In Croydon the roof volume is the figure that matters. The council asks for the calculation with a lawful development certificate application, and Class B stops at 40 or 50 cubic metres. We work it out before we draw.
Photo: Bill Boaden, BY-SA 2.0
Because the volume is the test. Class B of the permitted development order lets a house add up to 40 cubic metres of roof space if it is a terrace and 50 cubic metres in any other case, and the figure counts the volume of any earlier roof extension. Croydon's validation list, in its section on lawful development certificates, says that for roof extensions you should provide a calculation of the proposed roof space volume, plus a site plan, existing and proposed floor plans, elevations where external alterations are proposed, and a CIL additional information form.
A rear dormer on a 1930s semi in Purley or Sanderstead often lands near the 50 cubic metre line, and a hip-to-gable adds its own volume on top. Counting the volume badly is how a scheme that looks permitted becomes unlawful by a few cubic metres. Our survey measures the roof, and the drawings show the calculation, so the certificate application is ready to submit.
If the conversion does not fit Class B, or the street is in a conservation area, a householder application is judged on the Local Plan. Croydon revoked its Suburban Design Guide on 25 July 2022, so older sources that quote its dormer rules are out of date; the council states that the guide is no longer used as guidance for decisions.
The May 2026 validation list sets out four items for a lawful development certificate involving the roof.
| Item | What Croydon says |
|---|---|
| Roof volume | A calculation of the proposed roof space volume for roof extensions |
| Plans | Site plan, existing and proposed floor plans |
| Elevations | Where external alterations are proposed |
| CIL | CIL additional information form |
Croydon Council, Local Validation List, May 2026, Other Application Types.
The fee includes our measured visit. The bracketed figure applies if you already have measured drawings.
Croydon has 21 conservation areas, and three have Article 4 directions: Chatsworth Road, The Waldrons and Kenley Aerodrome. In Chatsworth Road the direction, in force since 21 January 2016, removes the rights for all alterations to the roof of a dwelling house and for its extension, improvement or other alteration, so a loft there is a full application.
For example, a house on Chatsworth Road cannot use Class B at all, while a similar house a few streets away outside the three areas can. We check the three areas and the council's map before we price the work.
In the year to June 2026 Croydon decided 527 householder applications with prior approvals set aside and 502 inside 8 weeks. That is a borough outcome, not a promise for your application.
Every figure is linked to the page or document we read.
Croydon's Local Validation List of May 2026 says that for roof extensions a certificate application should include a calculation of the proposed roof space volume.
Source: Croydon Council, Local Validation List, May 2026Croydon revoked its Suburban Design Guide (SPD2) on 25 July 2022, and it stopped being used as guidance from 26 July 2022.
Source: Croydon Council, Supplementary planning documents and guidanceCroydon has 21 conservation areas, with Article 4 directions in Chatsworth Road, The Waldrons and Kenley Aerodrome.
Source: Croydon Council, Conservation areasThe Chatsworth Road Article 4 direction came into force on 21 January 2016 and removes the right to make all alterations to the roof of a dwelling house.
Source: Croydon Council, Chatsworth Road conservation area Article 4 directionCroydon decided 527 householder applications between July 2025 and June 2026, prior approvals excluded, and 502 of them were decided within 8 weeks.
Source: MHCLG, Planning application statistics PS2, July 2025 to June 2026Class B permits a roof extension of up to 40 cubic metres on a terraced house and 50 cubic metres in any other case.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class BTell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
Not if it fits Class B: no more than 40 cubic metres added on a terrace or 50 on other houses, not on the street slope, not above the ridge, and the house is not a flat or in a conservation area. A certificate proves it.
A site plan, existing and proposed floor plans, elevations where the outside changes, a CIL additional information form and a calculation of the proposed roof space volume, according to the council's May 2026 validation list.
No. The council revoked SPD2 on 25 July 2022, and it has not been used as guidance for decisions since 26 July 2022. The Local Plan policies it supported remain in force.
Only with planning permission. The Article 4 direction, in force since 21 January 2016, removes the right to alter a dwelling house roof and to extend, improve or alter the house, so the usual permitted routes are closed.
£765 inc survey (£565 if you supply measured drawings) for a rear dormer. That covers the measured survey, the drawings and the submission, with free revisions until the council decides. Croydon's own application fee is separate.
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