Hip-to-gable loft conversion drawings in Westminster

A very protected borough

Westminster publishes 56 conservation areas and 10 Article 4 directions, and Historic England lists 4,015 entries inside the boundary. The borough also contains 1 World Heritage Site. 23 places are on the Heritage at Risk Register.

With that much protection, Class B is lost for a large share of the housing stock, so many a Westminster roof job goes to the council as a planning application, and a listed house also needs listed building consent. Only 10.2 per cent of households live in a house, so many enquiries turn out to be flats, which have no householder right in any case.

How Westminster handles householder cases

The council decided 366 householder applications in its latest year and granted 82 per cent, with 79 per cent decided in time. Those figures cover all household work, from windows to extensions, and they tell you about the council's pace more than about any roof.

Because the borough has so many listed and conservation-area addresses, our drawings are written to be read by a conservation officer as well as a planning officer. That means measured existing elevations, a clear roof plan and a section that shows what changes and what stays.

Where permitted development can still apply

Some Westminster houses sit outside every designation. For those, the question is the national tests. The volume limit is 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume, and a gable needs to stay inside this condition: No part of the enlargement may extend beyond the outside face of any external wall of the original house (except where joining a rear or side extension roof).

If you pass, a Lawful Development Certificate in Westminster fixes the position in writing. If you do not, planning drawings in Westminster cover the application. The council received 138 certificate applications in its latest return, so it handles them regularly.

The certificate is not a formality. It is the council's written finding that your roof work was lawful, and it needs drawings that prove the volume and the position of the new wall. We prepare those from the survey, so the numbers on the sheets and the numbers on the roof agree. A purchaser's solicitor will ask for the document at sale, which is the main reason owners choose to apply even when building without one is possible.

Stair, fire route and technical drawings

Tall Westminster townhouses make the new loft stair a design problem in itself. Where full height cannot be reached, the Building Regulations accept this: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width). On a narrow house, we test that on the section before we fix the roof shape.

The technical drawings that follow are described in our building regulations drawings in Westminster, and roofs where a gable is not appropriate are covered under loft conversion drawings in Westminster.

Mews houses and narrow terraces

Westminster's smaller houses raise their own questions. Mews buildings are covered by the separate guide, Mews: a guide to alterations SPG, which concentrates on the scale and character of those small streets. A gable on a mews roof changes a skyline that the whole group shares, and the proposal has to respect it.

Narrow terraced townhouses have a different problem: shared party walls, matching roof pitches and chimney stacks that serve several houses. A hip-to-gable proposal is therefore drawn with the roofs next door as part of the existing elevation, so the officer sees the whole group, and a party wall notice is normally considered at the same time.

Fee, survey and sign-off

We do not publish a fee for this service. The quote is fixed after the constraints check, VAT included. We survey on one datum, show you the scheme in plan and 3D, freeze the design when you choose, and a second chartered technologist checks each sheet. For the borough context see architectural drawings in Westminster, and for the service overall the hip-to-gable overview.