Westminster, London
Loft conversion drawings in Westminster
Loft conversion drawings in Westminster start at £695 including VAT. The council's roof guidance is cautious: it asks for overhanging and gabled roofs to be kept as built, and with 56 conservation areas to cross, the right design here is often a small, quiet one at the back.
From £695 (VAT included)
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- Fixed fees, VAT included
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Westminster's roof guidance for loft conversions
The council's Roofs SPG, titled Roofs: a guide to alterations and extensions on domestic buildings SPG, is the document officers use. On overhanging and gabled roofs its position is plain: they should be kept in their original form, and only small dormers or rooflights at the rear or the sides may be acceptable. That wording comes from the Roofs SPG, in its section on overhanging and gabled roofs.
In practice it changes what we propose. A hip-to-gable change, or a large dormer taking in the whole slope, runs against that guidance on the types of roof it describes. A modest rear dormer, or rooflights set into the slope, has a much better chance of being read as appropriate. For mews houses, the council also publishes the Mews: a guide to alterations SPG, which we read alongside.
The policy underneath both is the City Plan 2019-2040 (2026), adopted in 2,026. We design to the guidance, not around it, and tell you early if the roof you have is not suited to a conversion.
Local figures for Westminster
| Measure | Value | Period | Source |
|---|---|---|---|
| Conservation areas | 56 named conservation areas published by the council | — | planning.data.gov.uk |
| Article 4 directions | 10 Article 4 directions published by the council | — | planning.data.gov.uk |
| Article 4 direction areas | 10 Article 4 direction area polygons published by the council | — | planning.data.gov.uk |
| Listed building entries | 4,015 list entries (Historic England, within the LPA boundary) | — | planning.data.gov.uk |
| Households living in a house | 10.2 % of households living in a house or bungalow (detached, semi-detached or terraced) | Census 2021 | nomisweb.co.uk |
| Householder decisions | 366 decisions | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications granted | 82 % | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications decided in time | 79 % decided within 8 weeks or an agreed extended period | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| GPDO 2015 Sch 2 Pt 1 Class B, para B.1(d) | 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume | — | legislation.gov.uk |
| Class B, para B.1(c) | No enlargement beyond the plane of a roof slope that forms the principal elevation and fronts a highway | — | legislation.gov.uk |
| Class B, para B.1(f) | Class B roof enlargements are not permitted development on article 2(3) land | — | legislation.gov.uk |
| Approved Document K 2013, para 1.13, Diagram 1.4 | 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) | — | gov.uk |
| Approved Document B Vol 1, para 2.21 | New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30) | — | gov.uk |
A blank value means the figure has not been published, not that there are none. Check your own address with the council.
Householder applications by street in Westminster
| Street | Applications | Approved |
|---|---|---|
| Randolph Avenue | 16 | 79% |
| Ashworth Road | 13 | 85% |
| Clifton Hill | 11 | 70% |
| Ponsonby Place | 10 | 100% |
| Lancaster Mews | 9 | 38% |
| Westbourne Park Road | 9 | 88% |
| Carlton Hill | 8 | 86% |
| Kilburn Lane | 8 | 86% |
| Sutherland Place | 8 | 63% |
| Wilton Row | 8 | 100% |
| Caroline Close | 7 | 33% |
| Chester Row | 7 | 100% |
| Greenberry Street | 7 | 57% |
| Hereford Road | 7 | 60% |
| Hyde Park Gardens Mews | 7 | 75% |
Loft enlargement in section: the permitted development limits
A dormer on the rear slope, with the limits that decide whether it needs planning permission.
- A · Extra roof volume allowed
- 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume
- B · Set-back from the eaves
- Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension)
- C · Height limit
- No part higher than the highest part of the existing roof
Conservation areas, Article 4 and listed buildings
Westminster has 56 conservation areas, and a roof enlargement is not permitted development inside one. The borough also has 10 Article 4 directions covering 10 areas, and 1 World Heritage Site, so a good part of the borough has a layer of control beyond the national rules.
Heritage is heavy here. Historic England lists 4,015 entries in the borough, and a listed house needs listed building consent for nearly any change to its roof. If your building is listed, the question is whether any roof conversion is possible, and the answer shapes the whole project.
Where a house does qualify as permitted development, a Lawful Development Certificate in Westminster confirms it in writing. Everything else goes to householder planning, drawn as in our planning drawings in Westminster.
Houses are the minority in Westminster
Only 10.2 per cent of households here live in a house, and 27.4 per cent own their home. Much of the housing is flats, which have no permitted development right for roof enlargement at all, and many of them share a roof with other owners.
For a flat, we therefore start with the lease and the freeholder, as well as the roof. Who owns the roof space, who must consent and whether the building can take the extra load are all settled before we spend time on a design. For a house, the survey tells us what the roof can hold.
Surveying before the design
A Westminster roof may be a pitch, a mansard, a valley roof or a mews roof with very little height. We survey the roof form, the parapets and the party walls on one datum with the floors below, and note where the stair can rise.
The survey also settles the headroom question that building regulations ask of every new stair, and the fire protection that a new storey needs. Both flow into the building regulations drawings in Westminster once the design is agreed.
How Westminster decides householder applications
In its latest published year the council decided 366 householder applications and granted 82 per cent. 79 per cent were decided within eight weeks or an agreed extension, so it is worth allowing a little more time than the statutory period.
Those figures cover every household project in the borough. They are a guide to timing, not a prediction for your roof.
Price, contents and nearby boroughs
A Westminster loft set has the existing and proposed floor plans, roof section, elevations and location plans. It starts at £695 including VAT, with the fee agreed before you commit. A second chartered technologist checks each sheet, and if the council asks for changes we redraw them at no charge until the application is decided.
A rear dormer is covered by dormer loft conversion drawings in Westminster, and rooflight schemes by Velux loft conversion drawings in Westminster. The whole range is at architectural drawings in Westminster. Next door, see Camden and Kensington and Chelsea.
What you receive
Related pages
Other services in Westminster
Questions
Will Westminster allow a hip-to-gable loft conversion?
The council's Roofs SPG says overhanging and gabled roofs should be kept in their original form, with only small dormers or rooflights at the rear or sides likely to be acceptable. We would check the specific roof before offering a view.
Do I need planning permission for a loft conversion in Westminster?
Very often, yes. Inside any of the borough's 56 conservation areas, a roof enlargement is not permitted development, and flats have no such right at all. A Lawful Development Certificate can confirm the rare house that qualifies.
How much do loft conversion drawings cost in Westminster?
From £695 including VAT, fixed before you commit. Council fees are separate.
Does a mews house follow different rules?
Mews houses sit under the same national rules, but the council also publishes the Mews: a guide to alterations SPG for alterations to them, and we read it as part of the design.
Sources and dates
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- nomisweb.co.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
- legislation.gov.uk, retrieved
- gov.uk, retrieved
- gov.uk, retrieved
- westminster.gov.uk, retrieved
- westminster.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- nomisweb.co.uk, retrieved
- Contains public sector information licensed under the Open Government Licence v3.0.
- Contains OS data © Crown copyright and database right 2026.
- Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.
- Contains Historic England data © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026.
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