Side-return infill drawings for Southgate terraces — the glazed extension that fills the redundant side alley and opens up the kitchen, drawn to Crawley Borough Council's guidance, delivered in days and revised free until your decision, with a free approval-odds check first.
Crawley Borough Council granted 82% of the householder planning decisions it made in its latest published year — 5 points below the 87% England-wide householder average. Southgate contains Brighton Road Conservation Area, Malthouse Road Conservation Area, Southgate Neighbourhood Centre Conservation Area conservation areas (Brighton Road Conservation Area designated 2013), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant 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. Southgate carries at least one Article 4 direction, and conservation areas including Brighton Road Conservation Area, Malthouse Road Conservation Area and Southgate Neighbourhood Centre Conservation Area remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Southgate is determined against an 8-week statutory target.
Brighton Road (conservation area designated in 2013), Malthouse Road (conservation area designated in 2013) and Southgate Neighbourhood Centre (conservation area designated in 2013) — these are the Southgate pockets our drawings cover most. Heritage designations here include Brighton Road Conservation Area, Malthouse Road Conservation Area and Southgate Neighbourhood Centre Conservation Area. Crawley Borough Council weighs each proposal against the adopted Crawley local plan and Crawley Borough Council's design guidance for householder work, where the 3,980 homes here are 25% 1965-1972, 24% 1955-1964, 13% 1973-1982, which is what sets the realistic roof and rear-projection options. On roofs the borough is shallow-pitched roofs and integral garages typical of that period's building and shallow gabled roofs typical of that period's building, over late-1960s and early-1970s houses (25% of 3,980 homes), late-1950s and early-1960s houses (24%) and 1970s and early-1980s houses (13%).
Southgate's designated heritage is specific, and it is the first thing we check against your address: Brighton Road (conservation area designated in 2013), Malthouse Road (conservation area designated in 2013) and Southgate Neighbourhood Centre (conservation area designated in 2013). Inside those boundaries permitted development is curtailed and Crawley Borough 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.
Crawley Borough Council has 19 recorded Article 4 directions, removing permitted development for painting the exterior — check the address before assuming PD applies in Southgate.
On stock, Southgate is late-1960s and early-1970s houses (25% of 3,980 homes), late-1950s and early-1960s houses (24%) and 1970s and early-1980s houses (13%) — which is why shallow-pitched roofs and integral garages typical of that period's building and shallow gabled roofs typical of that period's building govern what a loft or rear projection can realistically be. Crawley Borough Council decided 122 householder applications in the latest published year and granted 82%, with 26% issued inside the eight-week target. Those are the numbers our drawings are prepared against.
The full build-period split for Southgate runs pre-1900 5% (210 homes), 1900-1918 3% (100 homes), 1919-1929 1% (20 homes), 1930-1939 1% (30 homes), 1945-1954 2% (80 homes), 1955-1964 24% (970 homes), 1965-1972 25% (1,010 homes), 1973-1982 13% (510 homes), 1983-1992 7% (290 homes), 1993-1999 4% (170 homes) and 2000-2008 6% (240 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.
Crawley Borough Council also decides for Northgate & West Green and Three Bridges, so a decision in Southgate 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 Aintree Road & Epsom Road, Arden Road, Ardingly Close and Beverley Mews. 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 Southgate and Crawley Borough Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Southgate |
|---|---|
| Dwellings recorded | 3,980 |
| Built pre-1900 | 210 (5%) |
| Built 1900-1918 | 100 (3%) |
| Built 1919-1929 | 20 (1%) |
| Built 1930-1939 | 30 (1%) |
| Built 1945-1954 | 80 (2%) |
| Built 1955-1964 | 970 (24%) |
| Built 1965-1972 | 1,010 (25%) |
| Built 1973-1982 | 510 (13%) |
| Built 1983-1992 | 290 (7%) |
| Built 1993-1999 | 170 (4%) |
| Built 2000-2008 | 240 (6%) |
| Built before 1919 | 8% |
| Built 1919–1939 | 1% |
| Built 1945–2008 | 82% |
| Conservation areas in Southgate | 3 (Brighton Road Conservation Area, Malthouse Road Conservation Area…) |
| Conservation areas district-wide | 13 |
| Article 4 directions recorded | 19 |
| Householder applications decided | 122 |
| Householder applications granted | 82% |
| Decided within 8 weeks | 26% |
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 Crawley Borough Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The side return is the classic terrace fix, and Southgate has the stock for it — the borough is built largely from late-1960s and early-1970s houses (25% of 3,980 homes), late-1950s and early-1960s houses (24%) and 1970s and early-1980s houses (13%), 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. Crawley Borough Council judges the infill against the adopted Crawley local plan and Crawley Borough Council's design guidance for householder work, 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. Southgate contains Brighton Road Conservation Area, Malthouse Road Conservation Area, Southgate Neighbourhood Centre Conservation Area conservation areas (Brighton Road Conservation Area designated 2013), 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 Southgate's terraces sit in conservation areas — Brighton Road Conservation Area, Malthouse Road Conservation Area and Southgate Neighbourhood Centre Conservation Area among them — where a side extension is no longer permitted development. Crawley Borough Council has 19 recorded Article 4 directions, removing permitted development for painting the exterior — check the address before assuming PD applies in Southgate. We confirm the designation before a line is drawn.
Some single-storey side returns in Southgate 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 Crawley Borough 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 Crawley Borough 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 Crawley Borough Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Crawley Borough Council granted 82% of its householder applications in the year to 31 March 2026, and Brighton Road Conservation Area shapes what is approved here. 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 Brighton Road, Malthouse Road and Southgate Neighbourhood Centre, 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 late-1960s and early-1970s houses (25% of 3,980 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 3,980 homes here are 25% 1965-1972, 24% 1955-1964, 13% 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 Crawley Borough 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 Southgate side returns come up most often:
Side return extension drawings for Brighton Road's conservation area designated in 2013 — width-checked, party-wall detailed and drawn to Crawley Borough Council's guidance.
Side return extension drawings for Malthouse Road's conservation area designated in 2013 — width-checked, party-wall detailed and drawn to Crawley Borough Council's guidance.
Side return extension drawings for Southgate Neighbourhood Centre's conservation area designated in 2013 — width-checked, party-wall detailed and drawn to Crawley Borough Council's guidance.
Whether a side return in Southgate 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 Crawley Borough 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 Brighton Road Conservation Area and Malthouse Road Conservation Area, side extensions are not permitted development and always need a full application.
A fixed process built around how Crawley Borough Council validates and decides side-return applications — most drawings are submission-ready within seven days of survey.
Send us your Southgate 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 Crawley Borough 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 Crawley Borough 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 Crawley Borough 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 Southgate you will need a full application to Crawley Borough Council for anything wider or taller, for a two-storey side return, and for any side extension in a conservation area such as Brighton Road Conservation Area and Malthouse Road Conservation Area, 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. Southgate's period terraces are ideally suited to it, which is why the side return is one of the borough's most common extensions. Crawley Borough 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 Crawley Borough 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. This applies to your Southgate address specifically.
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 Crawley Borough 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. This applies to your Southgate address specifically.
A householder planning application in Southgate 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. Crawley Borough Council is the decision-maker.
We price each Southgate 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 Crawley Borough 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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