Back-of-house extension drawings for Avon Valley homes — the glazed kitchen-diner across the rear, drawn to Wiltshire Council's depth and daylight limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Wiltshire Council granted 96% of the householder planning decisions it made in its latest published year — 9 points above the 87% England-wide householder average. Avon Valley contains EAST CHISENBURY, ENFORD, FIGHELDEAN AND ABLINGTON conservation areas (EAST CHISENBURY designated 1974), 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.
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. Avon Valley carries at least one Article 4 direction, and conservation areas including EAST CHISENBURY, ENFORD and FIGHELDEAN AND ABLINGTON remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Avon Valley is determined against an 8-week statutory target.
EAST CHISENBURY (conservation area designated in 1974), ENFORD (conservation area designated in 1974), FIGHELDEAN AND ABLINGTON (designated conservation area), FITTLETON AND HAXTON (conservation area designated in 1981), NETHERAVON (conservation area designated in 1981), Milston (civil parish within Avon Valley), Netheravon (civil parish within Avon Valley), Durrington (civil parish within Avon Valley), Enford (civil parish within Avon Valley), Figheldean (civil parish within Avon Valley) and Fittleton cum Haxton (civil parish within Avon Valley) — these are the Avon Valley pockets our drawings cover most. Heritage designations here include EAST CHISENBURY, ENFORD, FIGHELDEAN AND ABLINGTON, FITTLETON AND HAXTON and NETHERAVON. Wiltshire Council weighs each proposal against Wiltshire Council's adopted local plan and its householder design guidance, where the 2,860 homes here are 27% 1955-1964, 13% pre-1900, 10% 1945-1954, which is what sets the realistic roof and rear-projection options. On roofs the borough is shallow gabled roofs typical of that period's building and steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building, over late-1950s and early-1960s houses (27% of 2,860 homes), Victorian and earlier houses (13%) and early postwar houses (10%).
Avon Valley's designated heritage is specific, and it is the first thing we check against your address: EAST CHISENBURY (conservation area designated in 1974), ENFORD (conservation area designated in 1974), FIGHELDEAN AND ABLINGTON (designated conservation area), FITTLETON AND HAXTON (conservation area designated in 1981) and NETHERAVON (conservation area designated in 1981). Inside those boundaries permitted development is curtailed and Wiltshire 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, Avon Valley takes in Milston, Netheravon, Durrington, Enford, Figheldean and Fittleton cum Haxton. Wiltshire Council has 48 recorded Article 4 directions, removing permitted development for rear and side extensions and other roof alterations, including rooflights — check the address before assuming PD applies in Avon Valley.
On stock, Avon Valley is late-1950s and early-1960s houses (27% of 2,860 homes), Victorian and earlier houses (13%) and early postwar houses (10%) — which is why shallow gabled roofs typical of that period's building and steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building govern what a loft or rear projection can realistically be. Wiltshire Council decided 1,779 householder applications in the latest published year and granted 96%, with 53% issued inside the eight-week target. Those are the numbers our drawings are prepared against.
The full build-period split for Avon Valley runs pre-1900 13% (380 homes), 1900-1918 1% (20 homes), 1919-1929 6% (170 homes), 1930-1939 8% (240 homes), 1945-1954 10% (290 homes), 1955-1964 27% (770 homes), 1965-1972 8% (230 homes), 1973-1982 6% (160 homes), 1983-1992 7% (190 homes), 1993-1999 3% (90 homes) and 2000-2008 1% (40 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.
Wiltshire Council also decides for Aldbourne & Ramsbury, Amesbury West, Box & Colerne, By Brook, Corsham Ladbrook, Corsham Pickwick, Corsham Without and Cricklade & Latton, so a decision in Avon Valley 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 Ashley, Avebury, Baydon 1 and Baydon 2. 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 Avon Valley and Wiltshire Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Avon Valley |
|---|---|
| Dwellings recorded | 2,860 |
| Built pre-1900 | 380 (13%) |
| Built 1900-1918 | 20 (1%) |
| Built 1919-1929 | 170 (6%) |
| Built 1930-1939 | 240 (8%) |
| Built 1945-1954 | 290 (10%) |
| Built 1955-1964 | 770 (27%) |
| Built 1965-1972 | 230 (8%) |
| Built 1973-1982 | 160 (6%) |
| Built 1983-1992 | 190 (7%) |
| Built 1993-1999 | 90 (3%) |
| Built 2000-2008 | 40 (1%) |
| Built before 1919 | 14% |
| Built 1919–1939 | 14% |
| Built 1945–2008 | 62% |
| Conservation areas in Avon Valley | 5 (EAST CHISENBURY, ENFORD…) |
| Conservation areas district-wide | 245 |
| Article 4 directions recorded | 48 |
| Householder applications decided | 1,779 |
| Householder applications granted | 96% |
| Decided within 8 weeks | 53% |
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 Wiltshire Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The rear extension is the workhorse of Avon Valley home improvement — it is how a dark back kitchen becomes an open family room facing the garden. Because the borough is built largely from late-1950s and early-1960s houses (27% of 2,860 homes), Victorian and earlier houses (13%) and early postwar houses (10%), most back walls sit close to a neighbour on at least one side, and that proximity, not the design, is what Wiltshire Council scrutinises. The council reads the proposal against Wiltshire Council's adopted local plan and its householder design guidance, and the first line an officer draws is the 45-degree splay from the neighbour's nearest window.
So the drawings live or die on geometry. We set the depth against the exact permitted-development figure, hold the eaves and the flat-roof or lantern build-up under the 4-metre height ceiling, and show the projection tested against both the 45-degree plan angle and the 25-degree section angle to the neighbouring windows. Avon Valley contains EAST CHISENBURY, ENFORD, FIGHELDEAN AND ABLINGTON conservation areas (EAST CHISENBURY designated 1974), so materials, fenestration and roof form are assessed against the appraisal, so the rear elevation is composed around it rather than corrected after an objection.
Where the property sits in a conservation area — EAST CHISENBURY, ENFORD, FIGHELDEAN AND ABLINGTON, FITTLETON AND HAXTON and NETHERAVON among Avon Valley's — the larger-home extension route is switched off and even a modest rear addition needs consent. Wiltshire Council has 48 recorded Article 4 directions, removing permitted development for rear and side extensions and other roof alterations, including rooflights — check the address before assuming PD applies in Avon Valley. We confirm the designation before the survey.
Many single-storey rear extensions in Avon Valley are permitted development and need no application. You will normally need to apply to Wiltshire Council, or use the larger-home prior-approval route, if any of these apply:
We draw the depth, the roof build-up and the daylight splays to each neighbour on the page — the tests Wiltshire Council's officers apply first — and submit a validation-complete pack, whether that is a lawful development certificate, a larger-home prior-approval notice or a full householder application.
Below is Wiltshire Council's real householder decision record, taken from official planning statistics and refreshed as new data lands. Wiltshire Council granted 96% of its householder applications in the year to 31 March 2026, and EAST CHISENBURY shapes what is approved here. Rear extensions turn most often on neighbour daylight and depth, so a drawing pack that proves those tests 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 EAST CHISENBURY, ENFORD and FIGHELDEAN AND ABLINGTON, the approved rear extension is typically a single-storey glazed box within the depth limit, roofed either flat with a lantern or in a shallow mono-pitch, and finished in brick or render to match the host wall. On the borough's late-1950s and early-1960s houses (27% of 2,860 homes), keeping the projection to the permitted-development figure often avoids an application entirely; where owners want the full 6 metres, the larger-home route succeeds when the neighbour-consultation period passes without a sustained objection.
The 2,860 homes here are 27% 1955-1964, 13% pre-1900, 10% 1945-1954, which is what sets the realistic roof and rear-projection options. We keep the extension inside the daylight splays, set any glazed roof below the first-floor cill, and retain the garden depth Wiltshire Council expects — so the back elevation answers the amenity case before a neighbour can lodge one. Two-storey rear extensions we draw with the 7-metre boundary gap and privacy screening resolved on the plan.
We draw rear extensions on every street in the borough. A few of the neighbourhoods where Avon Valley back-of-house projects come up most often:
Rear extension drawings for EAST CHISENBURY's conservation area designated in 1974 — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
Rear extension drawings for ENFORD's conservation area designated in 1974 — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
Rear extension drawings for FIGHELDEAN AND ABLINGTON's designated conservation area — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
Rear extension drawings for FITTLETON AND HAXTON's conservation area designated in 1981 — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
Rear extension drawings for NETHERAVON's conservation area designated in 1981 — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
Rear extension drawings for Milston's civil parish within Avon Valley — depth-checked, daylight-tested and drawn to Wiltshire Council's guidance.
How far you can extend at the back in Avon Valley depends on your house type and the route you take. This is how the options compare.
| Route | Depth allowed | Consent needed | What Wiltshire Council checks |
|---|---|---|---|
| Standard permitted development | 3m terrace/semi · 4m detached | Lawful development certificate (optional) | Depth, 4m height, materials |
| Larger-home prior approval | 6m terrace/semi · 8m detached | Prior-approval notice + neighbour consultation | Neighbour objections on amenity |
| Full householder application | Beyond the above, or two-storey | Full planning permission | Daylight (45°/25°), bulk, garden retained |
| Conservation area | Case by case | Full planning permission | Character, roof form, boundary treatment |
The larger-home route is switched off on designated land — conservation areas such as EAST CHISENBURY and ENFORD and Article 4 streets need a full application.
A fixed process built around how Wiltshire Council validates and decides rear-extension applications — most drawings are submission-ready within seven days of survey.
Send us your Avon Valley postcode and house type. We confirm your conservation and Article 4 status, how much rear-extension depth you have under permitted development, and score your odds against live Wiltshire Council decisions.
We measure the original rear wall, floor and eaves levels, side and rear boundary distances and the neighbours' window positions — the numbers the depth limit and daylight splays depend on.
Chartered designers develop the single or two-storey rear extension to your brief, drawn inside the permitted-development limits or to Wiltshire Council's extension design guidance, with the daylight angles shown.
We submit the certificate, prior-approval notice or application, handle validation and case-officer queries, and revise the drawings free until Wiltshire Council issues its decision.
Often not. 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 Avon Valley. You will need to involve Wiltshire Council for anything deeper via the larger-home route, for two-storey rear extensions, and for any rear extension in a conservation area such as EAST CHISENBURY and ENFORD, where those permitted-development rights fall away.
The larger-home extension scheme lets a single-storey rear extension reach 6 metres on a terrace or semi, or 8 metres on a detached house — double the standard allowance. It is not automatic: you submit a prior-approval notification to Wiltshire Council, neighbours are consulted, and if one objects on amenity grounds the council rules on it. It also does not apply on designated land such as Avon Valley's conservation areas.
It is the daylight test Wiltshire Council applies to protect neighbours. Drawn on plan, a line at 45 degrees from the midpoint of the neighbour's nearest ground-floor window should not be crossed by your extension; a companion 25-degree line is checked in section. If the projection breaches it, the extension is likely to be shortened or refused, so we test and prove it on the drawings before submission. This applies to your Avon Valley address specifically.
A two-storey rear extension almost always needs a full householder application to Wiltshire Council, as it sits outside permitted development on most homes. The council checks that it stays at least 7 metres from the rear boundary, does not overbear the neighbours and avoids new overlooking. We resolve the boundary gap, privacy and daylight on the plans so the application is decided on its merits. This applies to your Avon Valley address specifically.
Frequently, yes. If the rear extension involves work to a shared wall, building up to the boundary, or excavating foundations near a neighbour's structure, the Party Wall etc. Act applies and you must serve notice — this is separate from Wiltshire Council's planning decision. We flag it early and can prepare the drawings a party-wall surveyor needs alongside the planning set. This applies to your Avon Valley address specifically.
We price each Avon Valley rear extension on its own footprint and send a fixed, no-obligation quote within one working day. It covers the full drawing pack with free revisions until Wiltshire Council approves, and we confirm at the outset whether your extension is permitted development, needs prior approval, or a full application. Call 020 7864 7245 to begin.
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