Single-storey, double-storey, rear and side extension drawings for Mullion & St Keverne homes — measured to Cornwall Council's design guidance, delivered in days and revised free until your decision, with a free approval-odds check before you commit.
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. Mullion & St Keverne contains CADGWITH, COVERACK conservation areas (CADGWITH designated 1978), 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.
Before permission is required, Class B allows 40m³ of added loft volume on a terrace and 50m³ on a semi or detached house, and Class A allows a 3m single-storey rear extension on a terrace or 4m on a detached house. In conservation areas such as CADGWITH and COVERACK those rights are removed, so we confirm your exact address before a line is drawn. A validated householder application in Mullion & St Keverne is determined against an 8-week statutory target.
CADGWITH (conservation area designated in 1978), COVERACK (conservation area designated in 1978), St. Keverne (civil parish within Mullion & St Keverne), Cury (civil parish within Mullion & St Keverne), Grade-Ruan (civil parish within Mullion & St Keverne), Gunwalloe (civil parish within Mullion & St Keverne), Landewednack (civil parish within Mullion & St Keverne) and Mullion (civil parish within Mullion & St Keverne) — these are the Mullion & St Keverne pockets our drawings cover most. Heritage designations here include CADGWITH and COVERACK. Cornwall Council weighs each proposal against Cornwall Council's development plan and the design policies it applies to householder applications, where the 3,870 homes here are 29% pre-1900, 13% 1973-1982, 10% 1965-1972, 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 trussed roofs typical of 1970s building, over Victorian and earlier houses (29% of 3,870 homes), 1970s and early-1980s houses (13%) and late-1960s and early-1970s houses (10%).
What is permitted in Mullion & St Keverne turns on designation first, so that is where we start: CADGWITH (conservation area designated in 1978) and COVERACK (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, Mullion & St Keverne takes in St. Keverne, Cury, Grade-Ruan, Gunwalloe, Landewednack and Mullion. No Article 4 direction is recorded for Cornwall Council, but Mullion & St Keverne's 2 conservation areas still limit permitted development on those streets.
On stock, Mullion & St Keverne is Victorian and earlier houses (29% of 3,870 homes), 1970s and early-1980s houses (13%) and late-1960s and early-1970s houses (10%) — which is why steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and shallow trussed roofs typical of 1970s 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 draw to that record rather than to a national average.
The full build-period split for Mullion & St Keverne runs pre-1900 29% (1,130 homes), 1900-1918 2% (60 homes), 1919-1929 4% (160 homes), 1930-1939 5% (210 homes), 1945-1954 5% (190 homes), 1955-1964 6% (220 homes), 1965-1972 10% (370 homes), 1973-1982 13% (510 homes), 1983-1992 7% (280 homes), 1993-1999 3% (110 homes) and 2000-2008 5% (210 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 Mullion & St Keverne 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 Mullion & St Keverne 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 | Mullion & St Keverne |
|---|---|
| Dwellings recorded | 3,870 |
| Built pre-1900 | 1,130 (29%) |
| Built 1900-1918 | 60 (2%) |
| Built 1919-1929 | 160 (4%) |
| Built 1930-1939 | 210 (5%) |
| Built 1945-1954 | 190 (5%) |
| Built 1955-1964 | 220 (6%) |
| Built 1965-1972 | 370 (10%) |
| Built 1973-1982 | 510 (13%) |
| Built 1983-1992 | 280 (7%) |
| Built 1993-1999 | 110 (3%) |
| Built 2000-2008 | 210 (5%) |
| Built before 1919 | 31% |
| Built 1919–1939 | 10% |
| Built 1945–2008 | 49% |
| Conservation areas in Mullion & St Keverne | 2 (CADGWITH, COVERACK) |
| 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.
Mullion & St Keverne homes come in a handful of recurring shapes, and each one points to a different extension. The borough is built largely from Victorian and earlier houses (29% of 3,870 homes), 1970s and early-1980s houses (13%) and late-1960s and early-1970s houses (10%), so a Victorian terrace usually wants a rear or side-return infill, while an interwar semi has room for a wider single-storey wrap or a two-storey side addition. Cornwall Council judges every one of them against Cornwall Council's development plan and the design policies it applies to householder applications, weighing footprint, height and the impact on the house next door before it looks at the elevations.
That is why the drawings decide the outcome. We set the extension depth against the permitted-development limits precisely, keep the eaves and ridge within the allowances, and plot the 45-degree daylight lines to the neighbours' windows so the case officer can see the amenity test is passed. Mullion & St Keverne contains CADGWITH, COVERACK conservation areas (CADGWITH designated 1978), so materials, fenestration and roof form are assessed against the appraisal, so we design around it from the first sketch rather than discover it at validation.
Mullion & St Keverne also protects whole streets — CADGWITH and COVERACK among them. No Article 4 direction is recorded for Cornwall Council, but Mullion & St Keverne's 2 conservation areas still limit permitted development on those streets. On designated land the larger-home extension route and most side extensions stop being permitted development, so we confirm your address against those layers before drawing a line.
Plenty of Mullion & St Keverne extensions are permitted development and need no planning application — a single-storey rear extension within the depth and height limits is the common case. You will normally need to apply to Cornwall Council if any of these apply:
We draw the footprint, the ridge and eaves heights and the neighbours' daylight on the page — the relationships Cornwall Council's officers weigh first — and submit a validation-complete pack, whether that is a lawful development certificate, a prior-approval notification or a full householder application.
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 its householder applications in the year to 31 March 2026, and CADGWITH shapes what is approved here. A complete, policy-literate extension pack anticipates those pressure points before submission, which is why professionally drawn applications are decided faster and refused less often than DIY ones.
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 CADGWITH, COVERACK and St. Keverne, the extension that lands most often is the single-storey rear addition — a glazed kitchen-diner across the back of the house, kept within the permitted-development depth or taken to a full application where the ground floor wants more. On the borough's victorian and earlier houses (29% of 3,870 homes), a side-return infill frequently pairs with it to square off the plan; on wider late-1960s and early-1970s houses (10%), a two-storey side or rear extension can add a bedroom above without swallowing the garden.
The 3,870 homes here are 29% pre-1900, 13% 1973-1982, 10% 1965-1972, which is what sets the realistic roof and rear-projection options. We size the extension to the amenity and daylight tests, match the roof and materials to the host house, and keep enough garden to satisfy Cornwall Council's space standards — so the scheme answers the borough's questions before an objection can raise them. Where permitted-development rights are used up or removed, we prepare the householder application to the council's extension design guidance instead.
We draw extensions on every street in the borough. A few of the neighbourhoods where Mullion & St Keverne projects come up most often:
Extension drawings for CADGWITH's conservation area designated in 1978 — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
Extension drawings for COVERACK's conservation area designated in 1978 — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
Extension drawings for St. Keverne's civil parish within Mullion & St Keverne — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
Extension drawings for Cury's civil parish within Mullion & St Keverne — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
Extension drawings for Grade-Ruan's civil parish within Mullion & St Keverne — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
Extension drawings for Gunwalloe's civil parish within Mullion & St Keverne — footprint-checked, daylight-tested and drawn to Cornwall Council's guidance.
The right extension in Mullion & St Keverne depends on your house type and how much garden you can give up. This is how the main options compare on planning route and what they add.
| Extension type | Permitted development? | What it adds | What Cornwall Council checks |
|---|---|---|---|
| Single-storey rear | Often, within 3m/4m depth (6m/8m via prior approval) | Bigger kitchen-diner across the back | Depth, height, neighbour daylight (45°) |
| Side-return infill | Sometimes, if within width and height limits | Squares off an L-shaped ground floor | Width vs the original house, glazing to boundary |
| Two-storey rear/side | No — full application | Extra bedroom or bathroom above | Bulk, overlooking, 7m rear-boundary gap |
| Wraparound (rear + side) | No — full application | Whole-width open-plan ground floor | Combined footprint and garden retained |
Route depends on your street — conservation areas such as CADGWITH and COVERACK and Article 4 directions can remove permitted-development rights.
A fixed process built around how Cornwall Council validates and decides householder extension applications — most drawings are submission-ready within seven days of survey.
Tell us your Mullion & St Keverne postcode and house type. We confirm your conservation and Article 4 status, how much permitted-development depth you have left, and score your odds against live Cornwall Council decisions.
We measure the existing footprint, floor and eaves levels, boundary distances and the neighbours' window positions — the numbers the depth limits and daylight tests depend on.
Chartered designers develop the single-storey, two-storey or side extension to your brief, drawn inside the permitted-development limits or to Cornwall Council's extension design guidance.
We submit the certificate, prior-approval notice or application, manage validation and case-officer queries, and revise the drawings free until Cornwall Council issues its decision.
Not always. A single-storey rear extension up to 3 metres deep on a terrace or semi, or 4 metres on a detached house, and no higher than 4 metres, is usually permitted development. In Mullion & St Keverne you will need to apply to Cornwall Council for two-storey extensions, side extensions wider than half the house, anything forward of the front wall, deeper rear extensions under the larger-home prior-approval route, and any extension in a conservation area such as CADGWITH and COVERACK.
Standard permitted development allows 3 metres on a terraced or semi-detached house and 4 metres on a detached one. The larger-home extension scheme can double that to 6 or 8 metres, but it needs a prior-approval notification to Cornwall Council and a neighbour-consultation period, and it does not apply on designated land such as Mullion & St Keverne's conservation areas. We confirm which route your property qualifies for before drawing.
Two-storey and double-storey extensions almost always need a full householder application to Cornwall Council, because they fall outside permitted development on most homes. The council looks closely at bulk, overlooking of neighbours and the 7-metre gap a two-storey rear extension must keep from the rear boundary. We design to those tests and show the daylight and privacy angles on the drawings. This applies to your Mullion & St Keverne address specifically.
A householder planning application in Mullion & St Keverne runs to a statutory eight-week target, a larger-home prior-approval notification to around six weeks including the neighbour-consultation period, and a lawful development certificate to eight weeks. Incomplete submissions stall at validation, so we submit a complete pack and manage officer queries to keep the decision on schedule. Cornwall Council is the decision-maker.
Yes — planning permission and building regulations are separate consents, and almost every extension needs both. Planning governs whether you can build it; building control governs how it is built, covering structure, insulation, drainage and fire safety. We prepare the building-regulations drawings alongside the planning set so Cornwall Council's building control or an approved inspector can sign the work off. This applies to your Mullion & St Keverne address specifically.
Every house and brief is different, so we price each Mullion & St Keverne extension individually and send a fixed, no-obligation quote back within one working day. It covers the full drawing pack with free revisions until Cornwall Council approves, and we tell you upfront whether your extension qualifies as permitted development. Call 020 7864 7245 to get started.
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.