650 | Upper standard, better finish |
| Premium | 1 | £3,850 | Quality materials, experienced contractor |
| Premium | 2 | £4,150 | Full compliance, upgraded structural work |
| Premium | 3 | £4,450 | Higher-spec insulation and glazing |
| Premium | 4 | £4,750 | Top of premium tier |
| Luxury | 1 | £5,000 | Architect-led, top specification |
| Luxury | 2 | £5,400 | Full project management |
| Luxury | 3 | £5,850 | Bespoke design elements, en-suite ready |
| Luxury | 4 | £6,300+ | High-end residential, no compromises |
Source: DEH & P Extension & Loft Conversion Price Guide, June 2026. Base UK-average prices before regional adjustment. Loft prices run higher per m² than extensions because of roof structural work, insulation upgrades, and staircase installation costs baked into every level.
Regional Zone Multipliers
| Zone | Multiplier | Covers |
|---|---|---|
| London Zone 1–2 | ×1.5 – 1.8 | Mayfair, Chelsea, Kensington, Westminster |
| London Zone 3–4 | ×1.3 – 1.5 | Clapham, Fulham, Hackney, Battersea |
| London Zone 5–6 | ×1.1 – 1.3 | Croydon, Barnet, Bromley, Harrow |
| South East England | ×1.0 – 1.2 | Surrey, Kent, Hertfordshire |
| Rest of England | ×0.85 – 1.0 | Midlands, North, South West |
| Scotland / Wales | ×0.80 – 0.95 | Regional adjustment applied |
Worked example: A 25m² dormer loft conversion, Standard level 2, in South East England: £3,150/m² × ~1.1 zone multiplier ≈ £3,465/m² × 25m² = £86,625
Use the calculator tool on this site for your exact postcode and size.
Which Type Should You Choose?
- Velux: cheapest, no planning permission usually needed, but limited headroom — works best if your existing roof pitch is already generous
- Dormer: the UK’s most common choice — adds real headroom and floor space without a full roof rebuild
- Hip-to-gable: only relevant if you have a hipped roof (common on semi-detached and detached houses) — adds substantial usable space
- Mansard: most expensive, most disruptive, but delivers the most additional floor area — often the only option that gets you a genuine extra bedroom with full standing height throughout
What’s Included at Every Level
- Structural roof work appropriate to the conversion type
- Insulation to current building regulations standard
- Staircase installation
- VAT (20%, included in all figures above)
- Contingency: 5% (Budget) / 10% (Standard) / 15% (Premium) / 20% (Luxury)
What’s NOT Included
- En-suite bathroom fit-out (priced separately under Renovation Costs)
- Furniture, appliances, decoration
- Party wall costs where the loft conversion affects a shared wall (common on terraced and semi-detached properties)
- Architect / planning consultant fees — add +12% if you want dedicated architectural drawings and project management (strongly recommended for hip-to-gable and mansard conversions)
Planning Permission & Building Control
- Velux: usually permitted development — check volume limits (normally 40m³ for terraced, 50m³ for detached/semi)
- Dormer: often permitted development within volume limits, but planning permission required if it faces a highway or exceeds allowances
- Hip-to-gable: frequently requires planning permission — changes the roof shape visibly
- Mansard: almost always requires planning permission — the most significant external change of the four types
Building Control sign-off is required for every loft conversion type, regardless of planning permission status — this covers structural safety, fire escape routes, and insulation standards.
Impact on Property Value
A loft conversion that adds a genuine extra bedroom is one of the highest-return building projects available in the UK — particularly in zones where an extra bedroom moves a property into a different buyer bracket. Mansard and dormer conversions that create a full double bedroom with en-suite tend to add the most value relative to cost. See our full Property Value Impact guide for zone-by-zone figures.
Hidden Costs to Budget For
- Staircase relocation if the existing stair position doesn’t align with the new loft layout
- Structural strengthening of the existing floor joists — very common, rarely quoted upfront by cheap contractors
- Fire escape window (Velux conversions in particular)
- Party wall agreement costs on terraced and semi-detached properties
All figures are indicative estimates for budgeting purposes only. Actual costs depend on site conditions, structural survey, planning requirements and contractor pricing. Always obtain at least three written quotes. Costs last reviewed: June 2026. Next review: September 2026.
Want your exact number? Use the free cost calculator on this site — enter your postcode and project size for a precise, zone-adjusted estimate in seconds.