The ConstructionLtd

London's Construction Experts

The ConstructionLtd
Loft Conversions

Loft Conversions London — Dormer, Hip-to-Gable & Mansard

A loft conversion is the most cost-effective way to add a bedroom and bathroom to a London home. By converting unused roof space into habitable rooms, you gain valuable living area without sacrificing garden space or extending your property's footprint. In a city where every square metre counts, that efficiency makes loft conversions London's most popular home improvement project. We have completed over 100 loft conversions across London — from simple dormer conversions on Victorian terraces to complex mansard builds in conservation areas.

Starting From£25,000
Get Free Quote

Types of Loft Conversions

Rear Dormer

The most common loft conversion type in London. A flat-roofed rear dormer extends from the existing roof slope, creating full standing headroom across most of the loft floor area. Ideal for Victorian and Edwardian terraces where the existing roof pitch provides good height at the ridge.

Typical cost:£42,000–£60,000

Hip-to-Gable

Designed for semi-detached and detached houses with hipped roofs. The sloping hip end is rebuilt as a vertical gable wall, significantly increasing usable floor area. Often combined with a rear dormer for maximum space.

Typical cost:£50,000–£75,000

Mansard

A mansard conversion replaces the existing roof structure with steeply angled walls and a flat or nearly flat roof, maximising internal volume. Common in London's terraced properties and often required in conservation areas. The most expensive but most spacious option.

Typical cost:£55,000–£85,000

Velux/Rooflight

The simplest and most affordable option — rooflights are installed into the existing roof slope without altering the external structure. Suitable only where existing headroom is already adequate (typically detached houses with steep roof pitches).

Typical cost:£25,000–£40,000

L-Shaped Dormer

Combines a rear dormer with a side dormer (over the existing rear addition's roof) to create a large L-shaped floor plan. Common on Victorian terraces with two-storey rear additions. Creates enough space for a bedroom, en-suite, and sometimes a small study area.

Typical cost:£50,000–£70,000

Loft Conversions Costs & Pricing

TypeSizePrice Range
Velux/Rooflight4–5 weeks£25,000–£40,000
Rear Dormer6–8 weeks£42,000–£60,000
L-Shaped Dormer7–9 weeks£50,000–£70,000
Hip-to-Gable + Dormer8–10 weeks£50,000–£75,000
Mansard10–12 weeks£55,000–£85,000

* Prices are indicative for London construction in 2026. Final price depends on specification, finish, and site-specific factors. All our projects are delivered on a fixed-price contract.

Frequently Asked Questions

Do I need planning permission for a loft conversion in London?
Most dormer and hip-to-gable loft conversions fall under permitted development — no planning application needed — provided they comply with size limits (50 cubic metres for detached/semi-detached, 40 for terraced), height restrictions, and setback rules. Properties in conservation areas usually require full planning permission.
Will a loft conversion add value to my property?
Loft conversions are one of the highest-return home improvements. Adding a bedroom and bathroom to a London property typically increases value by £80,000–£200,000+ depending on location — significantly more than the cost of the conversion.
How disruptive is a loft conversion?
Less disruptive than most people expect. The heavy structural work — steels, floor reinforcement, and dormer construction — is completed within the first 7–10 days. After that, most work is internal. We maintain weather protection during the roof opening phase and keep dust and noise to a minimum throughout.
Can you convert any loft?
Most London lofts can be converted, but suitability depends on existing head height (minimum 2.2m at the ridge is ideal), roof structure type, and Building Regulations compliance. We assess your loft during a free survey and advise on the best conversion type for your property.
What about staircase access?
Building Regulations require a fixed staircase to the loft (not a ladder). We typically position the new staircase above the existing stairs, using space from a landing or a box room. In some cases, we can design the staircase to minimise impact on existing rooms.

Get a Quote for Your Loft Conversion Project

Tell us about your property and what you're planning. We'll respond within 48 hours with a preliminary estimate and arrange a free site visit.

Free site visit and assessment
Fixed-price quote — no surprises
In-house planning and design team
Dedicated project manager throughout

Loft Conversions Quote

Free consultation within 48 hours.

Or call us now: 07438 319930

Other Services

From £30,000Home ExtensionsFrom £10,000Kitchen RenovationsFrom £8,000Bathroom RenovationsFrom £40,000Full Property Renovations
Get Started Today

Start Your Loft Conversion Project

Get a free, no-obligation quote within 48 hours. We cover every London borough and the Home Counties.

Get Free Quote07438 319930

Free consultation • Fixed-price contract • No obligation