Dormer, hip-to-gable and mansard loft conversion drawings for Hillingdon homes — prepared to Hillingdon Council's design guidance, delivered in days and revised free until your decision lands, with a free approval-odds score first.
Hillingdon Council granted 84% of the householder planning decisions it made in its latest published year — 3 points below the 87% England-wide householder average. A large slice of the borough sits in Green Belt to the west, where extensions face the openness test rather than ordinary householder policy, which is where a policy-literate drawing pack earns its keep. Its dominant Edwardian (1901–1910), interwar (1918–1939) 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 Hillingdon Council needs a full application. Hillingdon carries at least one Article 4 direction, and conservation areas including Old Uxbridge, Harefield Village and Ickenham Village remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Hillingdon is determined against an 8-week statutory target.
Uxbridge (the town centre with its Old Uxbridge conservation area and Edwardian terraces), Ruislip (Metro-land semis around the Ruislip Village conservation area), Ickenham (a village green surrounded by interwar suburban housing), Harefield (a rural Green Belt village of cottages and detached homes), Northwood (affluent detached and semi-detached houses on leafy plots) and Hayes (mixed interwar and postwar estates near the former industrial belt) — these are the Hillingdon pockets our drawings cover most. Heritage designations here include Old Uxbridge, Harefield Village, Ickenham Village, Ruislip Village and Eastcote. Hillingdon Council weighs each proposal against Hillingdon Local Plan and the HDAS: Residential Extensions SPD, where the design guidance polices the spacing and building line of Metro-land semis so paired houses keep their rhythm. On roofs the borough is hipped roofs on the 1930s semis and gabled roofs on the older village cottages, over interwar Metro-land semi-detached houses, Edwardian terraces around Uxbridge and West Drayton and detached houses and cottages in the rural western villages.
Hillingdon's roofs set the brief. The borough is built largely from interwar Metro-land semi-detached houses, Edwardian terraces around Uxbridge and West Drayton and detached houses and cottages in the rural western villages, and its lofts sit under hipped roofs on the 1930s semis and gabled roofs on the older village cottages — the geometry that decides whether a rear dormer, a hip-to-gable or a mansard gives you the headroom you want. Hillingdon Council assesses loft proposals against Hillingdon Local Plan and the HDAS: Residential Extensions 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 Hillingdon Council can verify them. A large slice of the borough sits in Green Belt to the west, where extensions face the openness test rather than ordinary householder policy, so we resolve it on the page rather than leave it for the case officer to raise.
Hillingdon also carries protected streets — Old Uxbridge, Harefield Village, Ickenham Village, Ruislip Village and Eastcote among them. Ruislip Village and the Harefield and Ickenham conservation areas carry tight controls, and Article 4 directions on some of these older village streets strip out the permitted-development rights suburban owners otherwise assume. We check your address against those designations before a line is drawn.
Many Hillingdon 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 Hillingdon Council if any of these apply:
We draw the roof line, the ridge height and the neighbour's daylight on the page — the relationships Hillingdon 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 Hillingdon Council's real householder decision record, pulled from official planning statistics and updated as new data lands. Hillingdon grants a fair share of householder applications, with Green Belt openness in the western villages and roof and spacing changes to interwar semis the recurring pinch points. 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 Uxbridge, Ruislip and Ickenham, 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 hipped roofs on the 1930s semis, that is usually the most efficient use of the roof; where the stock is gabled roofs on the older village cottages, a hip-to-gable followed by a rear dormer unlocks far more space, though it needs a full application.
The design guidance polices the spacing and building line of Metro-land semis so paired houses keep their rhythm. 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 Hillingdon 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 Hillingdon roofs come up most often:
Loft conversion drawings for Uxbridge's the town centre with its Old Uxbridge conservation area and Edwardian terraces — measured, volume-checked and drawn to Hillingdon Council's guidance.
Loft conversion drawings for Ruislip's Metro-land semis around the Ruislip Village conservation area — measured, volume-checked and drawn to Hillingdon Council's guidance.
Loft conversion drawings for Ickenham's a village green surrounded by interwar suburban housing — measured, volume-checked and drawn to Hillingdon Council's guidance.
Loft conversion drawings for Harefield's a rural Green Belt village of cottages and detached homes — measured, volume-checked and drawn to Hillingdon Council's guidance.
Loft conversion drawings for Northwood's affluent detached and semi-detached houses on leafy plots — measured, volume-checked and drawn to Hillingdon Council's guidance.
Loft conversion drawings for Hayes's mixed interwar and postwar estates near the former industrial belt — measured, volume-checked and drawn to Hillingdon Council's guidance.
The right loft in Hillingdon 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 Hillingdon 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 Old Uxbridge and Harefield Village and Article 4 directions can remove permitted-development rights.
A fixed process built around how Hillingdon Council validates and decides householder loft applications — most drawings are submission-ready within seven days of survey.
Tell us your Hillingdon 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 Hillingdon 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 Hillingdon Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Hillingdon 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 Hillingdon the main exceptions are hip-to-gable conversions, dormers visible from the highway, and homes in conservation areas such as Old Uxbridge and Harefield Village or on streets with an Article 4 direction. Hillingdon Council is the decision-maker.
Generally no. In conservation areas including Old Uxbridge and Harefield Village, Class B permitted-development rights for lofts are removed, so a rear dormer that would be lawful elsewhere needs a full application to Hillingdon Council. Ruislip Village and the Harefield and Ickenham conservation areas carry tight controls, and Article 4 directions on some of these older village streets strip out the permitted-development rights suburban owners otherwise assume. We check your exact address before drawing.
On hipped roofs on the 1930s semis, common across Hillingdon, a rear dormer is usually the most efficient conversion and often permitted development. Where the roof is gabled roofs on the older village cottages, 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. Hillingdon Council is the decision-maker.
A householder planning application in Hillingdon 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. Hillingdon Council is the decision-maker.
If your dormer is permitted development, a lawful development certificate from Hillingdon 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 Hillingdon project individually — a fixed, no-obligation price back within one working day. The quote covers the full drawing pack with free revisions until Hillingdon 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.