More than the room at the top of the stairs

Roof in New Malden at the membrane and batten stage before tiling — New Malden roof at membrane and batten stage. Our director’s previous project-management experience, before Vayton.

Roof structure and weatherproofing

The package may include specified structural supports, new floor construction, roof alterations, dormer construction, insulation, rooflights and windows. Roofing junctions and temporary weather protection need planning into the sequence.

Do not assume the existing ceiling joists form a suitable floor for a new habitable room. The structural information has to show how the additional loads are carried through the building.

Timber staircase and landing during interior fitting — Timber stair and landing during fitting, from our director’s project experience.

Stairs, rooms and finishes

The position of the staircase affects both the loft and the floor below. Agree room access, storage, bathroom layout where required, doors, heating, electrical work and the intended finishes.

Include making good along the stair route and in any affected rooms below. These areas are easy to miss when comparing a quotation focused only on the roof space.

Rooflight, dormer, hip-to-gable or mansard?

The conversion type changes how the roof space is formed. Compare the options against a measured design, the stair position and the permissions that apply to your property.

Rear slope of a Victorian terraced house with three flush rooflights in a slate roof — Illustration: rooflights in the rear slope of a Victorian terrace. The roof shape stays the same.

Rooflight conversion

This adds roof windows while largely keeping the existing roof shape. The existing roof geometry still determines the available headroom and room layout.

Dormer loft conversion

This adds a projecting roof structure with a more upright wall and window arrangement. Its position and dimensions influence floor use, daylight and the external appearance.

Read the dormer loft conversion guide

Pair of 1930s semi-detached houses, one with a hip-to-gable loft conversion and one with its original hipped roof — Illustration: the left-hand semi has a hip-to-gable conversion; the right-hand semi keeps its original hipped roof.

Hip-to-gable conversion

This changes a sloping hip end to a gable as part of the proposed roof design. Suitability depends on the house, the structure and the permitted scheme.

Rear mansard roof with a steep slate slope and two lead dormers on a Victorian terrace — Illustration: a rear mansard with a steep slate slope, lead dormers and raised party walls.

Mansard conversion

A mansard reshapes the roof with a steep lower slope and a shallower upper section. On a London terrace, the design has to consider neighbouring rooflines, party walls, window positions and how the stair arrives in the new room. Establish the planning route and structural design before agreeing the construction package.

For a loft bedroom with an ensuite, put water and waste plumbing and lighting and power in the same brief as the structure and stairs.

Check feasibility before choosing the finishes

Useful space is what is left after the completed floor, insulation and ceiling build-up, which is less than the empty roof height. A measured design should look at headroom, stair geometry, escape arrangements, ventilation and the way daylight reaches the room.

Building regulations approval is required to convert a loft into habitable space. Planning permission may also be needed, depending on the scheme and property. Agree who supplies design information, handles applications and inspections, and advises on any party-wall requirements.

What changes the cost of a loft conversion?

Two houses with similar roof areas can need very different structures and access arrangements. Compare the complete scheme and the work to the existing home.

For typical London price ranges by loft type, plus the fees and VAT to budget separately, see loft conversion cost in London.

For broad UK context, typical starting prices are £30,000 for a rooflight conversion, £50,000 for a dormer, £60,000 for a hip-to-gable conversion and £70,000 for a mansard, checked on 28 October 2026. They are not Vayton prices or London quotations.

Use the figures to understand the scale of the project, then price your actual design. Confirm the tax basis and whether stairs, structural work, bathroom fitting, finishes, professional fees and approvals are included. A shell-only package needs a separate allowance for the work left to complete.

Compare shell loft conversion inclusions

Quotation item	What to make clear
Conversion form	Rooflight, dormer or other roof alterations, structural supports and access for materials.
Staircase and circulation	New stairs, openings, doors, fire-safety details and making good below the loft.
Bathrooms and services	Drainage routes, hot water and heating requirements, electrical work and ventilation.
Specification and completion	Windows, roof finishes, joinery, plastering, decoration and the agreed handover information.

The written quotation identifies inclusions, exclusions, supply responsibilities and any provisional items. Confirm VAT treatment and payment stages for the agreed package.

Compare quotation scopes

Does a loft conversion need planning permission?

Some roof enlargements to houses can use permitted development rights, provided every relevant limit and condition is met. A dormer is not automatically permitted: its position, size, roof height and the property’s planning restrictions matter. The householder rights do not apply to flats, and roof enlargements in conservation areas are excluded from this route.

See the dormer planning limits

A mansard proposal needs its planning position checked for your property. Building regulations, structural design and any party-wall procedures are separate matters. Ask your designer to confirm the approval route before work starts.

Check the government’s householder permitted-development guidance ↗

How long does a loft conversion take?

Allow separately for surveys and design, permissions and agreements, ordering and the construction programme. During the build, roof and structural work comes before weatherproofing, first-fix services, insulation and linings, followed by fitting and finishes. The stair opening and work to occupied rooms have to be planned into that sequence.

We agree a project-specific programme once the design, scope, access and key deliveries are understood. Ask us which facilities or rooms will be affected, when the stair connection is planned and what must be ready before each stage can go ahead.

Compare stair positions and small-landing options

Questions before you start

Can you tell if my loft is suitable from photographs?

Photographs are useful for the first conversation, but dimensions, structure, access and the proposed stair route need assessment before feasibility and scope are confirmed.

Can you build from our architect’s drawings?

Yes. Send the latest drawings with the structural information and specifications. We will point out gaps and clarify the construction package before pricing.

Is a loft conversion less disruptive than an extension?

That depends on the house and the sequence. Roof access, forming the stairs and connecting services can affect occupied rooms, so disruption has to be planned for your project.

What to send for a useful quotation

Send the postcode, loft and roof photographs, existing and proposed plans, planning status and structural details if available. Explain the rooms you want, whether a bathroom is included and which parts of the house will remain occupied.

Related work

Roof repairs

Carpentry and fitted joinery

Home refurbishment

Further guidance

Planning Portal: loft conversion permissions ↗

Planning Portal: loft floors and internal elements ↗

Before disturbing existing textured ceilings or concealed materials, resolve the relevant survey information. Read our Artex and asbestos preparation guidance.

Loft conversions in London

Tell us about your loft.