How Much Does a Loft Conversion Cost in the UK?

Scott Marsden
Aug 1
2 min read

A loft conversion is one of the most popular ways to add space and value to your home - without the hassle of moving. But how much does a loft conversion actually cost in the UK, and what should you budget for?

In this blog, we break down the typical costs, the key factors that influence pricing, and what you can expect from your investment.

Average Loft Conversion Costs (2025)

The cost of a loft conversion varies depending on the type of conversion, the size and structure of your property, and the level of finish you’re after. Here's a guide to the most common types:

Type of Loft Conversion	Typical Cost (incl. VAT)
Basic Room in Roof	£20,000 – £30,000
Dormer Conversion	£30,000 – £50,000
Hip-to-Gable Conversion	£40,000 – £60,000
Mansard Conversion	£50,000 – £70,000+
Luxury/Bespoke Fit-Out	£60,000 – £100,000+

What Affects the Cost of a Loft Conversion?

Several factors will influence your final cost. These include:

Size and complexity: Larger spaces or conversions requiring structural steelwork cost more.
Type of property: Terraced, semi-detached and detached homes may have different structural needs.
Planning and permissions: Most loft conversions fall under Permitted Development, but some-like mansard or hip-to-gable-may require full planning permission.
Staircase design: Creating access to your new space often involves significant alteration.
Plumbing and electrics: Adding a bathroom or lighting will increase the budget.
Location: Costs in London and the South East are typically 10–20% higher.

What’s Included in a Loft Conversion?

A standard conversion should include:

Structural strengthening and insulation
Flooring, plastering, and decorating
New staircase
Velux or dormer windows
Electrical and lighting installation
Heating connections or radiators
Optional ensuite bathroom (at additional cost)

At Klyra, we help homeowners and builders plan, budget, and manage projects like this with confidence. Whether you're managing your own loft conversion or working with a contractor, our remote consultancy service ensures every box is ticked - from feasibility to compliance.

Will a Loft Conversion Add Value?

Yes - a well-designed loft conversion can increase your home’s value by up to 20%, according to multiple property reports. It's a smart way to gain an extra bedroom, office, or living space, especially in high-demand urban areas.

Should You DIY, Hire a Builder, or Use a Project Manager?

Each option has pros and cons:

DIY or homeowner-led: Cost-effective but requires strong planning and knowledge.
Builder-led: Convenient but you may lack full control over costs and decisions.
Guardian Angel (Klyra service): You stay in control, but we guide you through the process step-by-step, ensuring compliance, quality, and value.

Thinking about a loft conversion? Let Klyra be your construction sidekick. Our virtual consultancy gives you clarity, structure, and confidence - whether you’re hiring a builder or managing it yourself.