Two-storey extension drawings for Cranborne & Alderholt homes — bedroom above, living space below, drawn against the 3-metre projection and 7-metre boundary rules and to Dorset Council's design guidance, delivered in days and revised free until your decision.
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. Cranborne & Alderholt contains Cranborne Conservation Area, Edmondsham Conservation Area, Wimborne St Giles Conservation Area conservation areas (Cranborne Conservation Area designated 1970), 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) 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 Dorset Council needs a full application. Cranborne & Alderholt carries at least one Article 4 direction, and conservation areas including Cranborne Conservation Area, Edmondsham Conservation Area and Wimborne St Giles Conservation Area remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Cranborne & Alderholt is determined against an 8-week statutory target.
Cranborne (conservation area designated in 1970), Edmondsham (conservation area designated in 1991), Wimborne St Giles (conservation area designated in 1975), Alderholt (civil parish within Cranborne & Alderholt), Cranborne (civil parish within Cranborne & Alderholt), Edmondsham (civil parish within Cranborne & Alderholt), Wimborne St. Giles (civil parish within Cranborne & Alderholt) and Woodlands (civil parish within Cranborne & Alderholt) — these are the Cranborne & Alderholt pockets our drawings cover most. Heritage designations here include Cranborne Conservation Area, Edmondsham Conservation Area and Wimborne St Giles Conservation Area. Dorset Council weighs each proposal against Dorset Council's adopted local plan and its householder design guidance, where the 2,160 homes here are 21% 1983-1992, 20% 1973-1982, 16% pre-1900, which is what sets the realistic roof and rear-projection options. On roofs the borough is trussed-rafter roofs typical of 1980s building and shallow trussed roofs typical of 1970s building, over 1980s estate houses (21% of 2,160 homes), 1970s and early-1980s houses (20%) and Victorian and earlier houses (16%).
Heritage designation is the single biggest variable in Cranborne & Alderholt, and it is address-specific: Cranborne (conservation area designated in 1970), Edmondsham (conservation area designated in 1991) and Wimborne St Giles (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, Cranborne & Alderholt takes in Alderholt, Cranborne, Edmondsham, Wimborne St. Giles and Woodlands. Dorset Council has 77 recorded Article 4 directions — check the address before assuming PD applies in Cranborne & Alderholt.
On stock, Cranborne & Alderholt is 1980s estate houses (21% of 2,160 homes), 1970s and early-1980s houses (20%) and Victorian and earlier houses (16%) — which is why trussed-rafter roofs typical of 1980s building and shallow trussed roofs typical of 1970s 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. We work from the council's own published record.
The full build-period split for Cranborne & Alderholt runs pre-1900 16% (350 homes), 1900-1918 6% (140 homes), 1919-1929 2% (40 homes), 1930-1939 2% (40 homes), 1945-1954 4% (80 homes), 1955-1964 3% (70 homes), 1965-1972 4% (80 homes), 1973-1982 20% (430 homes), 1983-1992 21% (460 homes), 1993-1999 9% (200 homes) and 2000-2008 4% (80 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 Chase, so a decision in Cranborne & Alderholt 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 Cranborne & Alderholt 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 | Cranborne & Alderholt |
|---|---|
| Dwellings recorded | 2,160 |
| Built pre-1900 | 350 (16%) |
| Built 1900-1918 | 140 (6%) |
| Built 1919-1929 | 40 (2%) |
| Built 1930-1939 | 40 (2%) |
| Built 1945-1954 | 80 (4%) |
| Built 1955-1964 | 70 (3%) |
| Built 1965-1972 | 80 (4%) |
| Built 1973-1982 | 430 (20%) |
| Built 1983-1992 | 460 (21%) |
| Built 1993-1999 | 200 (9%) |
| Built 2000-2008 | 80 (4%) |
| Built before 1919 | 23% |
| Built 1919–1939 | 4% |
| Built 1945–2008 | 65% |
| Conservation areas in Cranborne & Alderholt | 3 (Cranborne Conservation Area, Edmondsham Conservation Area…) |
| 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.
Adding at first floor changes the question the case officer asks. A single-storey extension is judged mostly on daylight and garden loss; a two-storey extension is judged on overlooking, bulk against the neighbouring roofline, and whether it reads as part of the house or bolted onto it. Cranborne & Alderholt is largely 1980s estate houses (21% of 2,160 homes), 1970s and early-1980s houses (20%) and Victorian and earlier houses (16%), and trussed-rafter roofs typical of 1980s building and shallow trussed roofs typical of 1970s building set what a matching roof actually means here.
The permitted-development route exists but is narrow: 3 metres of rear projection, a 7-metre stand-off from the rear boundary, eaves and ridge no higher than the original, and side-facing upper windows obscure-glazed and non-opening below 1.7 metres above floor level. Most two-storey schemes fail one of those, usually the 7-metre boundary rule on a shorter garden, and go in as a full application instead. We establish which route applies before designing, because it changes the drawing set.
Cranborne & Alderholt contains Cranborne Conservation Area, Edmondsham Conservation Area, Wimborne St Giles Conservation Area conservation areas (Cranborne Conservation Area designated 1970), so materials, fenestration and roof form are assessed against the appraisal. Dorset Council has 77 recorded Article 4 directions — check the address before assuming PD applies in Cranborne & Alderholt.
Some two-storey rear extensions are permitted development. You will need a full application to Dorset Council if any of these apply:
We set the projection and boundary distance on the site plan, prove the roof-pitch match on the elevations, and specify obscure glazing on the side windows — the three things Dorset Council checks first — then submit a validation-complete pack.
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 Cranborne Conservation Area shapes what is approved here. Two-storey schemes attract more neighbour comment than any other householder work, so the overlooking and daylight case has to be made on the drawings.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
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Across Cranborne, Edmondsham and Wimborne St Giles, the schemes that succeed set the first floor back from the ground floor, keep the ridge below the original, and treat the flank wall as blank or obscure-glazed. On 1980s estate houses (21% of 2,160 homes), matching the eaves line matters more than matching the brick: an extension that carries the existing eaves through reads as original even in a different material.
The 2,160 homes here are 21% 1983-1992, 20% 1973-1982, 16% pre-1900, which is what sets the realistic roof and rear-projection options. We draw the 45-degree daylight test from the neighbour's nearest habitable window, show the window positions in section, and set out the steel and foundation implications early — a two-storey extension changes the load path, so the structural design and the planning design have to be developed together rather than in sequence.
We draw two-storey extensions across Cranborne & Alderholt. A few of the areas where they come up most often:
Two storey extension drawings for Cranborne — conservation area designated in 1970 — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
Two storey extension drawings for Edmondsham — conservation area designated in 1991 — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
Two storey extension drawings for Wimborne St Giles — conservation area designated in 1975 — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
Two storey extension drawings for Alderholt — civil parish within Cranborne & Alderholt — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
Two storey extension drawings for Cranborne — civil parish within Cranborne & Alderholt — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
Two storey extension drawings for Edmondsham — civil parish within Cranborne & Alderholt — dimensioned against the 3m and 7m limits and drawn to Dorset Council's guidance.
The first-floor limits are tighter than the ground-floor ones. This is how the common cases compare.
| Scheme | Permitted development? | Deciding limit | What Dorset Council checks |
|---|---|---|---|
| Two-storey rear, 3m projection, 7m+ to boundary | Often yes | 3m projection / 7m boundary | Roof match, side-window glazing |
| Two-storey rear, under 7m to boundary | No — full application | Rear-boundary distance | Overlooking, daylight, garden loss |
| Two-storey side extension | No — full application | Side elevation | Gap to boundary, street rhythm |
| Two-storey wraparound | No — full application | Combined footprint | Bulk, massing, neighbour amenity |
| Any two-storey on designated land | No — full application | Designation | Character and appearance |
Limits from the GPDO 2015, Schedule 2, Part 1, Class A — two-storey rear extension conditions.
A fixed process built around how Dorset Council validates and decides two-storey applications.
Send us your Cranborne & Alderholt postcode and garden depth. We measure the 7-metre boundary rule against your plot, confirm designation status, and score your odds against live Dorset Council decisions.
We measure the original rear wall, eaves and ridge heights, garden depth and every neighbouring window that faces the site — the inputs the daylight and overlooking case is built from.
Chartered designers develop the two-storey addition to your brief with the roof and eaves resolved, and we coordinate the load path so the structural scheme and the planning scheme are the same building.
We submit the application, manage validation and case-officer queries, and revise the drawings free until Dorset Council issues its decision.
Often, but not always. A two-storey rear extension can be permitted development if it projects no more than 3 metres, sits at least 7 metres from the rear boundary, does not exceed the existing eaves and ridge, and has obscure-glazed non-opening side windows below 1.7 metres. In Cranborne & Alderholt, the 7-metre rule is what most commonly forces a full application to Dorset Council.
No part of a permitted-development two-storey rear extension may come within 7 metres of the boundary opposite the rear wall of the house. It exists to protect the neighbour behind you from being overlooked at first floor. On shorter Cranborne & Alderholt gardens this is decisive, and we measure it on survey before any design work rather than discovering it at validation. Dorset Council is the decision-maker.
Not under permitted development — two-storey side extensions always need a full application to Dorset Council. They are assessed on the gap to the boundary, whether the street's rhythm of spaces between houses survives, and whether the extension is subordinate to the original. Setting the first floor back from the front building line and down from the ridge is what usually makes the difference. This applies to your Cranborne & Alderholt address specifically.
Overlooking is the most common objection, and it is answerable on the drawings. We position habitable-room windows away from neighbouring gardens, obscure-glaze and fix shut anything on the flank below 1.7 metres, and show the sight lines in section. Where the geometry is tight, a rooflight or a high-level window gives the same daylight without the mutual overlooking that draws objections. This applies to your Cranborne & Alderholt address specifically. Dorset Council is the decision-maker.
Almost certainly. Excavating within 3 metres of a neighbouring structure and building on or up to the boundary both trigger the Party Wall etc. Act 1996, and a two-storey extension usually does both. It is entirely separate from Dorset Council's planning decision, so we flag the notice period early and detail the junction on the drawings. This applies to your Cranborne & Alderholt address specifically.
Yes. Adding a floor changes the load path from roof to foundation, so beams, padstones and foundation depths all need designing and calculating for building control. Planning and building regulations are separate consents, and the structural set is what building control assesses — we prepare both so the approved scheme is the buildable one. This applies to your Cranborne & Alderholt address specifically. Dorset Council is the decision-maker.
We quote each Cranborne & Alderholt two-storey extension individually, because plot depth, roof form and structural complexity vary house to house, and send a fixed, no-obligation quote within one working day. It covers the drawing pack with free revisions until Dorset Council approves. Call 020 7864 7245 to start.
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