House Extension Drawings in Harrow
Fixed-fee, MCIAT-chartered house extension drawings for Harrow homeowners — London Borough of Harrow validation and local constraints handled from the start.
Harrow is Metro-land in built form: rows of interwar semi-detached and detached houses across Rayners Lane, Kenton, Stanmore and Wealdstone that lend themselves to hip-to-gable and dormer loft conversions and rear extensions. On these homes such work frequently qualifies as permitted development within the volume limits, so a full application is not always needed. The London Borough of Harrow pays close attention to preserving the rhythm and consistent 1930s building line of these suburban streets, and expects extensions to respect the established line and roof form of the neighbouring houses.
The picture changes in the borough's heritage cores. Harrow on the Hill carries a protected heritage setting and long views, and Pinner's medieval high street and Pinner Hill, along with Roxeth and Harrow Weald, are conservation areas where permitted development is often restricted and a full, context-led application is required. Harrow also applies Article 4 directions to HMO conversions in designated wards and to front-boundary and hardstanding works in some areas, so the right route depends on your exact address rather than the house type alone.
We prepare Harrow planning drawings that respect the building line and roof form the borough expects, checking permitted development eligibility for semi-detached and detached homes first and confirming it with a Lawful Development Certificate where the work qualifies. In the conservation areas we design to the character of the area — materials, proportions and rooflines — and evidence the heritage considerations so the submission stands up. The fee is fixed and agreed up front, usually around 30% below an architect's charge for the same council-accepted drawings, with free redraws until Harrow approves. Drawing to the council's validation checklist, and turning drawings around in roughly seven days, keeps most applications inside the statutory eight-week determination without a validation query.
Planning in Harrow: what to know before you apply
Harrow applies Article 4 directions to HMO conversions in designated wards and controls development within Harrow on the Hill and Pinner conservation areas. For the borough's abundant 1930s semis, hip-to-gable lofts and rear extensions frequently qualify as permitted development.
Typical Harrow housing stock
Classic Metro-land interwar semi-detached and detached houses, with the historic hilltop core of Harrow on the Hill and Pinner's medieval high street.
Areas we regularly draw for in Harrow
Harrow · Pinner · Stanmore · Wealdstone · Rayners Lane · Kenton · Hatch End
House Extension Drawings for Harrow homes: the package and the process
Every house extension drawings we prepare for a Harrow property is drawn to London Borough of Harrow’s validation standards and tuned to the local constraints above. Here is what the drawing package covers and how the process runs from first survey to approval.
A well-drawn extension adds space and value while sailing through the council; a poorly-drawn one triggers objections and refusals. DrawingsDirect draws rear, side-return, wraparound, double-storey and basement extensions for London homes — sized to your borough's tolerances, with daylight and neighbour impact considered before the planners raise them.
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.
| 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 across Harrow
House Extension Drawings in Harrow — 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 Harrow?+
What does Harrow expect for a rear extension on a 1930s semi?+
Can I extend a home in Harrow on the Hill or Pinner?+
How long does Harrow Council take to decide?+
How much do planning drawings cost in Harrow?+
Get your free Harrow planning assessment
Tell us your Harrow address and ambition — we'll confirm feasibility, local constraints and a fixed fee within one working day.