Rear dormer drawings for Blean Forest roofs — the box across the back slope that turns a low attic into a full-height room, drawn to Canterbury City Council's guidance and the volume limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Canterbury City Council granted 97% of the householder planning decisions it made in its latest published year — 10 points above the 87% England-wide householder average. Blean Forest contains ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ), BLEAN conservation areas (ALLCROFT GRANGE ( HACKINGTON ) designated 1995), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
Class A and Class B set the thresholds — a rear dormer to 40m³ on a terrace or 50m³ on a semi or detached, and a single-storey rear extension to 3m on a terrace or 4m on a detached house — beyond which Canterbury City Council needs a full application. Blean Forest carries at least one Article 4 direction, and conservation areas including ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ) and BLEAN remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Blean Forest is determined against an 8-week statutory target.
ALLCROFT GRANGE ( HACKINGTON ) (conservation area designated in 1995), AMERY COURT ( BLEAN ) (conservation area designated in 1995), BLEAN (conservation area designated in 1994), CANTERBURY ( WHITSTABLE ROAD ) Registered 04.12.1996 (conservation area designated in 1996), CANTERBURY AND WHITSTABLE RAILWAY (HACKINGTON & BLEAN) (conservation area designated in 1995), HOTHE COURT (conservation area designated in 1994), the Tyler Hill Conservation Area. Registered 27.03.1995 (conservation area designated in 1995), Hackington (civil parish within Blean Forest), Harbledown and Rough Common (civil parish within Blean Forest) and Blean (civil parish within Blean Forest) — these are the Blean Forest pockets our drawings cover most. Heritage designations here include ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ), BLEAN, CANTERBURY ( WHITSTABLE ROAD ) Registered 04.12.1996, CANTERBURY AND WHITSTABLE RAILWAY (HACKINGTON & BLEAN), HOTHE COURT and the Tyler Hill Conservation Area. Registered 27.03.1995. Canterbury City Council weighs each proposal against the adopted Canterbury local plan and Canterbury City Council's design guidance for householder work, where the 2,640 homes here are 17% 1983-1992, 16% 1930-1939, 14% 1955-1964, which is what sets the realistic roof and rear-projection options. On roofs the borough is trussed-rafter roofs typical of 1980s building and hipped roofs with shallow pitches typical of 1930s building, over 1980s estate houses (17% of 2,640 homes), 1930s semi-detached and detached houses (16%) and late-1950s and early-1960s houses (14%).
Heritage designation is the single biggest variable in Blean Forest, and it is address-specific: ALLCROFT GRANGE ( HACKINGTON ) (conservation area designated in 1995), AMERY COURT ( BLEAN ) (conservation area designated in 1995), BLEAN (conservation area designated in 1994), CANTERBURY ( WHITSTABLE ROAD ) Registered 04.12.1996 (conservation area designated in 1996), CANTERBURY AND WHITSTABLE RAILWAY (HACKINGTON & BLEAN) (conservation area designated in 1995), HOTHE COURT (conservation area designated in 1994) and the Tyler Hill Conservation Area. Registered 27.03.1995 (conservation area designated in 1995). Inside those boundaries permitted development is curtailed and Canterbury City Council assesses materials, window detail and roof form against the area's own appraisal, so a scheme that would be waved through two streets away can need a full application here.
Beyond the designated areas, Blean Forest takes in Hackington, Harbledown and Rough Common and Blean. Canterbury City Council has 463 recorded Article 4 directions — check the address before assuming PD applies in Blean Forest.
On stock, Blean Forest is 1980s estate houses (17% of 2,640 homes), 1930s semi-detached and detached houses (16%) and late-1950s and early-1960s houses (14%) — which is why trussed-rafter roofs typical of 1980s building and hipped roofs with shallow pitches typical of 1930s building govern what a loft or rear projection can realistically be. Canterbury City Council decided 580 householder applications in the latest published year and granted 97%, with 43% issued inside the eight-week target. We work from the council's own published record.
The full build-period split for Blean Forest runs pre-1900 11% (280 homes), 1900-1918 2% (40 homes), 1919-1929 2% (60 homes), 1930-1939 16% (420 homes), 1945-1954 8% (200 homes), 1955-1964 14% (370 homes), 1965-1972 10% (260 homes), 1973-1982 7% (190 homes), 1983-1992 17% (440 homes), 1993-1999 5% (130 homes) and 2000-2008 5% (130 homes). That distribution is why pre-1900 detailing dominates the drawings here, and it is measured from council-tax records rather than assumed from the street name.
Canterbury City Council also decides for Chestfield, Gorrell, Herne & Broomfield, Heron, St Stephen's, Westgate, Wincheap and Little Stour & Adisham, so a decision in Blean Forest sits inside a wider pattern of decisions we track across the same authority — useful when an officer cites a precedent from the next area over.
The Article 4 directions recorded for this council include 1 AND 2 CHURCH COTTAGES, CHURCH LANE, NACKINGTON, 1 BOURNE COTTAGES, THE STREET, BISHOPSBOURNE, 1 BOX TREE COTTAGES, BOLTS HILL and 1 BUTTS COTTAGES, LOWER HARDRES. Each removes a specific permitted-development right inside its own boundary, which is why the check is done on the address rather than on the town.
Published figures for Blean Forest and Canterbury City Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Blean Forest |
|---|---|
| Dwellings recorded | 2,640 |
| Built pre-1900 | 280 (11%) |
| Built 1900-1918 | 40 (2%) |
| Built 1919-1929 | 60 (2%) |
| Built 1930-1939 | 420 (16%) |
| Built 1945-1954 | 200 (8%) |
| Built 1955-1964 | 370 (14%) |
| Built 1965-1972 | 260 (10%) |
| Built 1973-1982 | 190 (7%) |
| Built 1983-1992 | 440 (17%) |
| Built 1993-1999 | 130 (5%) |
| Built 2000-2008 | 130 (5%) |
| Built before 1919 | 12% |
| Built 1919–1939 | 18% |
| Built 1945–2008 | 65% |
| Conservation areas in Blean Forest | 7 (ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN )…) |
| Conservation areas district-wide | 98 |
| Article 4 directions recorded | 463 |
| Householder applications decided | 580 |
| Householder applications granted | 97% |
| Decided within 8 weeks | 43% |
Dwelling stock from VOA council-tax data at 31 March 2025; conservation-area and Article 4 counts from planning.data.gov.uk (MHCLG); decision figures are Canterbury City Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The box dormer is the workhorse loft, and most of Blean Forest is built for it — the borough runs to 1980s estate houses (17% of 2,640 homes), 1930s semi-detached and detached houses (16%) and late-1950s and early-1960s houses (14%) under trussed-rafter roofs typical of 1980s building and hipped roofs with shallow pitches typical of 1930s building, and a flat-roofed box across the rear slope is the cheapest cubic metre of full-height space those roofs give up. Canterbury City Council tests the dormer against the adopted Canterbury local plan and Canterbury City Council's design guidance for householder work, 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. Blean Forest contains ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ), BLEAN conservation areas (ALLCROFT GRANGE ( HACKINGTON ) designated 1995), so materials, fenestration and roof form are assessed against the appraisal, so the cheeks, the window line and the material are drawn to answer it rather than invite a query.
Where Blean Forest's streets are protected — ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ), BLEAN, CANTERBURY ( WHITSTABLE ROAD ) Registered 04.12.1996, CANTERBURY AND WHITSTABLE RAILWAY (HACKINGTON & BLEAN), HOTHE COURT and the Tyler Hill Conservation Area. Registered 27.03.1995 among them — the Class B dormer right is switched off and even a modest rear box needs consent. Canterbury City Council has 463 recorded Article 4 directions — check the address before assuming PD applies in Blean Forest. We confirm the designation before the box is sized.
Many rear dormers in Blean Forest are permitted development, but the volume and position decide it. You will normally need a full application to Canterbury City 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 Canterbury City Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Canterbury City Council granted 97% of its householder applications in the year to 31 March 2026, and ALLCROFT GRANGE ( HACKINGTON ) shapes what is approved here. 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, England, 1 April 2025 - 31 March 2026). 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 ALLCROFT GRANGE ( HACKINGTON ), AMERY COURT ( BLEAN ) and BLEAN, 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 trussed-rafter roofs typical of 1980s building, this returns a full-height double and en-suite from what was standing-room-only, usually inside the permitted-development volume.
The 2,640 homes here are 17% 1983-1992, 16% 1930-1939, 14% 1955-1964, which is what sets the realistic roof and rear-projection options. 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 Canterbury City 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 Blean Forest dormers come up most often:
Dormer loft drawings for ALLCROFT GRANGE ( HACKINGTON )'s conservation area designated in 1995 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Dormer loft drawings for AMERY COURT ( BLEAN )'s conservation area designated in 1995 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Dormer loft drawings for BLEAN's conservation area designated in 1994 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Dormer loft drawings for CANTERBURY ( WHITSTABLE ROAD ) Registered 04.12.1996's conservation area designated in 1996 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Dormer loft drawings for CANTERBURY AND WHITSTABLE RAILWAY (HACKINGTON & BLEAN)'s conservation area designated in 1995 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Dormer loft drawings for HOTHE COURT's conservation area designated in 1994 — volume-checked, set-back-detailed and drawn to Canterbury City Council's guidance.
Whether a dormer in Blean Forest 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 Canterbury City 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 ALLCROFT GRANGE ( HACKINGTON ) and AMERY COURT ( BLEAN ), Class B dormer rights are removed and every dormer needs a full application.
A fixed process built around how Canterbury City Council validates and decides dormer applications — most drawings are submission-ready within seven days of survey.
Send us your Blean Forest 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 Canterbury City 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 Canterbury City Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Canterbury City 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 Blean Forest you will need a full application to Canterbury City Council for a front or side dormer, a box that exceeds the volume, and any dormer in a conservation area such as ALLCROFT GRANGE ( HACKINGTON ) and AMERY COURT ( BLEAN ), 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 Blean Forest 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. Canterbury City 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 Canterbury City 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 Blean Forest 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 Canterbury City 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. This applies to your Blean Forest address specifically.
If your dormer is permitted development, a lawful development certificate from Canterbury City 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. This applies to your Blean Forest address specifically.
We price each Blean Forest 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 Canterbury City 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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