This article is London-specific because homeowners here typically pay more than the UK national average costs for a loft conversion, due to higher labour costs, scaffolding challenges, and London borough regulations.
We’ve included common unexpected costs to projects at the bottom of this article, so make sure you check them too.
Table of Contents
This sort of loft conversion is the simplest and most affordable option. The roof structure remains unchanged; you add roof windows (Velux or similar) and insulate the loft space – which doesn’t necessarily add standing room to your square footage.
Best for:
Terraced houses with adequate head height
Homeowners on a tighter budget
Projects where minimal external change is desired
What’s included:
Roof windows (usually 2–4)
Insulation to building regulations
Flooring and staircase
Basic electrical work (lighting, sockets)
Plastering and decoration
What’s NOT included:
Major structural changes
Dormer extensions
Bathroom/ensuite
Typical timeline: 6-8 weeks
Approximate cost: £38-45,000
One of the most popular types of loft conversion, this is a box-like structure that extends vertically from the slope of the roof, creating additional headroom and floor space.
Best for:
Terraced and semi-detached houses
Creating full bedroom + ensuite space
Maximising usable space in London properties
What’s included:
Full dormer construction (front, sides, roof)
Increased headroom and floor space
Insulation, flooring, staircase
Electrical work, plumbing (if bathroom included)
Plastering, windows, doors
What’s NOT included:
High-end finishes
Party Wall Agreement costs
Typical timeline: 10-12 weeks
Typical cost: £48-55,000
This type of loft conversion is when the sloping “hip” side of the roof is extended vertically to create a gable end, significantly increasing internal space.
Best for:
Semi-detached and detached houses
Properties where maximum space is needed
London suburban homes (e.g., Blackheath, Wandsworth)
What’s included:
Structural changes to roof shape
Gable wall construction
Increased floor space (up to 50% more than Velux)
Insulation, flooring, staircase, windows
Electrical and plumbing work
Typical timeline: 9-12 weeks
Typical cost: £55-65,000
This is two dormers joined at right angles, creating an L-shaped footprint. This type of loft conversion is also popular in London as it’s a particularly good option on Victorian terraced houses.
Best for:
Victorian terraced houses
Creating two bedrooms or a bedroom + office
Properties with rear extensions
What’s included:
Two dormer structures
Maximum space utilisation
Full finishing (flooring, plastering, electrical)
Optional bathroom/ensuite
Typical timeline: 10-14 weeks
Typical cost: £55-65,000
This type of loft conversion is a near-vertical extension to the roof, and so almost always requires planning permission. It looks more like a full additional storey when viewed from the road. It
Best for:
Terraced houses where maximum space is needed
Properties not in conservation areas
Homeowners wanting near-full additional floor
What’s included:
Full roof reconstruction on one or both sides
Maximum headroom and floor space
High-quality windows and finishes
Full bathroom/ensuite options
Important: Almost always requires planning permission
Typical timeline: 10-14 weeks
Typical cost: £57,000+
Our quotes are free and fully transparent, so you will never be caught unawares by and of these elements mentioned below. We fully expect you to get quotes from other companies – so make sure you’re holding them to the same high standards in terms of their quote detailing!
| Party Wall Agreement | £1,000 – £2,000 | If you share a wall with neighbours (common in terraced London houses) |
| Building Regulations Approval | £800 – £1,500 | Required for all conversions |
| Lawful Development Certificate | £300 – £500 | Recommended even if permitted development (proves compliance) |
| Architectural Plans | £1,500 – £3,000 | For more complex conversions |
| Scaffolding | £2,000 – £4,000 | This should specifically be included in quoted price, so verify if you don’t see it itemised. |
| Heat Pump / Solar Panels | £5,000 – £15,000 | If adding eco-features |
| Bathroom / Ensuite | £5,000 – £8,000 | If not included in base price |
| High-end Finishes Upgrade | £5,000 – £15,000 | Premium flooring, fixtures, smart home tech |
Property Type: Terraced, Semi-detached, and Detached will affect complexity and your project size.
Conversion Type
Size of Loft: Please note, a minimum head height of 2.2–2.4m is required
Finishes Level: Standard included, Premium +10–20%, Bespoke/Luxury +20–40%
Bathroom Addition
Conservation Area
Need for Party Wall Agreement
Central London (Camden, Westminster, Kensington)
Conservation areas are common, and we find that there’s higher labour costs if we need to supplement our team.
South London (Blackheath, Wandsworth, Clapham, Streatham)
These areas have more moderate restrictions, and we find that there’s good contractor availability for when we need to supplement our core team of experts.
East London (Hackney, Tower Hamlets, Stratford)
These areas have more Victorian terraces and we know there’s a fair few competitors in the area. We’re happy to price match to the best of our abilities, provided their quotes are as transparent as ours!
West London (Hammersmith, Chiswick)
These spots have higher property values, and unsurprisingly there are a lot of niche premium contractors if you want something like complex tiling with handmade ceramics.
North London (Islington, Hackney borders)
Conservation areas are very common, and there’s also good contractor availability here.
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If you’re ready to sit back and enjoy a Simply Easy Refurb on your home, contact us today.
