Purley loft conversion drawings from a published fixed fee
A Purley loft conversion starts with drawings, and ours start from £695 with no VAT to add for a rear dormer designed under permitted development. Purley falls under Croydon, so the council's own decision figures below tell you how householder applications fare locally.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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What a rear dormer drawing set costs
Our published starting fixed fee for rear dormer loft conversion drawings under permitted development is £695, with no VAT to add. It comes from our public price list, and the same figure is shown to everyone.
That is the figure for the dormer route. A scheme that needs a full planning application, or one that sits in a designated area, is a different job.
How much roof space you can add without planning permission
Permitted development for roof additions is set by Class B of Part 1 in Schedule 2 of the General Permitted Development Order. The volume limit depends on the house. A terrace house may add up to 40 cubic metres to the roof space. Any other house may add up to 50 cubic metres.
The allowance counts what you add, not the loft you already have. Your drawings need to show the new volume clearly enough to test it against that limit. Other limits and conditions sit in the same class, so the volume is one check, not the only one.
Across the Planning Inspectorate's casework database, 287 householder appeals in Croydon were decided between 2021 and 2026, and 39% were allowed.
Is your Purley house terraced, or something else?
Terraced houses get the smaller allowance, so a mid-terrace or end-of-terrace home is held to 40 cubic metres. A semi-detached or detached house falls under the other-case figure of 50 cubic metres.
If you are unsure which category applies to your house, check before you design the dormer around the wrong number. Getting it wrong early means redrawing later.
How Croydon householder applications have gone
Purley is in the London Borough of Croydon. Our analysis of the government's planning application statistics shows Croydon decided 786 householder applications across the four quarters from 2025 Q3 to 2026 Q2, and 87% of those were granted.
On speed, 95% of householder decisions (prior approvals excluded) were made within eight weeks over the same period. Figures like these describe the past year, not your application.
What happens when a householder case goes to appeal
Across the Planning Inspectorate's casework database, 287 householder appeals in Croydon were decided between 2021 and 2026, and 39% were allowed.
Read that carefully. Only refused applications reach appeal, so the allowed share says little about a typical application.
Conservation areas and proving a loft is lawful
Croydon has 20 live conservation areas on the government's planning data platform. If your Purley street sits inside one, check the designation before you assume the permitted development route is open to you.
If you build under permitted development and want written proof, you can apply for a certificate of lawful development. Croydon decided 1,005 of them over the eight quarters from 2024 Q3 to 2026 Q2, which shows how routine the route is for the borough.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| £695 | DrawingsDirect starting fixed fee for rear dormer loft conversion permitted development drawings, with no VAT to add, from the published price list | drawingsdirect.co.uk |
| 40 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B.1(d)(i): roof additions may add up to 40 cubic metres to the roof space of a terrace house (source wording: "40 cubic metres in the case of a terrace house") | www.legislation.gov.uk |
| 50 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B.1(d)(ii): roof additions may add up to 50 cubic metres to the roof space of any other house (source wording: "50 cubic metres in any other case") | www.legislation.gov.uk |
| 786 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 87% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 95% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 287 | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 39% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 20 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 14 Aug 2026) | www.planning.data.gov.uk |
| 1,005 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
Photographs: GRALISTAIR (CC BY-SA 4.0); GRALISTAIR (CC BY-SA 4.0); David Hawgood (CC BY-SA 2.0).
