Barnet, London
Dormer loft conversion drawings in Barnet
Dormer loft conversion drawings for a Barnet house start at £695 including VAT. The first test the council applies is the size and position of the box: when the work is not permitted development, Barnet asks for a rear dormer to be inset 0.5 m from the eaves, the ridge and the edges of the original roof.
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How Barnet judges a dormer on a house roof
Barnet's guidance for roof work sits in the Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. It is blunt about the street side: a front dormer will generally not be supported unless dormers are already a common feature of that street. A rear dormer is the normal answer, and the same guidance gives it a margin of 0.5 m from the eaves, the ridge and the sides of the original roof.
That margin shapes the drawing more than people expect. On a narrow semi, three set-backs of that size take up part of the slope, so the dormer can come out smaller than the permitted development volume would allow. We draw the inset first, then fit the room, the stair landing and the window positions inside it. Side windows in the cheek follow their own condition, which is that Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor, so we place them with the neighbour in mind.
The volume allowance still matters when the house keeps its permitted rights: 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume. If a design needs more than that, or the house has lost its rights, the Barnet margin is the standard the officer will hold the drawing to.

Local figures for Barnet
| Measure | Value | Period | Source |
|---|---|---|---|
| Where not permitted development, rear dormers should be inset at least 0.5 metres from the eaves, ridge and edges of the original roof. | 0.5 m | — | barnet.gov.uk, SDDG SPD Part 4 (extensions), p.22, para 4.87 |
| Conservation areas | 16 named conservation areas published by the council | — | planning.data.gov.uk |
| Article 4 directions | 15 Article 4 directions published by the council | — | planning.data.gov.uk |
| Article 4 direction areas | 48 Article 4 direction area polygons published by the council | — | planning.data.gov.uk |
| Listed building entries | 651 list entries (Historic England, within the LPA boundary) | — | planning.data.gov.uk |
| Householder decisions | 1,361 decisions | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications granted | 80.2 % | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications decided in time | 95.1 % decided within 8 weeks or an agreed extended period | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder appeals decided by the Planning Inspectorate | 413 householder appeals decided | decision dates 1 Jul 2021 to 30 Jun 2026 | assets.publishing.service.gov.uk |
| Householder appeals allowed | 50.6 % of householder appeals allowed | decision dates 1 Jul 2021 to 30 Jun 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, condition B.2(b)(i) | 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) | — | legislation.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 Barnet
| Street | Applications | Approved |
|---|---|---|
| Wolmer Gardens | 42 | 82% |
| Hampden Way | 36 | 86% |
| Oakleigh Park South | 36 | 77% |
| Marsh Lane | 35 | 91% |
| Millway | 34 | 93% |
| Sturgess Avenue | 34 | 94% |
| Uphill Road | 32 | 73% |
| Chanctonbury Way | 31 | 90% |
| Oakleigh Road North | 30 | 79% |
| Woodlands | 30 | 76% |
| Laurel Way | 29 | 76% |
| Mount Pleasant | 28 | 80% |
| Arlington Road | 27 | 80% |
| Berkeley Crescent | 27 | 100% |
| Longland Drive | 27 | 100% |
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
Article 4 directions and conservation areas in Barnet
Barnet has published 15 Article 4 directions, mapped as 48 separate areas, and 16 conservation areas. Where a direction removes roof rights, or where a conservation area applies, a dormer needs planning permission whatever its size.
Historic England records 651 listed entries inside the borough. A listed house needs listed building consent for roof alterations on top of any planning route, and that is a separate application with its own drawings.
Two neighbouring roofs can face different rules, so we check your address against all three before quoting a route. Where the house keeps its rights, a Lawful Development Certificate can confirm the design in writing. Where it does not, the dormer goes through householder planning on the same set of sheets, so nothing is drawn twice.
What Barnet decisions and appeals show for householder work
In its latest published year Barnet decided 1,361 householder applications and granted 80.2 per cent of them. 95.1 per cent were decided inside the statutory period or an agreed extension.
The Planning Inspectorate decided 413 householder appeals for the borough and allowed 50.6 per cent. An appeal can overturn a refusal, but it adds months, so we would rather get the dormer right at the first submission.
Both sets of figures cover every kind of householder project, not only dormers, and say nothing about your roof. We use them to plan the timetable and to explain the risk, not to forecast a result.
What the Barnet dormer loft conversion drawings include
A Barnet dormer set shows the existing and proposed floor plans, the roof in section with the dormer cheek and flat-roof build-up, and all elevations, together with the location and block plans. Building regulations set the stair headroom for a loft as follows: 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). We draw to that from the start, so the layout works before the structural engineer is involved. The new storey also brings a fire rule: 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). Both go on the plans and the specification, which keeps the later building regulations drawings consistent with the planning set.
The fixed price is £695 including VAT, quoted before you commit. A second MCIAT chartered architectural technologist checks every sheet before it goes to the council, and if the council asks for changes we redraw at no charge until approval.
If the roof suits a wider form, compare it with L-shaped dormer drawings in Barnet. If you want to see the plain alternative, loft conversion drawings in Barnet cover rooflight-only schemes.
Dormer drawings across north London
Neighbouring councils measure a dormer differently. See dormer loft conversion drawings in Haringey, in Enfield or in Hertsmere for their rules. For the borough as a whole, start at architectural drawings in Barnet, or read the national picture on the dormer loft conversion drawings hub.
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Questions
Do I need planning permission for a dormer in Barnet?
Often not, if the house keeps its permitted development rights and the dormer stays on the rear or a side slope within the volume allowance. A conservation area, an Article 4 direction or a listed house changes that, and we check the address first.
How far must a Barnet rear dormer sit from the roof edge?
Where the work is not permitted development, Barnet's extension guidance asks for an inset of 0.5 m from the eaves, ridge and edges of the original roof.
Will Barnet accept a dormer on the front of my house?
Generally not. The council's guidance supports a front dormer only where dormers are a common feature of the street. A rear dormer with front rooflights is the usual alternative.
How much do dormer loft conversion drawings cost in Barnet?
From £695 including VAT, fixed up front. Any council application fee is paid to the council separately.
Sources and dates
- barnet.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
- legislation.gov.uk, retrieved
- barnet.gov.uk, retrieved
- gov.uk, retrieved
- gov.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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