How much does a loft conversion cost in the UK?

A loft conversion in the UK typically costs around £27,500 to £65,000+, depending on the type of conversion, the size of the loft, and how much structural work is needed. Recent UK guides put a simple rooflight/Velux-style conversion at the lower end, with dormer, hip-to-gable, and mansard conversions costing much more.

For many homeowners, a realistic planning figure is around £50,000 for a typical full loft conversion, but some projects will land below or well above that. The final cost depends on the conversion style, stairs, insulation, structure, finishes, and whether planning or extra professional fees are needed.

Typical loft conversion cost in the UK

Rooflight / Velux loft conversion: around £22,500–£30,000
Dormer loft conversion: around £40,000–£60,000
Hip-to-gable loft conversion: around £50,000–£70,000
Mansard loft conversion: around £50,000–£80,000
Typical overall average: around £50,000 for many full loft conversion projects

Cost breakdown

A loft conversion quote may include some or all of the following:

structural work to the roof and floor
insulation and plastering
windows or dormers
stairs to the new room
electrics and lighting
plumbing, if a bathroom is included
flooring and decorating
design, planning, and approval costs in some cases

As rough current examples:

Rooflight conversion: around £27,500
Dormer conversion: around £50,000
Hip-to-gable conversion: around £60,000
Mansard conversion: around £65,000

What affects the price?

Several things can push the cost up or down:

Type of conversion — rooflight conversions are usually cheapest, while mansard and hip-to-gable projects are more expensive.
Size of the loft — larger spaces usually cost more to convert.
Structural complexity — major roof alterations increase labour and materials.
Staircase design — loft stairs can add a meaningful extra cost, with current guidance putting them around £1,800 to £6,000 depending on design and materials.
Planning and approvals — building control and related approvals can add several hundred pounds. Homebuilding currently notes building control approval fees in the region of £300 to £900.
Finishes and fittings — bathrooms, bespoke joinery, premium windows, and better finishes all increase the total.

What’s usually included?

A standard loft conversion quote may include:

structural floor strengthening
insulation
roof alterations
windows or dormer installation
plastering
staircase installation
basic electrics
basic interior finishing

It does not always include:

decorating
flooring upgrades
fitted wardrobes
bathroom installation
architect fees
party wall costs
planning application or lawful development paperwork

What is the cheapest type of loft conversion?

Usually, a rooflight or Velux-style loft conversion is the cheapest because it uses more of the existing roof structure and involves fewer external changes. Current UK cost guides place these at roughly £22,500 to £30,000.

What is the most expensive type of loft conversion?

A mansard loft conversion is often one of the most expensive because it involves major roof alteration and creates the most usable space. Current UK pricing guides place mansards at roughly £50,000 to £80,000 or more.

Is a loft conversion worth it?

Often, yes. A loft conversion can create valuable extra living space without extending outward, and Homebuilding notes that a well-executed loft conversion can add up to 25% to a home’s value. That will vary by property, area, and finish, but it is one of the big reasons loft conversions remain popular.

Frequently asked questions

How much does a loft conversion cost in the UK on average?

A realistic modern average is often around £50,000, though simple projects can be much lower and more complex ones much higher.

Can a loft conversion cost less than £30,000?

Yes, some simple rooflight conversions can come in around that level, but many full loft conversions now cost more.

Do stairs add much to the cost?

They can. Current guidance puts loft stairs at roughly £1,800 to £6,000, depending on the design.

Do I need building regulations approval?

Yes, loft conversions generally require building regulations approval, and Homebuilding notes fees often in the £300 to £900 range.

Related guides

“See full Home Costs guide”

Final note

For a useful rule of thumb, £50,000 is a sensible modern planning figure for a typical UK loft conversion, but your actual quote will depend heavily on the type of conversion, structural complexity, and the level of finish you choose.