House Extension Drawings in Isleworth TW7
Fixed-fee, MCIAT-chartered house extension drawings for Isleworth (TW7) homeowners — London Borough of Hounslow validation and local constraints handled from the start.
TW7 covers Isleworth, from the Georgian riverside huddle of Old Isleworth around the church to the leafier Victorian villa streets of Spring Grove, and most homeowners here are weighing a rear or side-return kitchen extension or a loft conversion to add space without leaving a settled address.
Because the Isleworth Riverside and Spring Grove conservation areas both sit inside the outcode, the first step is a boundary check: a scheme that is permitted development on an unprotected street can need a full householder application once you are inside the conservation area, especially for anything affecting a front or riverside elevation.
Planning in Isleworth (TW7): what to know before you apply
Most rear extensions and loft conversions outside the conservation areas proceed under permitted development, subject to size and eaves limits. Inside Isleworth Riverside or Spring Grove, or on any listed building, expect a full householder application and, for listed properties, separate listed building consent.
Typical Isleworth housing stock
The Old Isleworth riverside keeps Georgian and early-Victorian terraces and cottages around the church and Church Street, while Spring Grove and the wider TW7 streets run to substantial Victorian and Edwardian semi-detached and detached villas.
Streets we regularly draw for in Isleworth
Church Street · Lower Square · Mill Plat · North Street
What TW7 is actually built of
Measured from 412 classified residential buildings in TW7, not from a description of the area.
Isleworth TW7 housing mix
Residential building form across the TW7 postcode district, from 412 classified buildings.
| Attached on more than one side | 41% |
|---|---|
| Attached on one side | 52% |
| Detached | 7% |
| Median building footprint | 66 m² |
| Addresses per buildingAbove about 2 means flats and maisonettes dominate | 2.02 |
| Buildings classified | 412 |
Source: Ordnance Survey National Geographic Database (derived statistics). Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Extracted 2026-08-17.
House Extension Drawings for Isleworth (TW7) 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 Isleworth TW7 — 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 an extension in Hounslow?+
What extra control applies in Bedford Park?+
Does Heathrow or the river affect my Hounslow project?+
How long does Hounslow Council take to decide?+
How much do planning drawings cost in Hounslow?+
Get your free Isleworth planning assessment
Tell us your Isleworth (TW7) address and ambition — we'll confirm feasibility, local constraints and a fixed fee within one working day.