The fast route to a deep single-storey rear extension in South East Purbeck — up to 6 metres on an attached house or 8 on a detached one — via Dorset Council's prior approval scheme rather than a full planning application.
Dorset Council granted 95% of the householder planning decisions it made in its latest published year — 8 points above the 87% England-wide householder average. South East Purbeck contains Acton Conservation Area 1, Acton Conservation Area 2, Church Knowle Conservation Area conservation areas (Acton Conservation Area 1 designated 1975), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant Victorian (1837–1901) and postwar (1945–1970) 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. South East Purbeck carries at least one Article 4 direction, and conservation areas including Acton Conservation Area 1, Acton Conservation Area 2 and Church Knowle Conservation Area remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in South East Purbeck is determined against an 8-week statutory target.
Acton Conservation Area 1 (conservation area designated in 1975), Acton Conservation Area 2 (conservation area designated in 1975), Church Knowle (conservation area designated in 1981), Corfe Castle (conservation area designated in 1971), East Creech (conservation area designated in 1990), East Holme (conservation area designated in 1990), Kimmeridge (conservation area designated in 1975), Kingston (conservation area designated in 1975), Langton Matravers Conservation Area 1 (conservation area designated in 1976), Langton Matravers Conservation Area 2 (conservation area designated in 1976), Studland (conservation area designated in 1991), Worth Matravers (conservation area designated in 1975), Church Knowle (civil parish within South East Purbeck), East Holme (civil parish within South East Purbeck), East Stoke (civil parish within South East Purbeck), Kimmeridge (civil parish within South East Purbeck), Langton Matravers (civil parish within South East Purbeck) and Studland (civil parish within South East Purbeck) — these are the South East Purbeck pockets our drawings cover most. Heritage designations here include Acton Conservation Area 1, Acton Conservation Area 2, Church Knowle Conservation Area, Corfe Castle Conservation Area, East Creech Conservation Area, East Holme Conservation Area, Kimmeridge Conservation Area, Kingston Conservation Area, Langton Matravers Conservation Area 1, Langton Matravers Conservation Area 2, Studland Conservation Area and Worth Matravers Conservation Area. Dorset Council weighs each proposal against the adopted Dorset local plan and Dorset Council's design guidance for householder work, where the 1,930 homes here are 30% pre-1900, 10% 1945-1954, 9% 1983-1992, which is what sets the realistic roof and rear-projection options. On roofs the borough is steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and simple gabled and hipped roofs typical of early postwar building, over Victorian and earlier houses (30% of 1,930 homes), early postwar houses (10%) and 1980s estate houses (9%).
South East Purbeck's designated heritage is specific, and it is the first thing we check against your address: Acton Conservation Area 1 (conservation area designated in 1975), Acton Conservation Area 2 (conservation area designated in 1975), Church Knowle (conservation area designated in 1981), Corfe Castle (conservation area designated in 1971), East Creech (conservation area designated in 1990), East Holme (conservation area designated in 1990), Kimmeridge (conservation area designated in 1975), Kingston (conservation area designated in 1975), Langton Matravers Conservation Area 1 (conservation area designated in 1976), Langton Matravers Conservation Area 2 (conservation area designated in 1976), Studland (conservation area designated in 1991) and Worth Matravers (conservation area designated in 1975). Inside those boundaries permitted development is curtailed and Dorset 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, South East Purbeck takes in Church Knowle, East Holme, East Stoke, Kimmeridge, Langton Matravers and Studland. Dorset Council has 77 recorded Article 4 directions — check the address before assuming PD applies in South East Purbeck.
On stock, South East Purbeck is Victorian and earlier houses (30% of 1,930 homes), early postwar houses (10%) and 1980s estate houses (9%) — which is why steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and simple gabled and hipped roofs typical of early postwar building govern what a loft or rear projection can realistically be. Dorset Council decided 1,261 householder applications in the latest published year and granted 95%, with 78% issued inside the eight-week target. Those are the numbers our drawings are prepared against.
The full build-period split for South East Purbeck runs pre-1900 30% (570 homes), 1900-1918 3% (60 homes), 1919-1929 3% (60 homes), 1930-1939 7% (140 homes), 1945-1954 10% (190 homes), 1955-1964 8% (160 homes), 1965-1972 5% (100 homes), 1973-1982 8% (150 homes), 1983-1992 9% (170 homes), 1993-1999 5% (90 homes) and 2000-2008 3% (60 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.
Dorset Council also decides for Beacon, Beaminster, Blackmore Vale, Blandford, Chalk Valleys, Charminster St Mary's, Chickerell and Cranborne & Alderholt, so a decision in South East Purbeck 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 1-3 The Lane, Kingston, Corfe Castle, 10 Cornwall Road, Swanage, 6 Burlington Road, Swanage and Avon Castle & Matchams Park Estate. 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 South East Purbeck and Dorset Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | South East Purbeck |
|---|---|
| Dwellings recorded | 1,930 |
| Built pre-1900 | 570 (30%) |
| Built 1900-1918 | 60 (3%) |
| Built 1919-1929 | 60 (3%) |
| Built 1930-1939 | 140 (7%) |
| Built 1945-1954 | 190 (10%) |
| Built 1955-1964 | 160 (8%) |
| Built 1965-1972 | 100 (5%) |
| Built 1973-1982 | 150 (8%) |
| Built 1983-1992 | 170 (9%) |
| Built 1993-1999 | 90 (5%) |
| Built 2000-2008 | 60 (3%) |
| Built before 1919 | 33% |
| Built 1919–1939 | 10% |
| Built 1945–2008 | 48% |
| Conservation areas in South East Purbeck | 12 (Acton Conservation Area 1, Acton Conservation Area 2…) |
| Conservation areas district-wide | 311 |
| Article 4 directions recorded | 77 |
| Householder applications decided | 1,261 |
| Householder applications granted | 95% |
| Decided within 8 weeks | 78% |
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 Dorset Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The ordinary Class A limits stop a single-storey rear extension at 3 metres on an attached house and 4 on a detached one. The larger home extension scheme doubles both, on condition that the council is told first. That notification is not an application for permission — the council cannot refuse on design, materials or policy grounds. It can only consider the effect on the amenity of adjoining premises, and only if a neighbour actually objects during the 21-day consultation.
The other conditions still apply and are strict: single storey only, no higher than 4 metres, eaves no higher than the existing eaves, and no more than half the land around the original house covered. It is not available on designated land, so a house in a conservation area such as Acton Conservation Area 1 and Acton Conservation Area 2 cannot use it at all. Materials must be similar to the existing house, and the extension must not include a veranda, balcony or raised platform.
South East Purbeck is largely Victorian and earlier houses (30% of 1,930 homes), early postwar houses (10%) and 1980s estate houses (9%). South East Purbeck contains Acton Conservation Area 1, Acton Conservation Area 2, Church Knowle Conservation Area conservation areas (Acton Conservation Area 1 designated 1975), so materials, fenestration and roof form are assessed against the appraisal, which matters here because an objecting neighbour puts amenity squarely in front of a case officer. Dorset Council has 77 recorded Article 4 directions — check the address before assuming PD applies in South East Purbeck.
The scheme is available where all of these hold. Fail any one and it is a full application to Dorset Council instead:
We prepare the notification pack Dorset Council needs — plans, elevations, a site plan with the adjoining owners identified — and manage the 21-day neighbour consultation so the 42-day clock is not restarted by an incomplete submission.
Below is Dorset Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Dorset Council granted 95% of its householder applications in the year to 31 March 2026, and Acton Conservation Area 1 shapes what is approved here. Prior approval turns on neighbour amenity alone, so the drawings that matter are the ones showing the relationship to the boundary.
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 Acton Conservation Area 1, Acton Conservation Area 2 and Church Knowle, the notifications that clear without objection are the ones that treat the neighbour as the audience. We show the extension in section against the boundary, demonstrate the 45-degree daylight relationship to the nearest habitable window, and where the plot is tight we taper the depth away from the boundary rather than running the full 6 metres to the fence.
The 1,930 homes here are 30% pre-1900, 10% 1945-1954, 9% 1983-1992, which is what sets the realistic roof and rear-projection options. Where an objection does arrive, the council's assessment is narrow: loss of light, outlook and overbearing effect on the adjoining property, nothing else. A pack that has already answered those three points on the drawings usually survives an objection, whereas one that leaves them to the officer's imagination usually does not.
We prepare prior-approval notifications across South East Purbeck. A few of the areas where deep rear extensions come up most often:
Prior approval drawings for Acton Conservation Area 1 — conservation area designated in 1975 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Prior approval drawings for Acton Conservation Area 2 — conservation area designated in 1975 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Prior approval drawings for Church Knowle — conservation area designated in 1981 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Prior approval drawings for Corfe Castle — conservation area designated in 1971 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Prior approval drawings for East Creech — conservation area designated in 1990 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Prior approval drawings for East Holme — conservation area designated in 1990 — dimensioned to the 6m and 8m limits and prepared for Dorset Council's neighbour consultation.
Same extension, two routes, very different tests.
| Route | Depth allowed | What the council may consider | Timescale |
|---|---|---|---|
| Ordinary Class A permitted development | 3m attached / 4m detached | Nothing — no application needed | Immediate |
| Larger home extension prior approval | 6m attached / 8m detached | Amenity of adjoining premises, only if a neighbour objects | 21-day consultation, 42-day determination |
| Full householder application | No fixed limit | Design, materials, policy, amenity, everything | 8-week target |
| Any of these on designated land | 3m / 4m only | Prior approval scheme unavailable | Full application beyond the limits |
Limits and procedure from the GPDO 2015, Schedule 2, Part 1, Class A and paragraph A.4, made permanent by amendment in 2019.
A process built around the 21-day consultation, which is where these schemes are won or lost.
Send us your South East Purbeck postcode and house type. We confirm whether the property is on designated land, whether the scheme is available, and what depth you can realistically take.
We measure the original rear wall, eaves height, boundary distances and the neighbouring windows that the amenity assessment will turn on.
We draw the extension to the 6m or 8m limit with the boundary relationship shown in section, and prepare the written description and adjoining-owner details Dorset Council needs to start the consultation.
We submit, track the 21-day consultation and the 42-day determination, respond to any objection on amenity grounds, and revise free until the decision.
Three metres on a terraced or semi-detached house and four on a detached one under ordinary permitted development. Under the larger home extension prior approval scheme those double to six and eight metres, provided you notify Dorset Council before starting and the conditions on height, materials and land coverage are met. The scheme is not available on designated land. This applies to your South East Purbeck address specifically.
It is a notification, not an application for permission. You tell Dorset Council what you intend to build, it writes to the adjoining owners, and they have 21 days to object. If nobody objects, you may build. If someone does, the council assesses the effect on the amenity of adjoining premises and must decide within 42 days. Design and policy are not in scope. This applies to your South East Purbeck address specifically.
The council then considers the impact on the amenity of the adjoining property — loss of light, loss of outlook, and overbearing effect — and nothing else. It cannot refuse because it dislikes the design or the materials. We prepare the drawings so those three questions are already answered in section and on the site plan, which is what usually carries an objected scheme through. This applies to your South East Purbeck address specifically. Dorset Council is the decision-maker.
No. The larger home extension scheme is unavailable on designated land, which includes conservation areas such as Acton Conservation Area 1 and Acton Conservation Area 2, national landscapes, national parks and world heritage sites. On those properties the ordinary 3-metre and 4-metre limits apply, and anything deeper needs a full householder application to Dorset Council. This applies to your South East Purbeck address specifically.
Twenty-one days for the neighbour consultation, and a maximum of 42 days from a valid submission for the council to determine it. If the council does not respond within 42 days you may proceed as notified. That deadline is the scheme's real advantage over a full application, and it is why validation completeness matters so much. This applies to your South East Purbeck address specifically. Dorset Council is the decision-maker.
Yes — always. Prior approval deals only with the planning position. A 6-metre rear extension still needs building control approval for foundations, structure, drainage, thermal performance and fire safety, and the beam over the opening into the existing house needs designing and calculating. We prepare both sets so the notified scheme is the buildable one. This applies to your South East Purbeck address specifically. Dorset Council is the decision-maker.
We quote each South East Purbeck scheme individually, because plot shape and the boundary relationship drive the work, and send a fixed, no-obligation quote within one working day. It covers the notification pack and free revisions until Dorset Council determines it. Call 020 7864 7245 to start.
Answer five quick questions and get a free planning score for your exact address — instantly. Then, if you want the full picture, unlock the detailed analysis: your council's live approval rates, local precedents, constraints on your street and a step-by-step route to permission.
Same fixed quotes, same fast drawings — wherever your project is.