Attic Conversion Cost in the UK: A Pricing Guide

Estimated reading time: 6–7 minutes

Quick Cost Overview for Attic Conversions

Whether you're in the early stages of planning or comparing quotes, here's a snapshot of what to expect:

• A standard attic conversion costs between £20,000 and £80,000.
• A Velux conversion, the most affordable option, starts from around £20,000.
• Premium Mansard conversions can reach up to £85,000 for larger properties.
• A well-executed attic conversion can add 10-20% to your home's value.

A Guide to Attic Conversion Costs

Attic conversion costs vary widely depending on the type of conversion, your property, and where you are in the UK.

This guide breaks down everything you need to budget for — from the conversion itself and structural work through to planning permission and the finishing touches.

In this price guide, we'll cover:

1. Why Invest in an Attic Conversion?
2. What Does an Attic Conversion Cost?
3. Different Attic Conversion Types and Costs
4. Planning Permission Costs for Attic Conversions
5. Cost-Saving Tips for an Attic Conversion
6. Find an Attic Conversion Company with MyBuilder
7. FAQ: Common Questions about Attic Conversion Costs

Read on to find out everything you need to know before starting your attic conversion.

Why Invest in an Attic Conversion?

An attic conversion transforms underused roof space into a practical, valuable room, whether that's a new bedroom, a home office, or a dedicated space for the kids. For many homeowners, the appeal isn't just about square footage; it's about getting more from the home they already own.

Here are a few key reasons homeowners choose an attic conversion:

• Extra living space: An attic conversion turns dead space into bedrooms, offices, or playrooms without the disruption or cost of a full extension.
• Cost-effective expansion: Attic conversions are often cheaper per square metre than side or rear extensions, with shorter build times.
• Energy efficiency: Modern insulation and ventilation installed as part of a conversion can reduce heat loss and cut heating bills year-round.

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What Does an Attic Conversion Cost?

Having an attic conversion completed by a professional company typically costs between £20,000 and £80,000. The final figure depends on the conversion style, the size of the space, any structural requirements, and your location in the UK.

• Project time: A standard attic conversion takes 6 to 12 weeks. Simpler Velux jobs can be completed in 4 to 6 weeks, while dormer conversions involving planning permission may stretch to 14 weeks or more.

• What's included: The average cost of an attic conversion in the UK generally covers an initial survey, structural reinforcements, design, building regulations approval, and the fit-out of the new space.

Basic Velux conversions start from around £20,000 to £45,000, as they work within the existing roofline without major structural changes. Dormer conversions, which extend the roof to create full headroom, typically cost £35,000 to £65,000 due to the additional engineering and materials involved.

It's always worth discussing your options with a professional before committing to a specific conversion type - what works for one property may not suit another.

Post your job on MyBuilder and local attic conversion companies can respond with their advice and quotes.

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Different Attic Conversion Types and Costs

There are several attic conversion styles to choose from, and the right one depends on your budget, your roof structure, and how much usable space you need. Here's a breakdown of the main options and their typical costs.

Cost breakdown of different attic conversion types:

Conversion Type	Average Cost (30m²)
Velux (rooflights)	£20,000 – £45,000
Rear Dormer	£35,000 – £65,000
Hip-to-Gable	£40,000 – £70,000
Mansard	£55,000 – £85,000

Velux Attic Conversion Costs

This is the most affordable approach, adding skylights to your existing roofline without any structural changes to the roof pitch. A Velux conversion works best for attics with reasonable headroom already, keeping average attic conversion costs in the UK to around £20,000 to £45,000. It's the quickest option to deliver and typically falls under Permitted Development, avoiding planning fees.

Rear Dormer Attic Conversion Costs

A rear dormer extends the back of the roof to create full headroom and usable floor space, making it a popular choice for terraced houses across UK cities. The additional engineering, materials, and frequent need for planning permission push rear dormer costs to £35,000 to £65,000. The payoff is a significantly larger, more functional room.

Hip-to-Gable Attic Conversion Costs

A hip-to-gable conversion replaces the sloped end of your roof with a vertical gable wall, giving you considerably more width and floor area. It suits end-of-terrace and semi-detached properties well, and at £40,000 to £70,000, delivers a substantial increase in usable space without the visual impact of a full mansard.

Mansard Attic Conversion Costs

A mansard conversion is the premium option, raising and reshaping the roof to provide full headroom across the entire space - ideal for multi-room layouts or a self-contained flat. Costs typically run from £55,000 to £85,000, and most will require full planning permission. Despite the higher upfront investment, a mansard conversion delivers the greatest increase in floor area and tends to add significant resale value. Read more on mansard loft conversion costs.

Planning Permission Costs for Attic Conversions

Most straightforward attic conversions fall under Permitted Development, meaning you won't need full planning permission, provided the work stays within certain limits. However, larger projects, listed buildings, and properties in conservation areas are a different matter.

When you will likely need planning permission:

• The conversion adds more than 40m³ of additional roof space (50m³ for detached houses).
• The work involves a front-facing dormer or alters the overall shape of the roof significantly.
• Your property is in a conservation area, a National Park, or is a listed building.
• The new roof structure exceeds the height of the existing roof ridge.

Full planning permission typically costs £206 in England (the application fee), though design drawings, surveys, and potential resubmissions can push the total planning-related spend to £1,000 to £3,000 or more.

A professional attic conversion company can check your property's specifics and manage the planning process on your behalf, reducing the risk of costly rejections. You can find out more in our guide to loft planning permission costs.

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Cost-Saving Tips for an Attic Conversion

An attic conversion is a significant investment, but there are practical ways to manage costs without cutting corners on quality.

• Choose a simpler conversion type: A Velux conversion at £20,000 to £45,000 is the most affordable route and still delivers a fully functional room. Only upgrade to a dormer or mansard if your headroom genuinely requires it.
• Stay within Permitted Development: If your project qualifies, typically under 40m³ added volume, rear or side facing only, you avoid full planning fees and the time delays they bring.
• Compare multiple quotes: Post your job on MyBuilder and request estimates from several loft conversion companies to ensure you're paying a fair rate for labour, materials, and design.
• Time the work strategically: Booking for quieter months, January through March, or late autumn, can result in lower labour costs as demand drops and availability increases.
• Bundle the trades: If you're also planning electrical work or insulation upgrades, combining them with your conversion can reduce overall costs compared to bringing trades in separately.

Find an Attic Conversion Company with MyBuilder

Finding the right attic conversion company doesn't have to mean hours of research. Post your job on MyBuilder and local, available professionals can respond with their advice, services, and quotes. You can browse their profiles, read customer reviews from previous jobs, and compare options before deciding who to contact.

All tradespeople on MyBuilder undergo checks at registration - such as ID documents, company details, certifications for regulated jobs and skill assessments - allowing you to hire with confidence.

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FAQ: Common Questions about Attic Conversion Costs

What Is the Cheapest Way to Do an Attic Conversion?

A Velux conversion is the most affordable option, typically costing £20,000 to £45,000. Keeping the project within Permitted Development limits avoids planning fees, and opting for standard finishes over bespoke joinery will keep material costs down. Booking during quieter periods, January or late autumn, can also reduce labour rates by 10 to 20%.

Does an Attic Conversion Increase Your Council Tax?

It can. Adding a habitable room increases your property's assessed value, which may push it into a higher council tax band. The increase is typically £200 to £500 per year, though this varies by local authority and how significantly the conversion changes your home's value. Your local council can advise before work begins.

How Long Does an Attic Conversion Take?

Most attic conversions take between 6 and 12 weeks from start to finish. A Velux conversion can be completed in 4 to 6 weeks, while a dormer or mansard involving planning permission may take 14 weeks or more. It's worth building in extra time for potential delays from weather, material supply, or planning decisions.

Will an Attic Conversion Add Value to My Home?

Yes, in most cases. An attic conversion typically adds 10 to 20% to a property's market value, roughly £20,000 to £65,000 for the average UK home. Adding a bedroom or home office is particularly valued by buyers, especially in areas where moving to a larger property is expensive. You can browse photos of completed attic conversion projects on MyBuilder to get a sense of what's achievable and the standard of work from local companies.

Can I DIY Parts of an Attic Conversion?

Structural elements, joists, steel beams, electrical installations, and anything requiring Building Regulations sign-off, must be carried out by qualified professionals. These aren't areas where cutting costs is worth the risk. That said, non-structural finishing work such as painting walls, laying carpet, or fitting furniture could be tackled yourself, potentially saving £1,000 to £2,000 on the final bill.