Rear dormer drawings for Bexley roofs — the box across the back slope that turns a low attic into a full-height room, drawn to Bexley Council's guidance and the volume limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Bexley Council granted 88% of the householder planning decisions it made in its latest published year — 1 point above the 87% England-wide householder average. Green Belt at Crayford Marshes and Foots Cray Meadows tightly limits extensions on the borough's fringes, which is where a policy-literate drawing pack earns its keep. Its dominant Victorian (1837–1901), interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
Before permission is required, Class B allows 40m³ of added loft volume on a terrace and 50m³ on a semi or detached house, and Class A allows a 3m single-storey rear extension on a terrace or 4m on a detached house. Bexley carries at least one Article 4 direction, and conservation areas including Bexley Village, Danson Park and Upton remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Bexley is determined against an 8-week statutory target.
Old Bexley (the historic village strung along Bexley High Street), Bexleyheath (interwar semis around Danson Park and the Upton conservation area), Sidcup (1930s houses and older streets near Old Sidcup and Foots Cray), Erith (riverside terraces and postwar housing by the Thames), Crayford (Victorian and interwar homes along the industrial edge) and Welling (dense interwar semi-detached suburbs) — these are the Bexley pockets our drawings cover most. Heritage designations here include Bexley Village, Danson Park, Upton, Old Sidcup and Foots Cray. Bexley Council weighs each proposal against the Bexley Local Plan and the borough's design guidance for householder development, where hipped roofs on paired semis mean hip-to-gable and dormers are judged on bulk and the pair's balance. On roofs the borough is hipped roofs on the interwar and postwar semis and gabled roofs on the detached houses, over interwar and postwar semi-detached houses, detached houses on larger plots and riverside and Victorian terraces.
The box dormer is the workhorse loft, and most of Bexley is built for it — the borough runs to interwar and postwar semi-detached houses, detached houses on larger plots and riverside and Victorian terraces under hipped roofs on the interwar and postwar semis and gabled roofs on the detached houses, and a flat-roofed box across the rear slope is the cheapest cubic metre of full-height space those roofs give up. Bexley Council tests the dormer against the Bexley Local Plan and the borough's design guidance for householder development, and because permitted development turns on a number, the volume you propose against the volume you have left is the first thing an officer or a certificate checks.
That is why the arithmetic goes on the drawings. We calculate the box against the 40- or 50-cubic-metre allowance, count any earlier roof enlargement into the total, hold the flat roof below the ridge and set the face back off the eaves so the dormer reads as subordinate. Green Belt at Crayford Marshes and Foots Cray Meadows tightly limits extensions on the borough's fringes, so the cheeks, the window line and the material are drawn to answer it rather than invite a query.
Where Bexley's streets are protected — Bexley Village, Danson Park, Upton, Old Sidcup and Foots Cray among them — the Class B dormer right is switched off and even a modest rear box needs consent. Bexley applies Article 4 directions in conservation areas such as Bexley Village and Danson Park, and parts of the borough fall within Metropolitan Green Belt where extensions are firmly restricted. We confirm the designation before the box is sized.
Many rear dormers in Bexley are permitted development, but the volume and position decide it. You will normally need a full application to Bexley Council if any of these apply:
We draw the box within its volume allowance, the flat roof below the ridge and the face set back off the eaves — the three things a dormer stands or falls on — and submit a validation-complete pack, whether that is a lawful development certificate or a full householder application.
Below is Bexley Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Bexley approves a strong majority of householder applications, with Metropolitan Green Belt on its edges and the symmetry of paired suburban semis the main factors shaping approvals. A dormer is decided on volume and set-back, so a pack that shows the calculation and the eaves detail is cleared faster and refused less often than a DIY submission.
Source: MHCLG planning application statistics (householder decisions, rolling year). Compare every borough on our London approval-rate league table.
Tell 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.
Across Old Bexley, Bexleyheath and Sidcup, the dormer that goes through is the subordinate rear box: flat roof kept low, cheeks clad to recede, side windows obscure-glazed against overlooking, and the whole thing set back so the original eaves line still reads from the garden. On hipped roofs on the interwar and postwar semis, this returns a full-height double and en-suite from what was standing-room-only, usually inside the permitted-development volume.
Hipped roofs on paired semis mean hip-to-gable and dormers are judged on bulk and the pair's balance. We keep the box off the ridge, match the cheek material to the roof, and where the volume is already spent — or the street is designated — draw the dormer as a householder application composed to Bexley Council's roof-alteration guidance rather than push a certificate that would be refused.
We draw rear dormers on the terraced and semi-detached streets across the borough. A few of the neighbourhoods where Bexley dormers come up most often:
Dormer loft drawings for Old Bexley's the historic village strung along Bexley High Street — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Dormer loft drawings for Bexleyheath's interwar semis around Danson Park and the Upton conservation area — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Dormer loft drawings for Sidcup's 1930s houses and older streets near Old Sidcup and Foots Cray — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Dormer loft drawings for Erith's riverside terraces and postwar housing by the Thames — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Dormer loft drawings for Crayford's Victorian and interwar homes along the industrial edge — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Dormer loft drawings for Welling's dense interwar semi-detached suburbs — volume-checked, set-back-detailed and drawn to Bexley Council's guidance.
Whether a dormer in Bexley needs permission comes down to where it sits and how big the box is. This is how the cases compare.
| Dormer type | Permitted development? | What it gains | What Bexley Council checks |
|---|---|---|---|
| Rear box, within volume | Usually yes | Full-height room across the back | Volume total, 20cm eaves set-back |
| Rear box, over volume limit | No — full application | A larger room | How far over the allowance, bulk |
| Front or side dormer | No — full application | Light to the front rooms | Visibility from the street, character |
| Dormer in a conservation area | No — full application | Same space, extra scrutiny | Roof form and street appearance |
In conservation areas such as Bexley Village and Danson Park, Class B dormer rights are removed and every dormer needs a full application.
A fixed process built around how Bexley Council validates and decides dormer applications — most drawings are submission-ready within seven days of survey.
Send us your Bexley postcode and roof type. We confirm your conservation and Article 4 status, work out how much permitted-development volume you have left, and score your odds against live Bexley Council decisions.
We measure ridge and eaves heights, roof pitch and the existing loft floor — the numbers the volume calculation, the set-back and the head heights depend on.
Chartered designers develop the box to your brief, drawn inside the Class B volume limits or, where those are exhausted or removed, to Bexley Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Bexley Council issues its decision.
Often not. A rear box dormer within 40 cubic metres on a terrace, or 50 on a semi or detached house, set back at least 20 centimetres from the eaves and kept below the ridge, is usually permitted development. In Bexley you will need a full application to Bexley Council for a front or side dormer, a box that exceeds the volume, and any dormer in a conservation area such as Bexley Village and Danson Park, where those rights are removed.
The permitted-development limit is a volume, not a footprint: 40 cubic metres of added roof space on a terraced house and 50 on a semi-detached or detached one, and any earlier loft enlargement counts against that total. In Bexley the box must also sit below the ridge and back from the eaves. We measure your roof and calculate the exact volume you have left before drawing. Bexley Council is the decision-maker.
Not under permitted development. A dormer on the front roof slope, or one facing a highway, always needs a full application to Bexley Council, because it changes how the house reads from the street. Rear box dormers are far more likely to be approved — or to be permitted development outright — which is why almost every Bexley dormer we draw sits on the back slope.
Often, on a terrace or semi. If the dormer or the loft steelwork meets the party wall with your neighbour, the Party Wall etc. Act applies and notice must be served before work starts — separately from Bexley Council's planning decision. We flag the party-wall junction on the drawings so a surveyor can be appointed early and the build is not held up.
If your dormer is permitted development, a lawful development certificate from Bexley Council is council-stamped proof of it — worth holding, because a buyer's solicitor will ask for it when you sell. We prepare and submit the certificate with the same measured drawing pack that shows the box within its volume allowance.
We price each Bexley dormer individually, because the roof pitch and the volume left vary house to house, and send a fixed, no-obligation quote within one working day. It covers the full drawing pack with free revisions until Bexley Council approves, and we confirm at the outset whether your box is permitted development or needs an application. Call 020 7864 7245 to start.
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