Loft conversion cost UK 2026
A loft conversion is the single best-value way to add a bedroom to a UK home — typically returning around 20 % to the property's value while costing 30–60 % less than an extension. This guide breaks down real 2026 prices for every common type, what affects them, and how to keep the bill down.
How much does this cost in the UK in 2026?
The typical UK price range is £30,000–£95,000, with the average household paying around £50,000. Use the free calculator below to get a personalised estimate.
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What affects the cost?
- Conversion type — Velux conversions are the cheapest, mansard the most expensive
- Roof height — anything under 2.2 m at the ridge usually means a dormer or raising the roof
- Whether you add an en-suite (typically £8,000–£12,000 on top)
- Staircase position — using an existing stairwell saves £2,000+ vs cutting a new one
- Region — London adds ~35 %, the North saves ~10 %
- Spec — bespoke joinery, hardwood floors and high-end glazing push the price up fast
- Whether building control + an architect are bundled or quoted separately
Cost breakdown
| Item | Low | High |
|---|---|---|
| Structural works (joists, steels, dormer build) | £12,000 | £28,000 |
| Roofing, tiling, weatherproofing | £3,500 | £8,000 |
| Insulation, plasterboard, plastering | £2,500 | £5,500 |
| Staircase + flooring | £2,000 | £5,000 |
| Electrics + plumbing | £1,500 | £3,500 |
| Velux windows (per window) | £900 | £1,800 |
| En-suite (optional) | £8,000 | £12,000 |
| Architect + building control + party wall | £2,500 | £5,000 |
Cost by UK region
Regional pricing varies by up to 50 %, mostly driven by labour rates. These multipliers apply to the base UK cost:
| Region | Multiplier | Typical cost |
|---|---|---|
| London | 1.35× | £67,500 |
| South East | 1.25× | £62,500 |
| South West | 1.10× | £55,000 |
| Midlands | 1.00× | £50,000 |
| North England | 0.90× | £45,000 |
| Scotland | 0.95× | £47,500 |
| Wales | 0.90× | £45,000 |
| Northern Ireland | 0.92× | £46,000 |
Planning permission?
Usually permitted development (no permission), unless your home is listed or in a conservation area
How long does it take?
5–10 weeks typical, plus design and approvals time beforehand.
DIY vs Professional
Difficulty: Pro required. UK building regulations and Part P/Gas Safe rules mean most of this work must be done by registered professionals. Even where DIY is permitted, paying a pro is usually faster and more reliable.
How to save money
- Get at least three written quotes — the spread between cheapest and dearest is often 25 %
- Use a fixed-price contract with stage payments tied to milestones
- Reuse the existing landing for the staircase if possible
- Buy your own Velux windows direct from a builders merchant — typically 10–20 % cheaper than the builder's mark-up
- Avoid bespoke joinery where IKEA or Howdens fitted wardrobes would do
How to find a trusted tradesperson
Always get at least three written quotes. Use a vetted UK trade network for peace of mind:
- Checkatrade — vetted local trades with reviews
- MyBuilder — reviewed builders by job type
- Bark — get quotes from local pros
Or use the calculator above to get 3 free quotes direct to your inbox.
Frequently asked questions
Do I need planning permission for a loft conversion?
Most loft conversions fall under permitted development if you stay within the volume limits (40 m³ for terraces, 50 m³ for semis and detached). You will still need building regulations approval, and your neighbours’ party wall consent if you share a wall.
How long does a loft conversion take?
A Velux conversion is typically 5–6 weeks; a dormer is 7–9 weeks; a mansard or L-shape can take 10–12 weeks. Add 4–8 weeks for architect drawings and building control sign-off beforehand.
Will a loft conversion add value to my home?
Yes — Nationwide and Zoopla studies consistently show a loft conversion adds 15–25 % to a UK home’s value, especially when it adds a usable bedroom and en-suite. The uplift is highest in London and the South East.
What head height do I need for a loft conversion?
Building regulations require a minimum 2 m clear head height over the staircase landing and most of the usable floor. If your existing ridge height is under about 2.2 m you will likely need to raise the roof (dormer or hip-to-gable).
Can I live in my home during a loft conversion?
Yes — most loft conversions are done with the family in place. The biggest disruption is the staircase-cutting week and any time the roof is open. Expect noise from 8 am, plus 2–3 days where the upstairs is sheeted off.
What is the cheapest type of loft conversion?
A Velux (rooflight) conversion is the cheapest at £30,000–£55,000 for a typical UK home because no roof reshaping is needed. The trade-off is less head height than a dormer.
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Disclaimer: Prices are guide ranges based on 2026 UK market data. Get quotes from local tradespeople for accurate pricing.
Costs by type
Dormer Loft Conversion Cost UK 2026
£38,000 – £85,000
A dormer loft conversion adds a vertical-walled extension out of the roof slope, dramatically increasing usable head height…
Hip-to-Gable Loft Conversion Cost UK 2026
£45,000 – £90,000
A hip-to-gable conversion changes a hipped roof end into a vertical gable, typically combined with a rear dormer…
L-Shaped Loft Conversion Cost UK 2026
£55,000 – £95,000
An L-shaped loft uses the main roof plus the rear-extension or back addition roof to create an L-shaped…
Loft Conversion Cost by Region UK 2026
£27,000 – £85,000
Loft conversion costs vary by up to 50 % across the UK, with London the most expensive and…
Mansard Loft Conversion Cost UK 2026
£55,000 – £110,000
A mansard conversion changes the whole roof slope to near-vertical, maximising headroom and floor area. It's the gold…
Velux Loft Conversion Cost UK 2026
£30,000 – £60,000
A Velux (rooflight) loft conversion is the cheapest way to convert a UK loft because the roof shape…
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