House Extension Drawings in Hillingdon
Fixed-fee, MCIAT-chartered house extension drawings for Hillingdon homeowners — London Borough of Hillingdon validation and local constraints handled from the start.
Hillingdon is Metro-land in built form: rows of interwar semi-detached and detached houses across Ruislip, Eastcote and Ickenham that lend themselves to hip-to-gable and dormer loft conversions and rear extensions, set against the historic timber-framed core of Ruislip Village and the Colne Valley green belt to the west. These abundant Metro-land semis often retain fuller permitted development rights than inner-London terraces, so a loft or single-storey rear frequently qualifies within the volume limits, though the right route always depends on the plot and its designation.
Unlike much of London, the London Borough of Hillingdon has no borough-wide Article 4 direction affecting typical householder permitted development. The binding constraints are different: Colne Valley green-belt policy toward the western edge and Harefield restricts scale, assessing extensions against strict limits on disproportionate additions to the original dwelling. Conservation control applies in Ruislip Village, Uxbridge (Windsor Street), Northwood, Ickenham Village, Harefield and Eastcote, where permitted development is removed. Toward the south of the borough near Heathrow, aircraft-noise considerations can influence habitable-room and glazing design and need evidencing within the application.
We prepare Hillingdon planning drawings that respect the established Metro-land building line the council expects, checking permitted development eligibility for semi-detached and detached homes first and flagging any conservation, green-belt or aircraft-noise constraint for your address. You get a fixed fee agreed up front, the same council-accepted drawings an architect would produce for usually around 30% less, a roughly seven-day drawing turnaround and free redraws until Hillingdon approves. Most householder applications are determined within the statutory eight weeks once validated, so we work to the council's validation checklist to head off the queries that cause delay.
Planning in Hillingdon: what to know before you apply
Hillingdon has no borough-wide Article 4 direction affecting typical householder permitted development; the binding constraints are Colne Valley green-belt policy to the west, conservation-area control in Ruislip, Uxbridge, Ickenham and Northwood, and aircraft-noise considerations near Heathrow to the south. The borough's abundant Metro-land semis often retain fuller permitted development rights than inner-London terraces.
Typical Hillingdon housing stock
Metro-land interwar semi-detached and detached houses across Ruislip, Eastcote and Ickenham, the historic timber-framed core of Ruislip Village, and green-belt and edge-of-London properties toward Harefield and the Colne Valley.
Areas we regularly draw for in Hillingdon
Uxbridge · Ruislip · Hayes · Hillingdon · Northwood · Ickenham · Eastcote · West Drayton
What the numbers say about Hillingdon planning decisions
These are London Borough of Hillingdon’s own reported figures, published by government rather than estimated by us. They are what we design against — a borough that refuses one householder application in five needs a different drawing package from one that refuses one in twenty.
Permitted development in Hillingdon
Larger householder extensions put to London Borough of Hillingdon under the prior-approval route, and lawful-development certificates decided, over eight quarters.
| Prior approval not requiredWent ahead without a full application | 235 |
|---|---|
| Prior approval granted | 58 |
| Prior approval refused | 23 |
| Granted where a decision was neededFrom 81 determinations | 72% |
| Building upwards, prior approval refused | 0 |
| Certificates of lawful development decided | 1,146 |
Source: Ministry of Housing, Communities and Local Government (PS1 district planning application statistics). Open Government Licence v3.0 Extracted 2026-08-16.
What removes permitted development in Hillingdon
Live entries on the national planning registers for London Borough of Hillingdon. Article 4 directions withdraw permitted development rights, so a project inside one needs a full application rather than prior approval. Revoked and expired entries are excluded.
| Article 4 directions in force | 150 |
|---|---|
| Areas they coverOne direction can cover many separate areas | 150 |
| Conservation areasPermitted development is already narrower inside one | 42 |
Source: MHCLG Planning Data Platform. Open Government Licence v3.0 Extracted 2026-08-16.
House Extension Drawings for Hillingdon homes: the package and the process
Extension drawings are read for their dimensions. The proposed plan needs depth measured from the original rear wall — not from a previous extension — eaves and ridge heights taken from existing ground level, and the distance to each boundary marked. A site plan showing how much garden remains is what an officer reaches for when the amenity question comes up.
We draw the existing building accurately first, because everything else is measured from it. Where the original footprint has already been added to, that history goes on the drawing: it decides which allowances are still available and it is the first thing an officer checks against the council's own records.
The plot decides the extension type long before taste does. A mid-terrace has depth to work with and an alley if it is lucky; a semi has one clear flank; a detached house can go wide. Reading the building form first is what stops a design being drawn that the plot cannot take.
Which extension types do you draw?
Every London extension is shaped by the plot, the neighbours and the borough's design guidance. We draw them all.
Rear extension
A single-storey rear extension is often permitted development within depth limits — ideal for an open-plan kitchen-diner.
Side-return
Fills the alley beside a Victorian terrace, widening the ground floor without losing garden.
Wraparound
Combines a rear and side-return extension for a transformative ground floor, usually needing planning permission.
Double-storey
Adds space above and below, subject to tighter scale and neighbour-impact scrutiny.
Basement
Creates space downward where footprint is limited, with structural and party-wall care.
Do I need planning permission for a house extension in London?
Single-storey rear extensions within permitted development limits (up to 6m for terraced/semi-detached homes under the larger-home scheme, subject to neighbour consultation) may not need a full application. Wraparounds, double-storeys and anything in a conservation area usually do. We assess your plot and recommend the right route before drawing. The current depth, height and eaves limits are set out in full in the guide to planning permission for a rear extension, and where you would rather one practice ran the design, the application and the building-regulations stage together, Architectural Drawings covers that full scope.
How do you maximise the footprint the council will approve?
We know each borough's depth, height and daylight standards, so we design to the edge of what will be approved rather than guessing — and we check the 45-degree neighbour daylight rule and any rear building line before submission. Where a plot is tight we test a permitted-development scheme against a slightly larger householder application and show you the trade-off in space, cost and timescale, so the drawn scheme is the one that actually maximises value rather than just floor area.
| Extension | Typical route | Package | Fee from |
|---|---|---|---|
| Single-storey rear | Permitted development / householder | Planning + building regs | £1,100 |
| Side-return | Householder planning | Planning + building regs + structural | £1,600 |
| Wraparound | Householder planning | Full package + structural | £2,200 |
| Double-storey | Householder planning | Full package + structural | £2,400 |
House Extension Drawings in Hillingdon — FAQs
How far can I extend without planning permission in London?+
Do extension drawings include structural calculations?+
How long do extension drawings take?+
Will my rear extension need a party wall agreement?+
Can I extend a house in a conservation area?+
Do I need planning permission for a loft conversion in Hillingdon?+
How does the Colne Valley green belt affect my Hillingdon project?+
Does proximity to Heathrow affect my plans?+
How long does Hillingdon Council take to decide?+
How much do planning drawings cost in Hillingdon?+
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