Dormer loft conversion in Hayes
A dormer loft conversion in Hayes can be permitted development if it adds no more than 40 cubic metres to a terraced house and sits back 0.2 metres from the eaves. Bromley, the council for Hayes, granted 79% of its 1,609 householder decisions in the latest four quarters. Drawings start at £695.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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Where Hayes houses meet the Class B limits
The permitted development rules for roof extensions give a terraced house 40 cubic metres of added roof space, with a larger allowance for others. The enlargement must also be set back at least 0.2 metres from the eaves.
Both figures are measured on the drawing, so they can be checked against the existing roof.
Bromley grants about four in five householder cases
Our analysis of the MHCLG planning application statistics (table PS2) counts 1,609 householder decisions for Bromley in the four quarters to mid-2026, of which 79% were granted. Of the householder decisions that were not prior approvals, 90% came within eight weeks.
A grant rate in the high seventies means design matters. On a house that needs a full application, a modest dormer in matching tiles is a safer starting point than the largest box the volume allows. Our Bromley planning permission page covers the application steps.
Our analysis of table PS1 shows Bromley decided 1,030 certificates of lawful development over eight quarters, so a permitted dormer has a well-used way to be confirmed in writing.
Appeals in Bromley
Our analysis of the Planning Inspectorate casework database finds 563 householder appeals decided for Bromley between 2021 and 2026, and 37% were allowed. That is the history of other applicants, not a forecast for your roof.
It is a large sample, though, and it shows an inspector will sometimes overturn a refusal.
Designations: 73 conservation-area entries
Our analysis of the MHCLG Planning Data Platform lists 73 conservation-area entries for Bromley on the national register. Check the council's map for BR2 before you assume the permitted route is open. Our conservation area guide explains what changes if your house is inside one.
The certificate route and our fee
Our analysis of table PS1 shows Bromley decided 1,030 certificates of lawful development over eight quarters, so a permitted dormer has a well-used way to be confirmed in writing.
A rear dormer starts at £695 and an L-shaped dormer at £745. See our loft conversion drawings hub for the other loft types, or the Bromley floor plans page for the layouts.
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, from the published price list | drawingsdirect.co.uk |
| £745 | DrawingsDirect starting fixed fee for L-shaped dormer loft conversion permitted development drawings, 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 |
| 0.2 metres | GPDO 2015 Sch 2 Pt 1 Class B.2(b): a roof enlargement must be set back not less than 0.2 metres from the eaves, measured along the roof slope (source wording: "not less than 0.2 metres from the eaves") | www.legislation.gov.uk |
| 1,609 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 79% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 90% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 563 | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 37% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 73 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 19 Oct 2026) | www.planning.data.gov.uk |
| 1,030 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
Questions people ask
Do I need planning permission for a dormer in Hayes?
Which council decides applications in Hayes BR2?
How much is a dormer loft conversion drawing in Hayes?
Photographs: David Hawgood (CC BY-SA 2.0); GRALISTAIR (CC BY-SA 4.0).
