Loft Conversion London | Design, Build, Fixed Prices

The Beams team removed all the stress and matched me with a wonderful contractor."

Teresa

Queen's Park

On time and on budget. A real pleasure."

Eleanor

Stoke Newington

Completed our renovation project within budget and on time."

Evelyn

Bow East

London's loft conversion experts

Most loft conversion companies give you one quote from one builder and ask you to trust them. Beams works differently - we match you with vetted specialists, give you up to three like-for-like quotes to compare, and put proper protections in place before work begins.

Vetted builders, not one-size-fits-all

Every builder in the Beams network is personally vetted — visited in person, references checked, recent work inspected. You meet up to three before committing.

Fixed-price contracts

Your builder quotes a fixed price before work begins — agreed in writing, with milestone payments held securely until you approve each stage. No surprises mid-build.

Design support available

Visualise your new space in 3D before work begins. Your first design call is free.

Types of loft conversion

Velux / rooflight — simplest and most affordable. No structural changes, Velux windows installed into the existing slope.

Dormer — most popular in London terraces. Adds full-height usable space, typically enough for a bedroom and en suite.

L-shaped dormer — ideal for Victorian terraces with back additions. Can add two bedrooms and a bathroom.

Hip-to-gable — suited to semi-detached and end-of-terrace homes with hipped roofs. Often combined with a rear dormer.

Mansard — maximum space. Near-vertical walls and a flat roof. Almost always requires planning permission.

Most London lofts can be converted

The key factors are head height (ideally 2.2m+ from floor joist to ridge), roof structure and pitch. If your water tank is in the loft, it will need relocating — your builder factors this in.

Not sure about your loft? A free estimate conversation is the quickest way to find out.

Loft conversion costs in London

Loft conversion costs in London typically run higher than the national average — due to labour rates, access constraints and the complexity of working in densely built Victorian and Edwardian streets.

As a guide:

Velux: £25,000–£45,000
Dormer: £45,000–£75,000
Hip-to-gable: £55,000–£75,000
Mansard: £70,000–£100,000+

All figures exclude VAT and professional fees. For a full breakdown, see our guide below.

Planning permission for loft conversions

Most loft conversions in London fall under Permitted Development rights — no planning permission needed. Exceptions include flats, conservation areas, listed buildings and mansard conversions. Building Regulations approval is always required, and the Party Wall Act applies if structural work affects a shared wall.

For more information, see our guide below.

How a Beams loft conversion works

A clear process from first conversation to finished space.

Step 1 — Get your estimate
Tell us about your home and what you're hoping to create. Your planner gives you an estimate range before any commitment.

Step 2 — Design and plan
Work with a Beams designer to visualise the space in 3D — or work directly with your builder. Your first design call is free.

Step 3 — Built by your vetted builder
Your matched builder runs the project day to day — structure to finishing — under a fixed-price contract. Milestone payments held securely until you approve each stage. 12-month workmanship warranty included.

Why a loft conversion beats moving house

A well-executed loft conversion in London typically adds 15–25% to your property's value — often significantly more where an additional bedroom and en suite are created.

Compare that to moving: stamp duty alone on a £750,000 London property is £27,500, and total moving costs regularly exceed £40,000 — before you've found somewhere bigger to buy.

Loft conversions across London

We work with vetted builders across all London postcodes — North London, South London, East London and West London. Whether you're in a Victorian terrace or a semi-detached Edwardian, our builders know the properties, the planning rules and the borough-specific quirks that come with converting a London loft.

Loft conversions in London