Rear dormer drawings for Lewisham roofs — the box across the back slope that turns a low attic into a full-height room, drawn to Lewisham Council's guidance and the volume limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Lewisham Council granted 90% of the householder planning decisions it made in its latest published year — 3 points above the 87% England-wide householder average. Policies resist the loss of family-sized houses, so conversions to flats face an added hurdle, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901) and Edwardian (1901–1910) housing stock sets the design brief on most streets.
Under Class B, a rear dormer stays permitted development up to 40m³ of added roof volume on a terrace or 50m³ on a semi-detached or detached house, while Class A allows a single-storey rear extension of 3m beyond the original rear wall on a terrace and 4m on a detached house before a full application is needed. Lewisham carries at least one Article 4 direction, and conservation areas including Blackheath, Telegraph Hill and Brockley remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Lewisham is determined against an 8-week statutory target.
Blackheath (grand villas and terraces on the Lewisham side of the heath), Brockley (long Victorian terraces within one of London's largest conservation areas), Telegraph Hill (hilly Victorian terraces framing the two parks), Deptford (Georgian survivals like Albury Street amid dense terraced streets), Forest Hill (Victorian villas and terraces stepping up the slopes) and Sydenham (Victorian terraces and semis toward the Crystal Palace ridge) — these are the Lewisham pockets our drawings cover most. Heritage designations here include Blackheath, Telegraph Hill, Brockley, Deptford High Street and Sydenham. Lewisham Council weighs each proposal against the Lewisham Local Plan and the borough's Alterations and Extensions SPD, where in the Brockley and Telegraph Hill conservation areas original slate roofs and front elevations are closely guarded. Brockley, Forest Hill and Deptford hold large numbers of houses long ago converted into flats and maisonettes, which carry no householder permitted-development rights.. On roofs the borough is London butterfly roofs on the Victorian terraces and gabled roofs on the villas, over Victorian terraces, Victorian and Edwardian villas and converted flats and maisonettes.
The box dormer is the workhorse loft, and most of Lewisham is built for it — the borough runs to Victorian terraces, Victorian and Edwardian villas and converted flats and maisonettes under London butterfly roofs on the Victorian terraces and gabled roofs on the villas, and a flat-roofed box across the rear slope is the cheapest cubic metre of full-height space those roofs give up. Lewisham Council tests the dormer against the Lewisham Local Plan and the borough's Alterations and Extensions SPD, 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. Policies resist the loss of family-sized houses, so conversions to flats face an added hurdle, so the cheeks, the window line and the material are drawn to answer it rather than invite a query.
Where Lewisham's streets are protected — Blackheath, Telegraph Hill, Brockley, Deptford High Street and Sydenham among them — the Class B dormer right is switched off and even a modest rear box needs consent. Lewisham operates Article 4 directions in conservation areas such as Brockley alongside controls resisting the conversion of family houses into flats, so works that are permitted development elsewhere routinely need an application here. We confirm the designation before the box is sized.
Many rear dormers in Lewisham are permitted development, but the volume and position decide it. You will normally need a full application to Lewisham 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 Lewisham Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Lewisham grants the large majority of householder applications, though its policy shielding family houses from conversion and its Victorian conservation areas shape roof and rear works street by street. 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 Blackheath, Brockley and Telegraph Hill, 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 London butterfly roofs on the Victorian terraces, this returns a full-height double and en-suite from what was standing-room-only, usually inside the permitted-development volume.
In the Brockley and Telegraph Hill conservation areas original slate roofs and front elevations are closely guarded. 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 Lewisham 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 Lewisham dormers come up most often:
Dormer loft drawings for Blackheath's grand villas and terraces on the Lewisham side of the heath — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Dormer loft drawings for Brockley's long Victorian terraces within one of London's largest conservation areas — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Dormer loft drawings for Telegraph Hill's hilly Victorian terraces framing the two parks — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Dormer loft drawings for Deptford's Georgian survivals like Albury Street amid dense terraced streets — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Dormer loft drawings for Forest Hill's Victorian villas and terraces stepping up the slopes — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Dormer loft drawings for Sydenham's Victorian terraces and semis toward the Crystal Palace ridge — volume-checked, set-back-detailed and drawn to Lewisham Council's guidance.
Whether a dormer in Lewisham 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 Lewisham 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 Blackheath and Telegraph Hill, Class B dormer rights are removed and every dormer needs a full application.
A fixed process built around how Lewisham Council validates and decides dormer applications — most drawings are submission-ready within seven days of survey.
Send us your Lewisham 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 Lewisham 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 Lewisham Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Lewisham 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 Lewisham you will need a full application to Lewisham Council for a front or side dormer, a box that exceeds the volume, and any dormer in a conservation area such as Blackheath and Telegraph Hill, 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 Lewisham 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. Lewisham 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 Lewisham 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 Lewisham 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 Lewisham 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 Lewisham 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 Lewisham 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 Lewisham 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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