Loft Conversion Costs

Loft Conversion Costs Table

Loft conversions are one of the cheapest ways to expand the usable space of your home.

Most homes will already have a loft area, but one that is non-functional or only used for storage. In these cases, there’s not much point in making a house extension London outwards as it’s much more cost effective to simply convert this into liveable space.

The table below shows estimated prices for loft conversion projects in London.

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Cost of Loft Conversions in London

The cost of a loft conversion is usually around £1000/sqm.

Site survey: from £400
Planning: from £950
Construction from £40K
Cost/m² about £1000m²

Site Survey

We conduct a full site survey with accurate measurements and photographs, enabling us to prepare scaled drawings for planning applications and documentation for your proposal.

Site Survey: from £400


We assess the history/context of the site and surroundings, research the local planning authority and establish previously proposed planning applications, either accepted or refused.

Planning: from £950


We offer a wide range of project development and management services during the construction phase, including project and development management.

Construction from £40K
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Different Loft Conversion Type Costs

Loft Conversion Type Image Cost
Storage Only From £2000
Velux Conversions diagram of velux conversion for blog on cost of loft conversions Average Total Cost: £13,000 – £27,000
Per Square Metre: £1,000 – £1,300+VAT per m2
Dormer Conversions diagram of dormer types for blog on cost of loft conversions Average Total Cost (UK): £23,000 – £37,000
Average Total Cost (London): £28,000 – £52,000
Per Square Metre: £1,100 – £1,400+VAT per m2
Hip to Gable Conversions diagram of hip to gable roof for blog on cost of loft conversions Average Total Cost: £28,000 – £37,000
Mansard Roof Conversions diagram of mansard roof for blog on cost of loft conversions From ££43,000

What Factors Affect the Cost of Your Loft Conversion?

  • What your loft is like now
  • The intended use after completion
  • Type of conversion
  • The professionals you choose to hire
  • The residential area where your home is located

Other Factors

  • Storage: Your costs will be low if you are simply looking to gain storage space. For living spaces the costs will be significantly higher, especially if you are having an additional bathroom.
  • Living: For living spaces the costs will be significantly higher, especially if you are having an additional bathroom.
  • Shell: This is the basic structure and reinforcements in your new roof space.
  • First fix: This is when you add wiring, pipes and plaster.
  • Second fix: Including your power points, sanitary ware and doors.
  • Third fix: Would be things such as protection devices, e.g. earthing conductors.
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Standard Loft Conversion Construction Costs

Why do Loft Conversions Work Out Cheaper than Other Extensions?

Relaxed Planning Permissions

Building upwards is a popular trend in British home improvement projects across the country. Planning laws have been relaxed due to the shortage of housing stock for family-sized homes, this in turn has created more precedents for new applications and perpetuates the case for loft conversions.

Good Value / Investment ratio

Converting your loft adds about 15-20% to your property value, even though the build cost is less than this. This is an attractive investment for any future plans to move abroad or to a retirement home. Some people know they will never move, but most do not have such cast-iron plans set in stone. Even for couples who don’t move, lofts still make financial sense because any legacy to their children will be more valuable than in its current (un-extended) condition.

Construction Type Price*
First fix estimate £20,000 – £30,000
Second fix estimate £10,000 – £25,000
Third fix estimate £5,000 – £9,000
Staircase to loft £600 – £1,000
Spiral stairs £800 – £1,800
Dormer window structure with glazing £3,500 – £6,500

[*All prices are UK averages for builders.]