UK cost guide · September 2026

How much does a loft conversion cost in 2026?

A mid-range loft conversion of about 30 m² costs £32,500 to £42,000 for a rooflight (Velux) conversion and £56,500 to £69,500 for a rear dormer, including VAT. Hip-to-gable conversions cost £66,000 to £81,500 and mansards £78,000 to £102,000. Allow £5,200 to £10,000 for fees, and more in London.

By Estiquote · Prices reviewed 25 September 2026, next review December 2026 · How we calculate

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Loft conversion prices in 2026

Ranges are for a typical home outside London, including VAT, before fees and contingency. Use the calculator for your size, region and finish.

Loft conversion costs by type and finish, UK average outside London, including VAT (September 2026)
Type	Budget	Mid-range	Premium
Rooflight (Velux) (30 m²)	£26,500 to £32,500	£32,500 to £42,000	£42,000 to £54,000
Rear dormer (30 m²)	£48,000 to £56,500	£56,500 to £69,500	£69,500 to £90,000
Hip-to-gable (with rear dormer) (30 m²)	£57,500 to £66,000	£66,000 to £81,500	£81,500 to £102,000
Mansard (30 m²)	£66,000 to £78,000	£78,000 to £102,000	£102,000 to £144,000

Rear dormer loft conversion by size, including VAT
Floor area	Budget	Mid-range	Premium
20 m²	£37,500 to £44,000	£44,000 to £54,500	£54,500 to £70,500
30 m²	£48,000 to £56,500	£56,500 to £69,500	£69,500 to £90,000
40 m²	£57,000 to £67,000	£67,000 to £82,500	£82,500 to £107,000

Loft conversion costs by region

Labour costs vary across the UK far more than materials. London runs about 35% above the UK average and Northern Ireland about 18% below.

Loft conversion costs by region: Rear dormer, 30 m², including VAT
Region	Mid-range cost
UK average (outside London)	£56,500 to £69,500
London	£76,000 to £94,000
South East	£65,000 to £80,000
East of England	£60,500 to £74,500
South West	£58,500 to £72,500
West Midlands	£54,500 to £67,500
East Midlands	£53,500 to £66,000
Scotland	£53,500 to £66,000
North West	£52,500 to £64,500
Yorkshire and the Humber	£52,000 to £64,000
Wales	£51,000 to £62,500
North East	£49,500 to £61,000
Northern Ireland	£46,000 to £57,000

Want it for your area? See local prices and council building control fees for 92 council areas.

Fees and approvals

Design, engineering and approvals come on top of the building work. Building control figures are the middle half of fees charged by the councils we checked in September 2026.

Typical fees and approvals, including VAT where charged
Fee	Typical cost	Notes
Design drawings (planning and building regulations)	£3,600 to £6,000
Structural engineer	£900 to £3,000
Building control (council, full plans)	£750 to £1,000	Middle half of 90 councils in England and Wales for a loft conversion
Lawful development certificate (England)	£270	Optional proof that permitted development applies Optional.
Party wall surveyor (per neighbour)	£1,100 to £1,800	Only if you build on or near a shared wall Optional.

What's included in these prices

Included

Structural floor, steels and any strengthening
Stairs to the new floor
Insulation, plasterboard and fire protection to building regulations
Rooflights or dormer windows
Electrics, heating and decoration to a finished room
Scaffolding and waste removal

Not included

An en-suite bathroom (add a bathroom estimate)
Design, engineering and building control fees (shown separately)
Party wall surveyors
Fitted wardrobes and eaves storage beyond basic
Your contingency

What drives the cost

Type of conversion. Rooflight conversions keep the roof shape and cost least. Dormers add headroom; hip-to-gable and mansard conversions rebuild much of the roof and cost the most.
Headroom. You need enough height at the top of the new stairs and in the room. If the ridge is low, lowering ceilings below or raising the roof adds cost.
Stairs. Where the new staircase lands decides how much of the floor below is disturbed.
Bathroom. An en-suite adds plumbing, drainage and ventilation; budget separately.
Fire safety. A loft room above a two-storey house needs a protected escape route, which can mean fire doors throughout.
Where you live. London lofts cost about 35% more than the UK average; mansards are common there and push prices higher still.

Planning, regulations and VAT

Many loft conversions in England are permitted development if they stay within volume limits (40 m³ for terraced houses, 50 m³ for others) and do not extend the front roof slope. Check the Planning Portal guidance. A lawful development certificate (£274) proves you are within the rules. Every loft conversion needs building regulations approval, and most need a party wall notice.

Checklist: what to ask builders to confirm

Print this or save it as a PDF. Mark each line included, separate or not confirmed as quotes come in. An empty amount means unknown, not free.

Use one column per quote if you are comparing builders
Item	What to confirm	Included? Amount?
Survey and design	Measured survey, headroom check, drawings and structural calculations.
Permissions	Permitted development or planning, building control and party wall notices.
Structure	New floor joists, steels, roof alterations and dormer framing.
Stairs and fire safety	Staircase position, protected escape route and fire doors.
Windows	Rooflights, dormer windows and any escape window.
Services and finishes	Heating, electrics, insulation, plastering and decoration.
Bathroom	En-suite plumbing and drainage, if wanted.

Questions people ask

What is the cheapest type of loft conversion?

A rooflight (Velux) conversion, at about £32,500 to £42,000 including VAT for a mid-range finish, because the roof shape does not change.

How much does a dormer loft conversion cost?

About £56,500 to £69,500 including VAT for a mid-range rear dormer of about 30 m², before fees. Budget and premium finishes run from £48,000 to £90,000.

Does a loft conversion need planning permission?

Often not in England, if it falls within permitted development limits. Building regulations approval is always needed.

How much does a loft conversion cost in London?

About £76,000 to £94,000 for a mid-range rear dormer including VAT, before fees.

Sources and method

Our ranges combine published 2026 UK cost guides, industry data and our own survey of council fees. We check them every quarter. They are planning figures, not quotes: always get at least three detailed written quotes. Read how Estiquote estimates work, or download the full cost data.