How Much Does a Loft Conversion Cost in the UK? (2026 Price Guide)

Thinking about converting your loft instead of moving house? You're far from alone — loft conversions remain one of the most popular ways for UK homeowners to add space and value without the cost, stress and stamp duty of relocating. But before you get too far into floor plans and Pinterest boards, you need a realistic number: how much does a loft conversion actually cost in 2026?

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The short answer: loft conversion costs in 2026

Most UK loft conversions cost between £1,400 and £2,800 per square metre, depending on the type of conversion, your location and the finish you choose. For a typical semi-detached or terraced house, that works out as follows:

Conversion Type	Typical Size	Estimated Cost (Standard Finish)	Estimated Cost (Premium Finish)
Rooflight / Velux	20-25m²	£25,000 – £40,000	£45,000 – £55,000
Dormer	25-35m²	£40,000 – £55,000	£60,000 – £80,000
Hip-to-gable	30-40m²	£48,000 – £65,000	£70,000 – £95,000
L-shaped / combination	35-50m²	£60,000 – £85,000	£90,000 – £120,000+
Mansard	35-50m²	£65,000 – £95,000	£100,000 – £140,000+

These figures typically cover the structural build, staircase, insulation, first-fix electrics and plumbing, and a standard bathroom or en-suite where included. They usually exclude VAT, architect and structural engineer fees, party wall costs, and higher-spec fixtures and finishes.

Types of loft conversion and what drives the price

Rooflight (Velux) conversion

The cheapest and simplest option, because it doesn't alter the shape of the roof. You're essentially insulating, boarding and lining the existing loft space and adding rooflight windows, a staircase and services. If your loft already has reasonable headroom (see below), this is often the most cost-effective way to add a bedroom and bathroom.

Dormer conversion

The most common type in the UK. A dormer extends vertically from the existing roof slope, creating a box-shaped extension that adds significant headroom and usable floor space. Dormers cost more than a simple rooflight conversion because they involve more structural alteration, but they typically add more value and more genuinely usable space per pound spent.

Hip-to-gable conversion

Common on semi-detached and detached houses with a hipped (sloped) roof end. The hipped end is extended outwards to a vertical gable wall, which significantly increases the internal volume. Often combined with a rear dormer for maximum space — this combination is sometimes priced and marketed as an "L-shaped" conversion.

Mansard conversion

The most expensive and most involved option, replacing one or both roof slopes with a near-vertical wall and a flat roof. Mansards deliver the most additional space and headroom of any loft conversion type, but involve the most structural work, scaffolding and time — and are more likely to require full planning permission rather than falling under permitted development.

What affects the final price

The per-square-metre ranges above are a starting point, not a quote. The actual price for your loft depends on:

• Existing headroom — You typically need at least 2.2m from the floor to the ridge for a straightforward conversion. Less than that, and the builder may need to lower the ceiling below or raise the roof, adding significant cost.
• Roof structure — A traditional cut-roof (rafters and purlins) is generally easier and cheaper to convert than a modern trussed roof, which often needs the trusses replaced with steel beams to open up the space.
• Staircase location — Fitting a new staircase without eating into a bedroom below is one of the most common design challenges, and sometimes the most expensive one.
• Bathroom or en-suite — Adding plumbing to a loft (especially for a shower with decent water pressure) adds cost, particularly if it's a long way from existing pipework.
• Party wall agreements — If you share a wall with a neighbour (typical for terraced and semi-detached houses), you'll likely need a party wall agreement, which adds time and a few hundred pounds in surveyor fees.
• Structural work below — Some loft conversions need additional support built down through the house to the foundations, which is far more disruptive and costly than work confined to the loft itself.
• Region — As with extensions, London and the South East typically run 20-40% above the national average; the North of England, Wales, and Scotland tend to sit at or below it.

Loft conversion regional price guide

Region	Approx. cost per m²
London	£2,000 – £2,800
South East	£1,800 – £2,400
South West	£1,600 – £2,100
Midlands	£1,400 – £1,900
North of England	£1,400 – £1,800
Scotland & Wales	£1,400 – £1,800

Check your loft conversion quote before you sign

Loft conversion vs. extension: which costs less?

Per square metre, a loft conversion is usually cheaper than a ground-floor extension, because you're not pouring new foundations or building up from scratch — you're working within the existing roof structure. If you're weighing up both options, our house extension cost guide breaks down ground-floor extension pricing so you can compare like for like. In practice, many homeowners end up choosing a loft conversion specifically because it delivers a similar amount of usable space for meaningfully less money and less disruption to daily life during the build.

Hidden and additional costs to budget for

Beyond the headline build cost, budget for:

• VAT at 20% on most loft conversion work (unless your specific circumstances qualify for a reduced rate)
• Architect or design fees — typically 8-15% of the build cost if you use one
• Structural engineer's calculations — usually required for building control sign-off, a few hundred to low thousands depending on complexity
• Building control fees — a few hundred pounds, paid to your local authority or an approved inspector
• Party wall surveyor fees — if an agreement is needed, typically £700-£1,500 per surveyor
• Scaffolding — often quoted separately, particularly for dormer and mansard conversions
• Skip hire and waste removal
• Decorating, flooring and fitted furniture — many quotes stop at plastered walls and a boarded floor
• A contingency of 10-15% for anything uncovered once the roof is opened up

How to keep loft conversion costs down

• Get at least three detailed quotes from builders who specialise in loft conversions specifically, not just general building work
• Choose a rooflight conversion over a dormer if your existing headroom allows it — you'll save a meaningful amount versus altering the roof shape
• Be realistic about the staircase early in the design process, since moving it later is expensive
• Avoid moving the bathroom far from existing plumbing runs
• Time your project outside of peak season (spring and early summer are typically the busiest and most expensive months for loft specialists)

Questions to ask before you commit

Before accepting a loft conversion quote, make sure you understand exactly what's included. Our guide on how to check a builder's quote walks through this in detail, but at a minimum, confirm:

• Whether the quote is based on a rooflight, dormer, hip-to-gable or mansard design — the price difference between these is substantial
• Whether party wall costs, building control fees and a structural engineer are included or excluded
• Whether the staircase, insulation, first-fix electrics and a bathroom (if wanted) are included in the headline price
• What happens if headroom or roof structure turns out to be worse than expected once work starts

It's also worth checking whether you actually need planning permission before you budget — many loft conversions fall under permitted development, but not all, and getting this wrong can be expensive to unwind. And before signing anything, it's always worth knowing how to check a builder is legitimate and watching for common quote red flags.

How Chat to Your Builder can help

Not sure whether your loft can even be converted, or whether the quotes you've received stack up? Our independent builders can:

• Give you an honest read on whether your loft has enough headroom and the right roof structure for a straightforward conversion
• Talk you through which type of conversion suits your property and budget
• Review quotes you've already received and flag anything missing or overpriced
• Explain what building control and party wall steps you'll actually need

Whether you're in London, Bristol, Manchester, or Leeds, a 30-minute consultation costs just £59 — with a written report and one-to-one call within 24 hours.