In 2026, the “race for space” in the UK has reached a new peak. With the average cost of moving house—factoring in Stamp Duty, estate agent commissions, and legal fees—often exceeding £50,000, homeowners are increasingly looking up.
A loft conversion remains the most efficient way to add a master suite, home office, or extra bedroom. However, as material costs and labour rates have shifted, understanding the current financial landscape is essential. Here is a comprehensive breakdown of loft conversion costs in the UK for 2026.
1. Average Costs by Conversion Type (2026)
The single biggest variable in your budget is the type of conversion you choose. This is largely determined by your property’s existing roof structure and your desired head height.
| Conversion Type | Typical Cost Range | Average Duration | Best For |
| Velux (Rooflight) | £25,000 – £40,000 | 4 – 6 Weeks | High-pitched roofs; minimal disruption. |
| Dormer (Rear) | £45,000 – £65,000 | 6 – 10 Weeks | Semi-detached and terraced homes. |
| Hip-to-Gable | £55,000 – £75,000 | 8 – 12 Weeks | 1930s-style semi-detached properties. |
| L-Shaped Dormer | £60,000 – £85,000 | 10 – 14 Weeks | Victorian terraced homes with rear wings. |
| Mansard | £70,000 – £100,000+ | 12 – 16 Weeks | Urban areas; maximum space gain. |
2. Itemised Cost Breakdown
To help you budget accurately, it is important to see where the money actually goes. For a standard 30$m^2$ Dormer Conversion, a typical 2026 budget looks like this:
The Shell & Structure (Approx. 50%)
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Scaffolding: £3,500 – £5,000 (depending on height and duration).
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Steel Beams (RSJs): £4,000 – £7,000 (essential for supporting the new floor and roof).
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Roofing & External Cladding: £6,000 – £9,000.
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Insulation: £1,500 – £3,000 (meeting 2026 Future Homes Standard thermal requirements).
Internal Fit-Out (Approx. 35%)
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Staircase: £1,500 (Standard) – £4,500 (Bespoke/Glass).
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Windows (Velux or Dormer): £2,500 – £5,500.
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Electrical & Plumbing: £3,000 – £6,000 (First and second fix).
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En-suite Bathroom: £5,000 – £10,000 (including tiling and sanitaryware).
Professional Fees & Admin (Approx. 15%)
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Architectural Drawings: £1,500 – £3,500.
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Structural Engineer Calculations: £800 – £1,500.
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Building Regulations Fees: £800 – £1,200.
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Party Wall Agreements: £1,000 – £2,500 per neighbour (if required).
3. Regional Price Variations
Location remains a massive factor. If you are converting a loft in London or the South East, expect to add a 15% to 25% premium onto national averages due to higher labour costs, skip permits, and parking bay suspensions.
2026 Pro Tip: Builders in the North of England and Scotland currently offer the most competitive rates, with projects often coming in 10% below the national average.
4. Real-World Examples
Example A: The “London Master Suite”
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Property: Victorian Terrace, Hackney.
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Type: L-Shaped Dormer.
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Spec: Master bedroom, walk-in wardrobe, high-spec en-suite, Juliet balcony.
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Total Cost: £92,000 (Inc. VAT).
Example B: The “Suburban Office”
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Property: 1950s Semi-detached, Manchester.
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Type: Rear Dormer.
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Spec: Home office, guest bedroom, standard Velux window to the front.
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Total Cost: £52,000 (Inc. VAT).
Example C: The “Budget Velux”
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Property: Detached with high pitch, Bristol.
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Type: Velux-only (Rooflight).
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Spec: Open-plan hobby room, no plumbing, standard staircase.
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Total Cost: £29,500 (Inc. VAT).
5. Factors That Can Blow Your Budget
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Low Head Height: If your existing loft is under 2.2m at the highest point, you may need to “raise the roof” or “lower the ceilings” of the rooms below, adding £15,000+ to the bill.
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The “Water Tank” Issue: Moving old header tanks to accommodate the new room often requires a new unvented boiler system (£2,500 – £4,000).
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Party Wall Disputes: If a neighbour refuses to sign a notice, a formal award involving two surveyors can add thousands in fees before a single brick is laid.
