Rear dormer drawings for Longwell Green roofs — the box across the back slope that turns a low attic into a full-height room, drawn to South Gloucestershire Council's guidance and the volume limits, delivered in days and revised free until your decision, with a free approval-odds check first.
South Gloucestershire Council granted 83% of the householder planning decisions it made in its latest published year — 4 points below the 87% England-wide householder average. Longwell Green contains the Hanham Abbots Conservation Area conservation area (Hanham Abbots Conservation Area designated 1989), 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. Longwell Green carries at least one Article 4 direction, and conservation areas including Hanham Abbots Conservation Area remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Longwell Green is determined against an 8-week statutory target.
Hanham Abbots (conservation area designated in 1989), Hanham Abbots (civil parish within Longwell Green) and Oldland (civil parish within Longwell Green) — these are the Longwell Green pockets our drawings cover most. Heritage designations here include Hanham Abbots Conservation Area. South Gloucestershire Council weighs each proposal against South Gloucestershire Council's development plan and the design policies it applies to householder applications, where the 3,980 homes here are 32% 1973-1982, 27% 1955-1964, 21% 1983-1992, which is what sets the realistic roof and rear-projection options. On roofs the borough is shallow trussed roofs typical of 1970s building and shallow gabled roofs typical of that period's building, over 1970s and early-1980s houses (32% of 3,980 homes), late-1950s and early-1960s houses (27%) and 1980s estate houses (21%).
Longwell Green's designated heritage is specific, and it is the first thing we check against your address: Hanham Abbots (conservation area designated in 1989). Inside those boundaries permitted development is curtailed and South Gloucestershire 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, Longwell Green takes in Hanham Abbots and Oldland. South Gloucestershire Council has 2 recorded Article 4 directions — check the address before assuming PD applies in Longwell Green.
On stock, Longwell Green is 1970s and early-1980s houses (32% of 3,980 homes), late-1950s and early-1960s houses (27%) and 1980s estate houses (21%) — which is why shallow trussed roofs typical of 1970s building and shallow gabled roofs typical of that period's building govern what a loft or rear projection can realistically be. South Gloucestershire Council decided 771 householder applications in the latest published year and granted 83%, with 61% issued inside the eight-week target. Those are the numbers our drawings are prepared against.
The full build-period split for Longwell Green runs pre-1900 2% (90 homes), 1900-1918 1% (20 homes), 1919-1929 1% (40 homes), 1930-1939 2% (80 homes), 1945-1954 2% (70 homes), 1955-1964 27% (1,060 homes), 1965-1972 3% (110 homes), 1973-1982 32% (1,290 homes), 1983-1992 21% (850 homes), 1993-1999 1% (50 homes) and 2000-2008 3% (100 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.
South Gloucestershire Council also decides for Boyd Valley, Frampton Cotterell, Frenchay & Downend, Parkwall & Warmley, Severn Vale and Winterbourne, so a decision in Longwell Green 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 Land at Gloucester Road North in the Filton ward and Land at Stoke Park and Cheswick ward East of Southmead Road. 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 Longwell Green and South Gloucestershire Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Longwell Green |
|---|---|
| Dwellings recorded | 3,980 |
| Built pre-1900 | 90 (2%) |
| Built 1900-1918 | 20 (1%) |
| Built 1919-1929 | 40 (1%) |
| Built 1930-1939 | 80 (2%) |
| Built 1945-1954 | 70 (2%) |
| Built 1955-1964 | 1,060 (27%) |
| Built 1965-1972 | 110 (3%) |
| Built 1973-1982 | 1,290 (32%) |
| Built 1983-1992 | 850 (21%) |
| Built 1993-1999 | 50 (1%) |
| Built 2000-2008 | 100 (3%) |
| Built before 1919 | 3% |
| Built 1919–1939 | 3% |
| Built 1945–2008 | 89% |
| Conservation areas in Longwell Green | 1 (Hanham Abbots Conservation Area) |
| Conservation areas district-wide | 30 |
| Article 4 directions recorded | 2 |
| Householder applications decided | 771 |
| Householder applications granted | 83% |
| Decided within 8 weeks | 61% |
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 South Gloucestershire Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
The box dormer is the workhorse loft, and most of Longwell Green is built for it — the borough runs to 1970s and early-1980s houses (32% of 3,980 homes), late-1950s and early-1960s houses (27%) and 1980s estate houses (21%) under shallow trussed roofs typical of 1970s building and shallow gabled roofs typical of that period's building, and a flat-roofed box across the rear slope is the cheapest cubic metre of full-height space those roofs give up. South Gloucestershire Council tests the dormer against South Gloucestershire Council's development plan and the design policies it applies to householder applications, and because permitted development turns on a number, the volume you propose against the volume you have left is the first thing an officer or a certificate checks.
That is why the arithmetic goes on the drawings. We calculate the box against the 40- or 50-cubic-metre allowance, count any earlier roof enlargement into the total, hold the flat roof below the ridge and set the face back off the eaves so the dormer reads as subordinate. Longwell Green contains the Hanham Abbots Conservation Area conservation area (Hanham Abbots Conservation Area designated 1989), so materials, fenestration and roof form are assessed against the appraisal, so the cheeks, the window line and the material are drawn to answer it rather than invite a query.
Where Longwell Green's streets are protected — Hanham Abbots Conservation Area among them — the Class B dormer right is switched off and even a modest rear box needs consent. South Gloucestershire Council has 2 recorded Article 4 directions — check the address before assuming PD applies in Longwell Green. We confirm the designation before the box is sized.
Many rear dormers in Longwell Green are permitted development, but the volume and position decide it. You will normally need a full application to South Gloucestershire Council if any of these apply:
We draw the box within its volume allowance, the flat roof below the ridge and the face set back off the eaves — the three things a dormer stands or falls on — and submit a validation-complete pack, whether that is a lawful development certificate or a full householder application.
Below is South Gloucestershire Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. South Gloucestershire Council granted 83% of its householder applications in the year to 31 March 2026, and Hanham Abbots Conservation Area shapes what is approved here. A dormer is decided on volume and set-back, so a pack that shows the calculation and the eaves detail is cleared 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 Hanham Abbots, Hanham Abbots and Oldland, the dormer that goes through is the subordinate rear box: flat roof kept low, cheeks clad to recede, side windows obscure-glazed against overlooking, and the whole thing set back so the original eaves line still reads from the garden. On shallow trussed roofs typical of 1970s building, this returns a full-height double and en-suite from what was standing-room-only, usually inside the permitted-development volume.
The 3,980 homes here are 32% 1973-1982, 27% 1955-1964, 21% 1983-1992, which is what sets the realistic roof and rear-projection options. We keep the box off the ridge, match the cheek material to the roof, and where the volume is already spent — or the street is designated — draw the dormer as a householder application composed to South Gloucestershire Council's roof-alteration guidance rather than push a certificate that would be refused.
We draw rear dormers on the terraced and semi-detached streets across the borough. A few of the neighbourhoods where Longwell Green dormers come up most often:
Dormer loft drawings for Hanham Abbots's conservation area designated in 1989 — volume-checked, set-back-detailed and drawn to South Gloucestershire Council's guidance.
Dormer loft drawings for Hanham Abbots's civil parish within Longwell Green — volume-checked, set-back-detailed and drawn to South Gloucestershire Council's guidance.
Dormer loft drawings for Oldland's civil parish within Longwell Green — volume-checked, set-back-detailed and drawn to South Gloucestershire Council's guidance.
Whether a dormer in Longwell Green needs permission comes down to where it sits and how big the box is. This is how the cases compare.
| Dormer type | Permitted development? | What it gains | What South Gloucestershire Council checks |
|---|---|---|---|
| Rear box, within volume | Usually yes | Full-height room across the back | Volume total, 20cm eaves set-back |
| Rear box, over volume limit | No — full application | A larger room | How far over the allowance, bulk |
| Front or side dormer | No — full application | Light to the front rooms | Visibility from the street, character |
| Dormer in a conservation area | No — full application | Same space, extra scrutiny | Roof form and street appearance |
In conservation areas such as Hanham Abbots Conservation Area, Class B dormer rights are removed and every dormer needs a full application.
A fixed process built around how South Gloucestershire Council validates and decides dormer applications — most drawings are submission-ready within seven days of survey.
Send us your Longwell Green postcode and roof type. We confirm your conservation and Article 4 status, work out how much permitted-development volume you have left, and score your odds against live South Gloucestershire Council decisions.
We measure ridge and eaves heights, roof pitch and the existing loft floor — the numbers the volume calculation, the set-back and the head heights depend on.
Chartered designers develop the box to your brief, drawn inside the Class B volume limits or, where those are exhausted or removed, to South Gloucestershire Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until South Gloucestershire Council issues its decision.
Often not. A rear box dormer within 40 cubic metres on a terrace, or 50 on a semi or detached house, set back at least 20 centimetres from the eaves and kept below the ridge, is usually permitted development. In Longwell Green you will need a full application to South Gloucestershire Council for a front or side dormer, a box that exceeds the volume, and any dormer in a conservation area such as Hanham Abbots Conservation Area, where those rights are removed.
The permitted-development limit is a volume, not a footprint: 40 cubic metres of added roof space on a terraced house and 50 on a semi-detached or detached one, and any earlier loft enlargement counts against that total. In Longwell Green the box must also sit below the ridge and back from the eaves. We measure your roof and calculate the exact volume you have left before drawing. South Gloucestershire Council is the decision-maker.
Not under permitted development. A dormer on the front roof slope, or one facing a highway, always needs a full application to South Gloucestershire Council, because it changes how the house reads from the street. Rear box dormers are far more likely to be approved — or to be permitted development outright — which is why almost every Longwell Green dormer we draw sits on the back slope.
Often, on a terrace or semi. If the dormer or the loft steelwork meets the party wall with your neighbour, the Party Wall etc. Act applies and notice must be served before work starts — separately from South Gloucestershire Council's planning decision. We flag the party-wall junction on the drawings so a surveyor can be appointed early and the build is not held up. This applies to your Longwell Green address specifically.
If your dormer is permitted development, a lawful development certificate from South Gloucestershire Council is council-stamped proof of it — worth holding, because a buyer's solicitor will ask for it when you sell. We prepare and submit the certificate with the same measured drawing pack that shows the box within its volume allowance. This applies to your Longwell Green address specifically.
We price each Longwell Green dormer individually, because the roof pitch and the volume left 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 South Gloucestershire Council approves, and we confirm at the outset whether your box is permitted development or needs an application. Call 020 7864 7245 to start.
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