Hip to Gable Loft Conversion Cost London 2026: Prices, Planning and What to Expect

A hip to gable loft conversion is one of the most popular types of loft conversion in London, particularly for semi-detached and end-of-terrace houses with a hipped roof. By replacing the sloping hip end of the roof with a vertical gable wall, you create significantly more usable headroom and floor space in your loft. In 2026, a hip to gable loft conversion in London typically costs between £45,000 and £75,000, depending on size, specification and location.

A completed hip to gable loft conversion in London by LCCL Construction

LCCL Construction has completed hundreds of hip to gable loft conversions across London and Hertfordshire. This guide covers everything you need to know about hip to gable costs, what affects the price, planning permission requirements and what to expect during the build.

How Much Does a Hip to Gable Loft Conversion Cost in London in 2026?

The cost of a hip to gable loft conversion in London in 2026 depends on the size of the loft, the specification of materials, whether a rear dormer is included and your location. Below is a breakdown of typical estimated costs:

Standard hip to gable loft conversion: £45,000 to £55,000. This covers a hip to gable structural conversion with a Velux or rooflight in the rear slope, staircase, insulation, plastering, electrics and basic internal finish. Suitable for semi-detached houses with a modest loft space.

Hip to gable with rear dormer: £55,000 to £65,000. The most common combination in London — extending the gable to create a full-width rear dormer significantly increases usable floor area and headroom. This creates a proper bedroom and en-suite with standing room throughout.

High-specification hip to gable with rear dormer: £65,000 to £75,000+. Premium finish including Juliet balcony or roof terrace, high-end bathroom, bespoke joinery and full en-suite. Common in higher-value areas such as Hampstead, Muswell Hill, Highgate and Islington.

What Is a Hip to Gable Loft Conversion?

A hipped roof slopes on all four sides. In a hip to gable conversion, the sloping hip end — typically the side wall of a semi-detached or end-of-terrace house — is replaced with a straight vertical gable wall. This pushes the roof line out to the edge of the property and creates a much larger, more usable loft space.

Hip to gable conversions are almost always combined with a rear dormer loft conversion to maximise the floor space gained. Together, they create one of the largest possible loft spaces achievable within a semi-detached or end-of-terrace house.

What Affects the Cost of a Hip to Gable Loft Conversion in London?

Several factors influence the final cost of your hip to gable loft conversion. Understanding these will help you set a realistic budget.

Whether a rear dormer is included: A hip to gable conversion alone creates more headroom at the sides but limited floor space without a rear dormer. Adding a rear dormer typically adds £12,000 to £18,000 to the cost but makes the difference between a limited storage space and a full habitable bedroom.

Number of rooms created: A single bedroom with en-suite is the most common outcome. Adding a second bedroom, home office or bathroom increases the cost of internal fit-out.

Structural complexity: The hip to gable conversion requires new structural steelwork and roof reconstruction. The complexity depends on the existing roof structure, and older or more unusual roof designs can add cost.

Specification and finish: The quality of windows, bathroom fixtures, flooring, insulation and internal finishes varies widely and can add £5,000 to £15,000 to the overall cost depending on the level of specification chosen.

Location in London: Labour and material costs are higher in inner London boroughs than outer North London areas. LCCL Construction operates across all areas and provides detailed cost estimates wherever you are located.

Do You Need Planning Permission for a Hip to Gable Loft Conversion in London?

Most hip to gable loft conversions can be carried out under permitted development rights, meaning no full planning permission application is required. However, you will need to meet specific size and design criteria. The enlarged part of the roof must not exceed the highest point of the existing roof, and the materials used must be similar in appearance to the existing house.

Planning permission will always be required if the property is in a conservation area, is a listed building, or if the conversion exceeds permitted development limits. LCCL Construction assesses planning requirements for every project as part of our free initial consultation.

How Long Does a Hip to Gable Loft Conversion Take?

A hip to gable loft conversion typically takes 10 to 14 weeks to build from the day work starts on site. The full project timeline from initial consultation to completion is usually 5 to 8 months, which includes the design stage (4 to 6 weeks), permitted development confirmation or planning permission if required (4 to 12 weeks), building regulations approval (2 to 4 weeks), party wall agreements (2 to 8 weeks) and the construction phase.

At LCCL Construction, we manage all pre-construction stages simultaneously where possible to reduce the overall timeline. You will have a dedicated project manager throughout keeping you informed at every stage.

Is a Hip to Gable Loft Conversion Worth the Cost?

Yes — a hip to gable loft conversion is one of the most effective ways to add space and value to a semi-detached or end-of-terrace house in London. A well-executed conversion with a rear dormer typically adds between £50,000 and £100,000 to the value of a London property, which in most cases exceeds the cost of the project.

The practical benefit is equally significant — a hip to gable conversion with rear dormer creates a full master bedroom suite with en-suite bathroom, transforming a previously unusable loft into the most desirable room in the house. For more detail on the return on investment, see our guide on how much value a loft conversion adds to a London property.

Hip to Gable vs Other Loft Conversion Types

Hip to gable is the right choice if your property has a hipped roof — a dormer loft conversion alone won't create enough space in a hipped property. For terraced houses with a gable end already in place, a dormer or L-shaped loft conversion may be more appropriate. LCCL Construction will assess your roof type and recommend the most suitable conversion during a free site visit.

Why Choose LCCL Construction for Your Hip to Gable Loft Conversion?

LCCL Construction is a specialist loft conversion company in London based in Finchley, North London with over 20 years of experience. We have completed hundreds of hip to gable loft conversions and have over 200 verified reviews at 4.7 out of 5. We are LABC Award Winners 2024 for Best Residential Project and members of the National Federation of Builders.

As a design and build company, we handle everything from architectural drawings and planning through to structural engineering, building regulations, party wall agreements and construction. One company responsible for every stage.

We provide detailed cost estimates before any work begins so you have full clarity on budget from the start. There are no hidden extras — the estimate we provide reflects the full scope of work.

To get a free consultation and detailed cost estimate for your hip to gable loft conversion, call LCCL Construction on 020 8037 7332 or book online to arrange a site visit.