Side-return infill drawings for Cornwall terraces — the glazed extension that fills the redundant side alley and opens up the kitchen, drawn to Cornwall Council's guidance, delivered in days and revised free until your decision, with a free approval-odds check first.
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.
The side return is the classic terrace fix, and Cornwall has the stock for it — the borough is built largely from Victorian and earlier houses (28% of 83,150 homes), late-1960s and early-1970s houses (7%) and 1970s and early-1980s houses (6%), and the Victorian and Edwardian versions almost all have an L-shaped back addition with a wasted alley beside it. Fill that alley and the dark galley kitchen becomes a bright, square room the full width of the house. Cornwall Council judges the infill against Cornwall Council's development plan and the design policies it applies to householder applications, and because it runs along the party boundary, the neighbour relationship is read before the design.
That boundary is where the drawings earn their keep. We set the infill wall on or up to the line, keep the roof — usually a glazed lantern or a shallow pitch tying into the existing back-addition slope — below the neighbour's first-floor windows, and detail the rainwater and party-wall junction so the build is watertight and the Party Wall Act is satisfied. 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, so we resolve it on the section rather than leave it to the case officer.
Many of Cornwall's terraces sit in conservation areas — BERRY TOWER, BODMIN, BODMIN, BOJEWYAN, BOSCASTLE, BOSCASWELL, BOTALLACK & TRUTHWALL, BUDE and CADGWITH among them — where a side extension is no longer permitted development. No Article 4 direction is recorded for Cornwall Council, but the district's 8 conservation areas still limit permitted development on those streets. We confirm the designation before a line is drawn.
Some single-storey side returns in Cornwall are permitted development, but the width and boundary make an application more likely than for a straight rear extension. You will normally need to apply to Cornwall Council if any of these apply:
We draw the infill wall on the boundary, the glazed roof below the neighbour's windows and the party-wall junction on the page — the details Cornwall Council's officers and your neighbour both check — and submit a validation-complete pack, whether that is a lawful development certificate 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 1,863 householder decisions in the year to 31 March 2026, 76% of them inside eight weeks. Side returns hinge on width, roof glazing and the party boundary, so a pack that resolves those details upfront is decided 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 BERRY TOWER, BODMIN, BODMIN and BOJEWYAN, the approved side return is a single-storey infill roofed with a glazed lantern or roof light to pull daylight deep into the plan, its flank wall built on the boundary and finished to match the host brick. On the borough's victorian and earlier houses (28% of 83,150 homes), this is frequently the single biggest gain in usable ground-floor space, and where it stays within the width and height limits it can proceed under permitted development or a lawful development certificate.
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. We keep the glazed roof below the neighbour's cill line, set the gutter and the party-wall flashing so water and maintenance are designed in, and — where owners want the full open-plan room — pair the infill with a rear extension as a single wraparound application. That way Cornwall Council sees one coherent scheme rather than two overlapping ones.
We draw side-return infills on every terraced street in the borough. A few of the neighbourhoods where Cornwall side returns come up most often:
Side return extension drawings for BERRY TOWER, BODMIN's conservation area designated in 1994 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Side return extension drawings for BODMIN's conservation area designated in 1991 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Side return extension drawings for BOJEWYAN's conservation area designated in 2002 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Side return extension drawings for BOSCASTLE's conservation area designated in 1974 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Side return extension drawings for BOSCASWELL's conservation area designated in 2002 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Side return extension drawings for BOTALLACK & TRUTHWALL's conservation area designated in 2002 — width-checked, party-wall detailed and drawn to Cornwall Council's guidance.
Whether a side return in Cornwall needs permission comes down to width, storeys and whether the street is designated. This is how the cases compare.
| Side return type | Permitted development? | What it gains | What Cornwall Council checks |
|---|---|---|---|
| Single-storey infill, within limits | Often yes, if under half the house width | Full-width kitchen-diner | Width, 4m height, roof glazing |
| Single-storey, over half width | No — full application | Wider room, more light | Boundary treatment, neighbour amenity |
| Two-storey side return | No — full application | Room above as well as below | Bulk, overlooking, terrace rhythm |
| Wraparound (side + rear) | No — full application | L-shaped open-plan ground floor | Combined footprint, garden retained |
In conservation areas such as BERRY TOWER, BODMIN and BODMIN, side extensions are not permitted development and always need a full application.
A fixed process built around how Cornwall Council validates and decides side-return applications — most drawings are submission-ready within seven days of survey.
Send us your Cornwall postcode and terrace type. We confirm your conservation and Article 4 status, whether the infill stays within the side-extension width limit, and score your odds against live Cornwall Council decisions.
We measure the side alley, the back-addition wall, floor and eaves levels and the neighbour's window heights — the numbers the width limit, roof pitch and party-wall detailing depend on.
Chartered designers develop the infill and its glazed roof to your brief, drawn inside the permitted-development limits or to Cornwall Council's extension guidance, with the boundary and party-wall junction detailed.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Cornwall Council issues its decision.
Sometimes not. A single-storey side-return infill can be permitted development if it is no wider than half the original house, no higher than 4 metres, and the property is not on designated land. In Cornwall you will need a full application to Cornwall Council for anything wider or taller, for a two-storey side return, and for any side extension in a conservation area such as BERRY TOWER, BODMIN and BODMIN, where those rights are removed.
It is an infill that fills the narrow open alley running alongside the rear back-addition of a Victorian or Edwardian terrace — the strip of ground that is usually too small to use. Building over it squares off the ground floor, so a cramped galley kitchen becomes a full-width room. Cornwall's period terraces are ideally suited to it, which is why the side return is one of the borough's most common extensions. Cornwall Council is the decision-maker.
Almost always. A side return is built on or up to the boundary with your neighbour, so the Party Wall etc. Act applies and you must serve notice before work starts — this is entirely separate from Cornwall Council's planning decision. We detail the party-wall junction on the drawings and flag the notice early so a surveyor can be appointed without delaying the build.
Yes, and it is common — the combined L-shape is a wraparound extension. Once the side infill joins a rear projection beyond the permitted-development depth, the whole thing needs a full householder application to Cornwall Council rather than qualifying as permitted development. We draw it as one coherent scheme so the council assesses a single footprint, which reads more clearly than two overlapping proposals.
A householder planning application in Cornwall runs to a statutory eight-week target, and a lawful development certificate to eight weeks as well, though an incomplete pack can stall at validation. Because a side return involves the boundary and roof glazing, a complete, well-detailed submission matters — we prepare it validation-complete and manage officer queries to keep the decision on track. Cornwall Council is the decision-maker.
We price each Cornwall side return individually, because alley width and roof form 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 Cornwall Council approves, and we confirm at the outset whether your infill is permitted development or needs an application. Call 020 7864 7245 to start.
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