Annexe and granny-flat drawings for Cornwall homes — designed to stay ancillary to the main house rather than become a separate dwelling, drawn to Cornwall Council's policies, delivered in days and revised free until your decision.
Cornwall Council granted 97% of the householder planning decisions it made in its latest published year — 10 points above the 87% England-wide householder average. Cornwall contains BERRY TOWER, BODMIN, BODMIN, BOJEWYAN conservation areas (BERRY TOWER, BODMIN designated 1994), 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.
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 Cornwall Council needs a full application. In conservation areas such as BERRY TOWER, BODMIN, BODMIN and BOJEWYAN those rights are removed, so we confirm your exact address before a line is drawn. A validated householder application in Cornwall is determined against an 8-week statutory target.
BERRY TOWER, BODMIN (conservation area designated in 1994), BODMIN (conservation area designated in 1991), BOJEWYAN (conservation area designated in 2002), BOSCASTLE (conservation area designated in 1974), BOSCASWELL (conservation area designated in 2002), BOTALLACK & TRUTHWALL (conservation area designated in 2002), BUDE (conservation area designated in 1988), CADGWITH (conservation area designated in 1978), Bodmin St Petroc's (ward of Cornwall), Bude (ward of Cornwall), Camborne Trelowarren (ward of Cornwall), Camelford & Boscastle (ward of Cornwall), Falmouth Arwenack (ward of Cornwall), Feock & Kea (ward of Cornwall), Hayle West (ward of Cornwall) and Land's End (ward of Cornwall) — these are the Cornwall pockets our drawings cover most. Heritage designations here include BERRY TOWER, BODMIN, BODMIN, BOJEWYAN, BOSCASTLE, BOSCASWELL, BOTALLACK & TRUTHWALL, BUDE and CADGWITH. Cornwall Council weighs each proposal against Cornwall Council's development plan and the design policies it applies to householder applications, where the 83,150 homes here are 28% pre-1900, 7% 1965-1972, 6% 1973-1982, 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 shallow-pitched roofs and integral garages typical of that period's building, over Victorian and earlier houses (28% of 83,150 homes), late-1960s and early-1970s houses (7%) and 1970s and early-1980s houses (6%).
Heritage designation is the single biggest variable in Cornwall, and it is address-specific: BERRY TOWER, BODMIN (conservation area designated in 1994), BODMIN (conservation area designated in 1991), BOJEWYAN (conservation area designated in 2002), BOSCASTLE (conservation area designated in 1974), BOSCASWELL (conservation area designated in 2002), BOTALLACK & TRUTHWALL (conservation area designated in 2002), BUDE (conservation area designated in 1988) and CADGWITH (conservation area designated in 1978). Inside those boundaries permitted development is curtailed and Cornwall 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, Cornwall takes in Bodmin St Petroc's, Bude, Camborne Trelowarren, Camelford & Boscastle, Falmouth Arwenack, Feock & Kea, Hayle West and Land's End. No Article 4 direction is recorded for Cornwall Council, but the district's 8 conservation areas still limit permitted development on those streets.
On stock, Cornwall is Victorian and earlier houses (28% of 83,150 homes), late-1960s and early-1970s houses (7%) and 1970s and early-1980s houses (6%) — which is why steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and shallow-pitched roofs and integral garages typical of that period's building govern what a loft or rear projection can realistically be. Cornwall Council decided 1,863 householder applications in the latest published year and granted 97%, with 76% issued inside the eight-week target. We work from the council's own published record.
The full build-period split for Cornwall runs pre-1900 3% (190 homes), 1900-1918 0% (30 homes), 1919-1929 0% (10 homes), 1930-1939 6% (350 homes), 1945-1954 3% (170 homes), 1955-1964 30% (1,850 homes), 1965-1972 33% (1,990 homes), 1973-1982 4% (260 homes), 1983-1992 5% (310 homes), 1993-1999 4% (220 homes) and 2000-2008 3% (170 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.
Cornwall Council also decides for Bodmin St Petroc's, Bude, Camborne Trelowarren, Camelford & Boscastle, Falmouth Arwenack, Feock & Kea, Hayle West and Land's End, so a decision in Cornwall 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.
Published figures for Cornwall and Cornwall Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Cornwall |
|---|---|
| Dwellings recorded | 83,150 |
| Built pre-1900 | 190 (3%) |
| Built 1900-1918 | 30 (0%) |
| Built 1919-1929 | 10 (0%) |
| Built 1930-1939 | 350 (6%) |
| Built 1945-1954 | 170 (3%) |
| Built 1955-1964 | 1,850 (30%) |
| Built 1965-1972 | 1,990 (33%) |
| Built 1973-1982 | 260 (4%) |
| Built 1983-1992 | 310 (5%) |
| Built 1993-1999 | 220 (4%) |
| Built 2000-2008 | 170 (3%) |
| Built before 1919 | 30% |
| Built 1919–1939 | 7% |
| Built 1945–2008 | 49% |
| Conservation areas in Cornwall | 8 (BERRY TOWER, BODMIN, BODMIN…) |
| Conservation areas district-wide | 145 |
| Article 4 directions recorded | 0 |
| Householder applications decided | 1,863 |
| Householder applications granted | 97% |
| Decided within 8 weeks | 76% |
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 Cornwall Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
Councils do not decide annexes on square metres. They decide whether, once built, the accommodation forms part of one planning unit with the main house or a second one beside it. Cornwall Council looks at whether the garden is shared or divided, whether the annexe has its own street access and address, whether the occupier could live there entirely independently, and whether the two households would function as one. That is the whole case, and it is made or lost on the layout.
Cornwall is largely Victorian and earlier houses (28% of 83,150 homes), late-1960s and early-1970s houses (7%) and 1970s and early-1980s houses (6%), which shapes the realistic options: converting part of the existing house, extending it, or building a detached unit in the garden. A detached annexe can sometimes sit under Class E as an outbuilding incidental to the enjoyment of the dwellinghouse — but sleeping accommodation is generally not "incidental", so a garden annexe with a bedroom usually needs its own permission rather than relying on outbuilding rights.
In Cornwall's conservation areas — including BERRY TOWER, BODMIN and BODMIN — a garden building is also judged on its effect on the character of the area, which limits height and footprint before the use question is reached. No Article 4 direction is recorded for Cornwall Council, but the district's 8 conservation areas still limit permitted development on those streets.
An annexe almost always needs an application to Cornwall Council. Expect one where any of these apply:
We plan the annexe so its relationship to the main house is visible on the page — shared garden, connected access, a layout that reads as one household — and set out the case Cornwall Council has to test, rather than leaving the officer to assume the worst.
Below is Cornwall Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Cornwall Council granted 97% of 1,863 householder decisions in the year to 31 March 2026, 76% of them inside eight weeks. Annexe applications are decided on use as much as design, so the supporting case matters as much as the elevations.
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 BERRY TOWER, BODMIN, BODMIN and BOJEWYAN, the annexes that succeed keep one shared garden, take access past the main house rather than from the street, and are modest against the host building — single storey where the plot is overlooked, and set back from boundaries. On victorian and earlier houses (28% of 83,150 homes), converting an integral garage or a rear ground floor is often approved more readily than a detached garden unit, because the ancillary relationship is self-evident.
Cornwall contains BERRY TOWER, BODMIN, BODMIN, BOJEWYAN conservation areas (BERRY TOWER, BODMIN designated 1994), so materials, fenestration and roof form are assessed against the appraisal. Where Cornwall Council grants permission, it commonly attaches a condition tying occupation of the annexe to the main dwelling. That condition is not a problem to be avoided — it is usually the mechanism that makes approval possible, and we draft the application on that basis rather than pretending the annexe is something it is not.
We draw annexes across Cornwall. A few of the areas where multigenerational schemes come up most often:
Annexe and granny-flat drawings for BERRY TOWER, BODMIN — conservation area designated in 1994 — planned to stay ancillary and drawn to Cornwall Council's policies.
Annexe and granny-flat drawings for BODMIN — conservation area designated in 1991 — planned to stay ancillary and drawn to Cornwall Council's policies.
Annexe and granny-flat drawings for BOJEWYAN — conservation area designated in 2002 — planned to stay ancillary and drawn to Cornwall Council's policies.
Annexe and granny-flat drawings for BOSCASTLE — conservation area designated in 1974 — planned to stay ancillary and drawn to Cornwall Council's policies.
Annexe and granny-flat drawings for BOSCASWELL — conservation area designated in 2002 — planned to stay ancillary and drawn to Cornwall Council's policies.
Annexe and granny-flat drawings for BOTALLACK & TRUTHWALL — conservation area designated in 2002 — planned to stay ancillary and drawn to Cornwall Council's policies.
Three similar buildings, three different consents. This is what separates them.
| What you build | Planning status | Key test | What Cornwall Council checks |
|---|---|---|---|
| Garden room, no sleeping space | Often Class E permitted development | Incidental to the house | Height, footprint, boundary position |
| Annexe used by the household | Full application, usually with a tie condition | Ancillary use | Shared garden and access, layout |
| Self-contained unit, own access | New dwelling — full application | Separate planning unit | Policy on new homes, amenity, parking |
| Converted garage or ground floor | Often permitted, use still assessed | Whether use changes | Independence of the accommodation |
| Annexe on designated land | Full application | Designation | Character and appearance |
The ancillary/separate-dwelling distinction comes from section 55 of the Town and Country Planning Act 1990; outbuilding limits from the GPDO 2015, Schedule 2, Part 1, Class E.
A fixed process built around how Cornwall Council tests the use question as well as the design.
Tell us who the annexe is for and where it would sit on the plot. We confirm designation status and tell you honestly whether the scheme reads as ancillary or as a separate dwelling in Cornwall.
We measure the plot, the existing house and the access route, so the shared-garden and shared-access case can be drawn rather than asserted.
Chartered designers develop the annexe to your brief, with the layout, access and garden relationship arranged to support the ancillary case under Cornwall Council's policies.
We submit the application with a supporting statement on use, manage validation and case-officer queries, and revise free until Cornwall Council decides.
Almost always. Sleeping accommodation is generally not "incidental" to the enjoyment of a house, so it falls outside the outbuilding permitted-development right, and any annexe that could function independently raises a change-of-use question under section 55. In Cornwall we prepare a full application to Cornwall Council and make the ancillary case explicitly rather than hoping it is not asked.
A shared garden rather than a divided one, access through the main property rather than a separate street entrance, occupation by a member of the same household, and a physical and functional relationship with the main house. Cornwall Council weighs those together — no single feature decides it, but a separate front door and a fenced-off garden together usually settle it against you.
Yes, subject to permission. A detached garden annexe is assessed on its scale against the plot, its effect on neighbours and the character of the area, and then on the use question. Keeping it single storey, set in from boundaries and served off the shared garden gives it the best prospect in Cornwall, particularly near designated areas such as BERRY TOWER, BODMIN and BODMIN. Cornwall Council is the decision-maker.
Commonly, yes — a condition tying occupation of the annexe to the main dwelling, so it cannot be sold or let separately. That is normally what makes approval possible, because it removes the concern that a new independent home is being created without going through housing policy. The condition runs with the land, so it matters at resale, and we explain the implications before you commit. This applies to your Cornwall address specifically. Cornwall Council is the decision-maker.
Yes. A new annexe is new habitable accommodation, so structure, fire escape, insulation and ventilation all apply, and a detached annexe close to a boundary raises fire-spread requirements as well. Planning and building control are separate consents with separate submissions — we prepare both so the approved design is the one that can actually be built. This applies to your Cornwall address specifically. Cornwall Council is the decision-maker.
A householder application runs to an eight-week statutory target; where the council treats the annexe as creating a new unit it becomes a minor application with a thirteen-week target instead. Which route applies depends on how the use is characterised, which is precisely why the ancillary case is worth making properly at the outset. This applies to your Cornwall address specifically. Cornwall Council is the decision-maker.
We quote each Cornwall annexe individually, because plot, access and whether you are converting or building new all change the work, and send a fixed, no-obligation quote within one working day. It covers the full drawing pack and supporting statement, with free revisions until Cornwall Council approves. Call 020 7864 7245 to start.
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