Loft Conversion Cost UK 2026 – Prices, Types and Complete Guide

Loft conversion costs vary depending on the conversion type, property size, structural requirements, and level of finish. Whether you are weighing a simple Velux conversion (from £15,000) or a full Mansard extension (up to £70,000), this guide breaks down typical UK prices, project timelines, and how much value a conversion can add to your home. Based in Manchester, LAMTANS Engineering supports homeowners nationwide with expert guidance on planning, insulation, and budgeting for Dormer, Hip-to-Gable, Mansard, and Room-in-Roof conversions.

How Much Does a Loft Conversion Cost in the UK?

Loft conversion costs in the UK vary depending on the conversion type, property size, structural requirements, and level of finish. Whether you are considering a simple Velux conversion or a larger Dormer, Hip to Gable, or Mansard upgrade, understanding the typical costs, timelines, and value added can help you plan your project with confidence.

Type	Typical Cost Range	Timeline	Adds to Property Value
Velux (roof windows)	£15,000 – £25,000	2-3 weeks	5-10%
Dormer	£25,000 – £45,000	4-6 weeks	10-15%
Hip to gable	£35,000 – £55,000	6-8 weeks	10-15%
Mansard	£45,000 – £70,000	8-10 weeks	15-20%
Room in roof (upgrade)	£10,000 – £20,000	3-5 weeks	5-10%

These estimates typically include structural alterations, insulation, electrics, heating, plastering, flooring and finishing. Extras such as an ensuite bathroom (£5,000–£10,000+) or upgraded dormer windows (£3,000–£6,000+) add to the total. Figures are typical estimates confirmed after a free survey.

What Affects Loft Conversion Cost in the UK?

The final loft conversion cost depends on several factors beyond the type of conversion you choose. Property structure, available space, roof design, access requirements, and finishing choices can all affect the overall budget. Understanding these factors helps homeowners plan more accurately before starting their project.

Property Type and Location

The size, age, and layout of your property can significantly influence conversion costs. Terraced homes may require more careful planning due to limited space and restricted access, while semi-detached and detached properties often provide more flexibility for larger loft conversions.

Roof Structure and Design

The existing roof structure plays a major role in determining complexity and cost. Traditional cut roofs are usually easier to adapt, while modern trussed roofs may require additional structural alterations, including steel supports, which can add around £2,000–£5,000 to the project cost.

Available Headroom

Adequate headroom is essential for creating a comfortable living space. If your loft has limited height (typically below around 2.2m), additional work such as a dormer or mansard conversion may be required to maximise usable space and increase the overall cost.

Staircase Installation and Access

A permanent staircase is usually required for a compliant loft conversion. Costs can vary depending on the staircase design and where it connects with the existing floor layout, with typical installations costing around £2,000–£4,000.

Choice of Interior Finish

The level of finishing has a major impact on the final budget. A standard conversion with plastering, basic electrics, and flooring will cost less than a premium finish featuring ensuite bathrooms, bespoke storage, smart lighting, or underfloor heating.

Detailed Cost Breakdown by Loft Conversion Type

The cost of a loft conversion varies significantly depending on the design, structural changes required, and level of finish. Below is a breakdown of the most common loft conversion types, including typical prices, suitability, and what is usually included within the project cost.

Velux (Roof Windows) £15,000–£25,000

The most affordable option — it uses the existing roof structure with minimal change, installing roof windows into the slope for a brighter, more functional loft.

Best for

• Homes with ~2.2m+ existing headroom
• A simple, cost-effective conversion
• Properties needing no major roof alterations

Typically included

• Roof windows installation
• Floor reinforcement where required
• Insulation between & over rafters
• Staircase (if required)
• Plastering & decoration
• Electrics & lighting
• Heating (radiators or underfloor)

Usually not included: ensuite bathroom, dormer structure, major roof-shape changes.

Dormer £25,000–£45,000

Extends vertically from the existing slope to create headroom and floor space — one of the most popular types for the significant increase in living area.

Best for

• Terraced & semi-detached homes
• Properties with limited headroom
• Bedrooms, offices or larger living spaces

Typically included

• Dormer structure (flat or pitched roof)
• New windows
• Structural floor strengthening
• Staircase
• Full insulation upgrade
• Electrics, lighting & heating
• Plastering & finishing
• Building control approval

Typical example: a standard 3-bed semi often falls within £30,000–£35,000 depending on specification.

Hip to Gable £35,000–£55,000

Changes the sloping side of a hipped roof into a vertical gable wall, creating additional internal space and improving usability.

Best for

• Detached & semi-detached homes
• Properties with hipped roofs
• Homeowners wanting more space than a standard dormer

Typically included

• Roof alteration to create the gable wall
• Structural steelwork where required
• Additional floor space
• New windows
• Staircase
• Full insulation upgrade
• Electrics, lighting & heating
• Plastering & decoration

Costs more because: it involves more significant structural change than Velux or dormer conversions.

Mansard £45,000–£70,000

Creates maximum usable space by altering most or all of the roof structure into near-vertical walls — the most extensive and usually highest-cost option.

Best for

• Homes needing maximum extra space
• Large master bedrooms or self-contained areas
• Properties suitable for roof restructuring

Typically included

• Complete roof structure alteration
• Mansard wall construction
• New roof covering
• Windows or French doors
• Structural steelwork
• Staircase
• Full insulation
• Electrics, heating, plastering & finishing

Important: planning permission is often required for mansard conversions.

Room in Roof (Upgrade) £10,000–£20,000

Upgrades an existing, partially converted loft rather than creating a new conversion — improving comfort, safety, insulation and compliance.

Best for

• Existing loft rooms needing improvement
• Cold or poorly insulated spaces
• Properties with outdated electrics or finishes

Typically included

• Insulation upgrades (incl. roof insulation)
• Electrical improvements
• Heating upgrades
• Plastering & decoration
• Flooring improvements
• Building regulation upgrades
• Final compliance checks

Additional Costs to Consider

The main loft conversion price usually covers the core construction work, but additional requirements can increase your overall budget. These costs depend on your property, design choices, structural requirements, and whether extra features are included.

Item	Typical Cost
Ensuite bathroom	£5,000 – £10,000
Dormer window (on dormer conversion)	Varies
Roof windows (Velux)	£1,000 – £2,000 per window
Structural steelwork (if required)	£2,000 – £5,000
Building control fees	£500 – £1,000
Planning permission (if required)	£500 – £1,000
Party wall agreement	£500 – £1,500 per neighbour
Scaffolding	£1,000 – £3,000
Skip hire	£300 – £600

Not every item applies to every project — we set out exactly which extras your conversion needs in your written quotation.

How Much Value Does a Loft Conversion Add to Your Home?

A well-designed loft conversion can increase both the usable space and market appeal of your home. In many cases, adding an extra bedroom, office, or living area can increase property value by around 10–20%, depending on the location, property type, and quality of the conversion.

Property Type	Current Value	Loft Conversion Cost	Approx Added Value	Net Gain
2-bed terrace (Manchester city fringe)	£250,000	£30,000 (dormer)	£25,000-£37,500	£0-£7,500
3-bed semi (Stockport)	£350,000	£35,000 (dormer)	£35,000-£52,500	£0-£17,500
3-bed semi (Oldham)	£280,000	£35,000 (dormer)	£28,000-£42,000	£0-£7,000
4-bed detached (South Manchester)	£550,000	£50,000 (mansard)	£55,000-£82,000	£5,000-£32,000

A loft conversion is an investment in both value and quality of living. Actual return depends on location, demand for extra bedrooms, conversion quality and whether the design meets buyer expectations. Figures are illustrative estimates.

Do You Need Planning Permission for a Loft Conversion?

Most loft conversions do not require planning permission because they are often covered under permitted development rights. However, the rules depend on factors such as the size of the extension, roof design, property type, and whether your home has any planning restrictions.

Permitted development limits for loft conversions:

• Terraced house: up to 40m³ additional volume
• Semi-detached or detached: up to 50m³ additional volume
• No extension beyond the existing roof slope on the front elevation
• No higher than the highest part of the existing roof
• No verandas, balconies or raised platforms

When you DO need planning permission:

• Your property is in a conservation area (e.g. parts of Manchester such as Victoria Park, The Park Estate, Hale Barns)
• Your property is listed
• You exceed permitted development limits
• You want a mansard conversion
• You want a hip-to-gable conversion on certain property types

LAMTANS Engineering can help guide you through planning requirements and building regulations, ensuring your loft conversion is designed and completed to meet UK standards.

Why Choose LAMTANS for Your Loft Conversion?

Choosing the right loft conversion company is essential for achieving a safe, energy-efficient, and regulation-compliant living space. LAMTANS Engineering combines retrofit expertise, project management, and quality standards to deliver professional loft conversion upgrades across the UK.

• Retrofit industry specialists – We focus on energy efficiency, insulation, and compliant upgrades rather than being general builders.
• Experienced project delivery – We have completed numerous energy improvement and property upgrade projects across the UK, supporting homeowners with reliable workmanship.
• 11 industry accreditations – Including TrustMark, PAS2035, ISO9001, and other recognised quality standards.
• Free surveys and quotations – We provide a no-obligation assessment to understand your loft space and project requirements.
• Planning and building control support – We help manage approvals and compliance requirements throughout your conversion.
• Full project management – One dedicated point of contact from initial survey through to completion.

View our loft conversion examples
Read customer testimonials
View our case studies

Frequently Asked Questions

Q: Is £30,000 a reasonable budget for a loft conversion in the UK?
A: Yes. A dormer conversion on a typical 3-bed semi costs £30,000-£35,000. A Velux conversion costs £15,000-£25,000.

Q: How long does a loft conversion take?
A: Velux: 2-3 weeks. Dormer: 4-6 weeks. Hip to gable: 6-8 weeks. Mansard: 8-10 weeks.

Q: Will a loft conversion add value to my home?
A: Yes. A typical loft conversion adds 10-20% to your property value. In most cases, you will not lose money.

Q: Can I convert my loft if I have a low roof?
A: Yes – a dormer or mansard conversion can create headroom even with a low existing roof.

Q: Do I need to move out during the conversion?
A: No. The work is contained in the loft. There will be some disruption (dust, noise, tradespeople moving through the house), but you can live in the rest of your home.

Q: Is LAMTANS RECC and MCS accredited?
A: Yes we are RECC accredited, MCS certified and TrustMark registered. We hold 11 other accreditations.