House Extension Drawings in Mayfair W1K
Fixed-fee, MCIAT-chartered house extension drawings for Mayfair (W1K) homeowners — Westminster City Council validation and local constraints handled from the start.
Mayfair (W1K) is dense Georgian townhouse and mews fabric on the Grosvenor estate, where the residential work is overwhelmingly internal — reconfiguring principal floors, upgrading services, and forming or deepening basements — set against a backdrop of embassy and commercial use. Rear or roof extension opportunities are rare and tightly controlled, so most schemes hinge on how sensitively the interior and any subterranean space are handled.
With the whole area inside the Mayfair conservation area and so many buildings listed, the majority of projects require listed-building consent, and any basement is assessed against Westminster's restrictive subterranean policy. We map the listing grade and estate freeholder position before drawing and prepare a submission that meets Westminster City Council's conservation and validation expectations.
Planning in Mayfair (W1K): what to know before you apply
No published householder Article 4 direction is the operative constraint in W1K; instead it is dense statutory listing, the Mayfair conservation area and Westminster's basement policy. Grosvenor estate leaseholders additionally require freeholder licence for alterations, which we coordinate with the planning and listed-building applications.
Typical Mayfair housing stock
Georgian townhouses and their mews, arranged around Grosvenor Square and Mount Street on the Grosvenor estate, interleaved with red-brick and Portland-stone mansion blocks, embassies and high-value residential conversions — a large proportion of it listed.
Streets we regularly draw for in Mayfair
North Row · Dunraven Street · Great Marlborough Street · Margaret Street
What W1K is actually built of
Measured from 158 classified residential buildings in W1K, not from a description of the area.
Mayfair W1K housing mix
Residential building form across the W1K postcode district, from 158 classified buildings.
| Attached on more than one side | 93% |
|---|---|
| Attached on one side | 6% |
| Detached | 1% |
| Median building footprint | 129 m² |
| Addresses per buildingAbove about 2 means flats and maisonettes dominate | 3.84 |
| Buildings classified | 158 |
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 Mayfair (W1K) 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 Mayfair W1K — 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 works in Westminster?+
I live in a mansion block — what extra consent might I need?+
Will I need a Basement Impact Assessment in Westminster?+
How long does Westminster City Council take to decide?+
How much do planning drawings cost in Westminster?+
Get your free Mayfair planning assessment
Tell us your Mayfair (W1K) address and ambition — we'll confirm feasibility, local constraints and a fixed fee within one working day.