Dormer, hip-to-gable and mansard loft conversion drawings for Hounslow homes — prepared to Hounslow Council's design guidance, delivered in days and revised free until your decision lands, with a free approval-odds score first.
Hounslow Council granted 86% of the householder planning decisions it made in its latest published year — 1 point below the 87% England-wide householder average. Side-return and mansard schemes dominate in Chiswick, where officers weigh roof bulk against a strongly uniform terrace roofscape, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901), Edwardian (1901–1910), interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
The permitted-development ceilings are fixed: 40m³ of new roof volume for a terraced loft and 50m³ for a semi or detached house under Class B, plus a 3m single-storey rear extension on a terrace or 4m on a detached house under Class A. Hounslow carries at least one Article 4 direction, and conservation areas including Bedford Park, Old Chiswick and Strand-on-the-Green remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Hounslow is determined against an 8-week statutory target.
Chiswick (Victorian and Edwardian terraces wrapped around the Bedford Park garden suburb), Brentford (older riverside terraces alongside recent waterfront redevelopment), Isleworth (the Old Isleworth riverside conservation area and Georgian frontages), Osterley (interwar semis on the fringe of Osterley Park), Feltham (postwar and interwar suburban estates to the south-west) and Hounslow (the town centre with mixed terraces and converted flats) — these are the Hounslow pockets our drawings cover most. Heritage designations here include Bedford Park, Old Chiswick, Strand-on-the-Green, Wellesley Road and Old Isleworth. Hounslow Council weighs each proposal against Hounslow Local Plan and the Residential Extension Guidelines SPD, where the borough's western edge sits under Heathrow flight paths, so glazing, ventilation and noise mitigation surface on larger schemes. Converted terraces are common through central Chiswick and Brentford, and flats and maisonettes carry no householder permitted-development rights.. On roofs the borough is London butterfly and valley roofs on the Chiswick terraces and hipped roofs on the interwar semis, over Victorian and Edwardian terraces across Chiswick, interwar semi-detached houses around Osterley and Hounslow and converted period flats and maisonettes.
Hounslow's roofs set the brief. The borough is built largely from Victorian and Edwardian terraces across Chiswick, interwar semi-detached houses around Osterley and Hounslow and converted period flats and maisonettes, and its lofts sit under London butterfly and valley roofs on the Chiswick terraces and hipped roofs on the interwar semis — the geometry that decides whether a rear dormer, a hip-to-gable or a mansard gives you the headroom you want. Hounslow Council assesses loft proposals against Hounslow Local Plan and the Residential Extension Guidelines SPD, and its case officers read each roof against the pair next door and the wider street before they read the plans.
That makes drawing quality decisive. We measure ridge and eaves heights, roof pitch and the existing stair, calculate the added volume against the permitted-development limits exactly, and show the workings on the drawings so Hounslow Council can verify them. Side-return and mansard schemes dominate in Chiswick, where officers weigh roof bulk against a strongly uniform terrace roofscape, so we resolve it on the page rather than leave it for the case officer to raise.
Hounslow also carries protected streets — Bedford Park, Old Chiswick, Strand-on-the-Green, Wellesley Road and Old Isleworth among them. Bedford Park — the pioneering garden suburb shared with Ealing — carries a long-standing Article 4 direction, and the Chiswick and Old Isleworth conservation areas remove permitted-development rights on many of their period streets. We check your address against those designations before a line is drawn.
Many Hounslow loft conversions proceed without planning permission — a rear dormer within the permitted-development volume limits (40 cubic metres on a terrace, 50 on a semi or detached house) is usually lawful. You will normally need a full application to Hounslow Council if any of these apply:
We draw the roof line, the ridge height and the neighbour's daylight on the page — the relationships Hounslow Council's officers check first — and submit a validation-complete pack, whether that is a lawful development certificate or a full householder application.
Below is Hounslow Council's real householder decision record, pulled from official planning statistics and updated as new data lands. Hounslow grants a fair share of householder applications, with terrace roofscape in the Chiswick conservation areas the dominant constraint on loft and rear schemes. Professionally prepared loft drawings anticipate those pressure points before submission, which is why complete, policy-literate packs are decided faster and refused less often than DIY applications.
Source: MHCLG planning application statistics (householder decisions, rolling year). 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 Chiswick, Brentford and Isleworth, the recurring loft is the rear dormer — a box across the back roof slope that turns a cramped attic into a full-height double bedroom and en-suite. On London butterfly and valley roofs on the Chiswick terraces, that is usually the most efficient use of the roof; where the stock is hipped roofs on the interwar semis, a hip-to-gable followed by a rear dormer unlocks far more space, though it needs a full application.
The borough's western edge sits under Heathrow flight paths, so glazing, ventilation and noise mitigation surface on larger schemes. We draw the dormer inside the volume allowance, keep the flat-roof build-up below the ridge, and set the face back from the eaves as the rules require — so the pack answers Hounslow Council's questions before they are asked. Where permitted-development rights are exhausted or removed, we prepare a householder application composed to the borough's roof-alteration guidance instead.
We draw loft conversions on every street in the borough. A few of the neighbourhoods where Hounslow roofs come up most often:
Loft conversion drawings for Chiswick's Victorian and Edwardian terraces wrapped around the Bedford Park garden suburb — measured, volume-checked and drawn to Hounslow Council's guidance.
Loft conversion drawings for Brentford's older riverside terraces alongside recent waterfront redevelopment — measured, volume-checked and drawn to Hounslow Council's guidance.
Loft conversion drawings for Isleworth's the Old Isleworth riverside conservation area and Georgian frontages — measured, volume-checked and drawn to Hounslow Council's guidance.
Loft conversion drawings for Osterley's interwar semis on the fringe of Osterley Park — measured, volume-checked and drawn to Hounslow Council's guidance.
Loft conversion drawings for Feltham's postwar and interwar suburban estates to the south-west — measured, volume-checked and drawn to Hounslow Council's guidance.
Loft conversion drawings for Hounslow's the town centre with mixed terraces and converted flats — measured, volume-checked and drawn to Hounslow Council's guidance.
The right loft in Hounslow depends on your roof. This is how the main types compare on planning route and the space they add.
| Loft type | Permitted development? | Space & headroom | What Hounslow Council checks |
|---|---|---|---|
| Rear dormer | Usually yes, within volume limits | Full-height double room at the back | Volume, set-back from eaves, ridge height |
| Hip-to-gable | No — full application | Extends the whole side of the roof | Roof bulk and the symmetry of the pair |
| Mansard | No — full application | Maximum floor area across the roof | Street character, especially in conservation areas |
| Rooflights only | Usually yes (Class C) | Light and headroom, no extra footprint | Whether rooflights sit within the existing slope |
Route depends on your street — conservation areas such as Bedford Park and Old Chiswick and Article 4 directions can remove permitted-development rights.
A fixed process built around how Hounslow Council validates and decides householder loft applications — most drawings are submission-ready within seven days of survey.
Tell us your Hounslow postcode and roof type. We confirm your conservation and Article 4 status, how much permitted-development volume you have left, and score your odds against live Hounslow Council decisions.
We measure ridge and eaves heights, roof pitch, joist levels and the existing stair — the numbers the volume calculation and head heights depend on.
Chartered designers develop the dormer, hip-to-gable or mansard to your brief, drawn inside the Class B limits or to Hounslow Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Hounslow Council issues its decision.
Often not. A rear dormer within 40 cubic metres on a terrace, or 50 on a semi-detached or detached house, set back from the eaves and no higher than the ridge, is usually permitted development. In Hounslow the main exceptions are hip-to-gable conversions, dormers visible from the highway, and homes in conservation areas such as Bedford Park and Old Chiswick or on streets with an Article 4 direction. Hounslow Council is the decision-maker.
Generally no. In conservation areas including Bedford Park and Old Chiswick, Class B permitted-development rights for lofts are removed, so a rear dormer that would be lawful elsewhere needs a full application to Hounslow Council. Bedford Park — the pioneering garden suburb shared with Ealing — carries a long-standing Article 4 direction, and the Chiswick and Old Isleworth conservation areas remove permitted-development rights on many of their period streets. We check your exact address before drawing.
On London butterfly and valley roofs on the Chiswick terraces, common across Hounslow, a rear dormer is usually the most efficient conversion and often permitted development. Where the roof is hipped roofs on the interwar semis, a hip-to-gable followed by a rear dormer gains far more usable space but needs planning permission. Our survey confirms which your roof supports before we draw. Hounslow Council is the decision-maker.
A householder planning application in Hounslow runs to a statutory eight-week target, and a lawful development certificate to eight weeks as well, though validation can add time if the pack is incomplete. We submit validation-complete drawings and manage case-officer queries to keep the decision on track. Hounslow Council is the decision-maker.
If your dormer is permitted development, a lawful development certificate from Hounslow Council is council-stamped proof of that — worth having, because every buyer's solicitor will ask for it when you sell. We prepare and submit the certificate application with the same drawing pack.
Every roof is different, so we quote each Hounslow project individually — a fixed, no-obligation price back within one working day. The quote covers the full drawing pack with free revisions until Hounslow Council approves, and we tell you upfront whether your loft qualifies as permitted development. Call 020 7864 7245 to start.
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.