How Much Does a Loft Conversion Cost in 2026? [UK Prices + VAT]

A loft conversion is one of the most cost-effective ways to add space and value to your home in the UK. In 2026, the average loft conversion costs between £1,500 and £2,500 per m² inclusive of VAT, according to industry data from Checkatrade and the Federation of Master Builders (FMB). For a typical 30 m² conversion, that means a total project cost ranging from £45,000 to £75,000 including VAT at 20%, though final figures depend on location, complexity, and finish quality.

All prices in this guide include VAT at 20% on labour and materials unless stated otherwise. New-build projects may qualify for zero-rated VAT, but most loft conversions on existing homes attract the standard rate.

Unlike moving house — which now costs an average of £12,000–£25,000 in stamp duty, legal fees, and removals alone — a loft conversion lets you stay where you are while gaining a bedroom, home office, or extra living space. But before you start, you need a clear picture of where every pound goes.

This guide breaks down every cost component, shows how prices vary by region, explains what drives the final bill, and reveals how to save money without cutting corners.

Table of Contents

1. Loft Conversion Cost Overview
2. Cost Breakdown by Conversion Type
3. Regional Cost Differences
4. What Affects the Total Cost?
5. Hidden Costs You Should Budget For
6. How to Save Money on Your Loft Conversion
7. Loft Conversion vs. Moving House
8. Planning Permission and Building Regulations
9. How Suddeco Homes Helps
10. Frequently Asked Questions

Loft Conversion Cost Overview

The most common way to budget for a loft conversion is by cost per square metre. In 2026, UK homeowners should expect to pay:

Sources: Checkatrade Cost Guides 2026; FMB Regional Pricing Survey; HomeOwners Alliance. All construction and labour costs include VAT at 20%.

These figures cover construction, materials, labour, and standard finishes inclusive of VAT. They do not include professional fees, planning costs, or premium fixtures. A basic dormer conversion at the lower end might use standard fittings and a straightforward roof structure, while a high-end conversion with en-suite, bespoke storage, and premium flooring will push toward the upper limit.

For a more tailored estimate, get your free instant render — our platform reads your address and shows what your loft could become, complete with projected costs based on local planning precedents.

Cost Breakdown by Conversion Type

Not all loft conversions are the same. The type you choose has the biggest impact on price.

Velux (Rooflight) Conversion

A Velux conversion is the simplest option. You add windows into the existing roof slope without altering the roofline. It is the cheapest type but also adds the least usable floor space because the headroom is limited by the existing pitch.

Dormer Conversion

A dormer extends vertically from the roof slope, creating a flat-roofed section with full headroom. This is the most popular choice in the UK because it maximises usable space and is suitable for most property types, including terraced houses.

Hip-to-Gable Conversion

This option alters the roof structure by extending the hip (sloped side) into a vertical gable wall. It is common on semi-detached and detached homes with hipped roofs, and it significantly increases internal volume.

Mansard Conversion

A mansard conversion replaces one or both roof slopes with a steep, almost vertical wall and a flat roof section. It offers the most interior space but is the most expensive and typically requires planning permission. It is particularly common in London where maximising space is critical.

Room-in-Roof (Shell-Only)

A shell-only conversion includes the structural work, insulation, electrics, and basic plastering, but leaves the interior fitting — flooring, bathrooms, built-in storage — to the homeowner. It is a good option if you are handy or want to spread costs over time.

Regional Cost Differences

Where you live in the UK has a significant impact on what you will pay. Labour rates, material costs, and demand all vary by region.

London

London commands the highest loft conversion costs in the UK. Expect to pay a 30–50% premium over the national average.

Central London boroughs — especially Kensington & Chelsea, Westminster, and Camden — also have stricter planning rules and a higher likelihood of falling within a conservation area, which can add professional fees and extend timelines.

South East England

The South East — including Surrey, Berkshire, and Buckinghamshire — carries a 20–30% premium.

High demand from commuters and strong property values keep prices elevated, though competition among builders is better than in London.

Midlands & North of England

In the Midlands, North West, North East, and Yorkshire, costs typically run 10–20% below the national average.

Cities like Manchester, Birmingham, and Leeds have a large pool of experienced builders, which helps keep labour costs competitive.

Scotland & Wales

Scotland and Wales offer some of the most affordable loft conversion rates, often 10–20% below the UK average. However, planning procedures differ: in Scotland, permitted development rights are more restrictive, and most loft conversions require a building warrant and planning permission in practice.

Sources: FMB Regional Pricing Survey 2026; Checkatrade Cost Guides.

What Affects the Total Cost?

Several variables push your project toward the top or bottom of the price range. Understanding them helps you make informed trade-offs.

1. Size and Layout

Larger conversions cost more in total but often less per m² because fixed costs (scaffolding, access, design) are spread over a bigger area. A single large dormer is usually cheaper per m² than two small dormers on different slopes.

2. Roof Structure

Traditional cut roofs (with rafters and purlins) are easier and cheaper to convert than modern trussed rafter roofs, which require structural alterations. If your home was built after 1965, it likely has trusses, which adds £3,000–£8,000 (inc. VAT) to the structural work.

3. Staircase Design

Fitting a staircase into a tight loft space can be complex. A straight flight costs £1,000–£2,500 (inc. VAT). A spiral staircase or bespoke design can run £3,000–£7,000 (inc. VAT). If you need to alter the floor below to accommodate the staircase, add another £2,000–£5,000 (inc. VAT).

4. Windows and Light

Standard Velux windows cost £800–£1,500 each supplied and fitted (inc. VAT). Dormer windows or Juliet balconies add more. If your design requires a side window in a terraced house, you may need a party wall agreement, which adds cost and time.

5. Bathroom or En-Suite

Adding a bathroom increases costs by £5,000–£12,000 (inc. VAT) depending on plumbing runs, soil pipe routing, and fixture quality. If the soil pipe needs to drop through multiple floors, budget at the higher end.

6. Finish Quality

Basic finishes — carpet, standard lighting, basic radiator — keep costs down. Premium finishes such as engineered oak flooring, bespoke joinery, underfloor heating, and smart home integration can add £10,000–£25,000 (inc. VAT).

Hidden Costs You Should Budget For

Many homeowners focus on the build cost and forget the extras. These add up quickly. Note: professional fees listed below are typically VAT-exempt or charged at 20% depending on the supplier — always confirm with your professional.

A sensible approach is to add 15–20% on top of your quoted build cost to cover fees, contingencies, and unexpected issues like rot or asbestos discovery.

Sources: HomeOwners Alliance Cost Guide; Planning Portal Fee Schedule 2026.

How to Save Money on Your Loft Conversion

1. Choose the Right Type

If you only need a home office or extra bedroom, a Velux conversion may be enough. Only opt for a mansard or hip-to-gable if you genuinely need the extra space.

2. Get Multiple Quotes

The FMB recommends obtaining at least three detailed quotes from reputable builders. Prices for the same scope can vary by 20–30% between firms. Ensure all quotes clearly state whether they include VAT at 20%.

3. Consider a Shell-Only Build

A shell-only conversion lets you fit out the interior later, spreading costs and potentially doing some work yourself.

4. Use Standard Materials

Bespoke joinery and imported tiles look beautiful but inflate the budget. Standard ranges from major merchants offer excellent quality at half the price.

5. Plan for Permitted Development

If your conversion falls within permitted development rights, you avoid the cost and delay of a full planning application. Our platform checks this instantly for your address — try your free render.

6. Time It Right

Builders are often quieter in January and February. Booking during these months can secure a 5–10% discount compared to spring and summer peak season.

Loft Conversion vs. Moving House

For many families, the choice is between converting and relocating. The numbers often favour staying put.

A loft conversion not only avoids the hassle of moving but can also add 15–20% to your property value, according to the HomeOwners Alliance. On a £400,000 home, that is £60,000–£80,000 in added equity — often more than the cost of the conversion itself.

Planning Permission and Building Regulations

Most loft conversions in the UK fall under permitted development rights, meaning you do not need full planning permission if:

• The conversion adds less than 40 m³ (terraced) or 50 m³ (detached/semi) of additional space
• The extension does not exceed the height of the existing roof
• Side-facing windows are obscure-glazed and non-opening (or open above 1.7 m)
• No verandas, balconies, or raised platforms are added

However, you will still need building regulations approval for structural integrity, fire safety, insulation, and staircase design. This costs £200–£1,000 depending on your local authority.

If you live in a conservation area, a listed building, or an Area of Outstanding Natural Beauty (AONB), permitted development rights may be restricted or removed entirely. In these cases, a full planning application (£462) is required.

Our Design + Planning package includes the planning application, building regulations, structural engineer calculations, and unlimited revisions — all for a fixed fee.

How Suddeco Homes Helps

Traditional loft conversion projects involve months of back-and-forth with architects, weeks waiting for quotes, and uncertainty about what is actually possible on your property. Our platform changes that.

Step 1: Enter your address. Our AI analyses nearby approved planning applications to understand what your local council has already permitted on similar homes.

Step 2: Receive an instant render, floor plans, and a cost estimate — completely free. No appointment, no waiting, no commitment.

Step 3: Choose your package. Our Concept Package delivers three renders, full plans, and one revision within 48 hours for £495–£995 (inc. VAT). Our Design + Planning package handles the full planning application, building regulations, and structural engineering for £2,495 (inc. VAT).

Step 4: Build with confidence. Our Design-to-Build service matches you with vetted builders, includes project management, milestone payment protection, and a 12-month warranty.

Get your free loft conversion render today →

Frequently Asked Questions

How much does a loft conversion cost per m² in the UK?

In 2026, the average loft conversion costs between £1,500 and £2,500 per m² including VAT at 20%. A basic Velux conversion starts at the lower end, while a high-end mansard conversion with premium finishes can reach £3,000 per m². (Source: Checkatrade, FMB)

Is a loft conversion cheaper than an extension?

Generally, yes. A loft conversion typically costs £1,500–£2,500 per m² (inc. VAT), while a ground-floor rear extension costs £1,800–£2,800 per m² (inc. VAT). Loft conversions also use existing structure, avoiding foundation and groundwork costs.

Do I need planning permission for a loft conversion?

Most loft conversions fall under permitted development and do not need full planning permission. However, you still need building regulations approval. If you live in a conservation area or listed building, planning permission is usually required. Check your address on our free render tool for an instant assessment.

How long does a loft conversion take?

A standard dormer conversion takes 6–10 weeks from start to finish. A Velux conversion may take 4–6 weeks, while a complex mansard conversion can take 10–14 weeks. Planning and design add another 4–8 weeks before construction begins.

Will a loft conversion add value to my home?

Yes. According to the HomeOwners Alliance, a loft conversion typically adds 15–20% to a property's value. On a £400,000 home, that is £60,000–£80,000 in added equity.

Can all lofts be converted?

Not all. You need at least 2.2 m of head height at the highest point for a comfortable conversion. If your loft is lower, you may need to lower the ceiling of the room below or raise the roof — both of which add significant cost.

What is the cheapest type of loft conversion?

A Velux (rooflight) conversion is the cheapest, starting at around £1,500 per m² (inc. VAT) or £30,000 for a 20 m² space. It involves the least structural alteration.

Do I need to move out during a loft conversion?

Usually, no. Most homeowners stay in the property during a loft conversion. Scaffolding and construction noise are the main inconveniences. If you have young children or work from home, you might consider temporary relocation during the noisiest 2–3 weeks.

How much does a loft conversion cost in London?

In London, expect to pay a 30–50% premium over the national average. A 30 m² dormer conversion in London typically costs £58,500–£90,000 (inc. VAT), compared to £45,000–£75,000 nationally.

What is included in a standard loft conversion quote?

A standard quote typically includes: structural alterations, insulation, electrics, lighting, plastering, flooring, windows, and a staircase — all with VAT at 20% included. It usually excludes: bathroom fitting, bespoke joinery, furniture, and decoration. Always ask for a detailed breakdown and confirm whether VAT is included.

Can I get a loft conversion under £40,000?

Yes, a small Velux or shell-only conversion in a lower-cost region can come in under £40,000 (inc. VAT). A 20 m² Velux conversion in the North of England might cost £27,000–£32,000. However, be wary of quotes significantly below market rate — they often exclude essential elements, VAT, or use unqualified labour.

How much does a loft conversion with a bathroom cost?

Adding a bathroom or en-suite adds £5,000–£12,000 (inc. VAT) to the total cost. The exact figure depends on the plumbing route, soil pipe access, and fixture quality. If the soil pipe needs to be routed through multiple floors, costs rise toward the upper end.

What is the difference between a dormer and a mansard conversion?

A dormer has a flat-roofed extension projecting from the existing sloped roof. A mansard replaces the entire roof slope with a steep, near-vertical wall and flat roof. Mansards offer more space but cost 20–30% more and usually require planning permission.

Does VAT apply to loft conversions?

Yes. VAT at the standard rate of 20% applies to labour and materials for most loft conversions on existing homes. Some builders quote VAT-inclusive prices; others quote net of VAT. Always confirm which applies. New-build projects may qualify for zero-rated VAT, but this does not typically apply to loft conversions.