Rear garden extension behind a period house in Blackheath SE3, London Borough of Lewisham

Blackheath · SE3 · Lewisham

Double Storey Extension Drawings in Blackheath SE3

Fixed-fee, MCIAT-chartered double storey extension drawings for Blackheath (SE3) homeowners — London Borough of Lewisham validation and local constraints handled from the start.

Blackheath (SE3) is one of south-east London's most tightly protected neighbourhoods, and the residential heart of it — Blackheath Village, the station approaches and the Georgian and Victorian streets around Tranquil Vale — sits within the London Borough of Lewisham. Rear and loft projects here are worked carefully around the Blackheath conservation area, which was London's very first when it was designated in 1968.

Because the conservation area spans the Lewisham–Greenwich boundary along Shooters Hill Road and the A2, we always confirm which council a Blackheath property actually falls under before advising — some estates, including The Paragon, straddle the line but are administered by Greenwich. On the Lewisham side we design to the borough's conservation-area guidance, respecting the frontages, rooflines and mature-tree setting that give the heath its character.

Proposed floor plan

Blackheath SE3

Blackheath (SE3) — planning at a glance

Council: London Borough of Lewisham
Postcode district: SE3
Planning portal: View the Lewisham planning portal
Housing stock: Georgian terraces and villas around Blackheath Village and Tranquil Vale, grand Victorian houses on the streets rising toward the heath, and the mid-century Span estates on the Cator Estate side of the neighbourhood.
Article 4: London Borough of Lewisham does not publish its Article 4 directions to the national planning register, so permitted development rights in Blackheath (SE3) can’t be confirmed from open data alone — we check the direction schedule with the council before recommending a route, as part of the fixed fee. Lewisham does not publish its householder Article 4 directions to the national register, so permitted-development status can't be confirmed from open data — we check the position for a specific Blackheath address with the council, where the Blackheath conservation area is the defining local control.
Conservation: Blackheath
Sample streets: Tranquil Vale · Montpelier Row · Lee Road · Wemyss Road
Local constraints: The Blackheath conservation area — London's first, designated 1968 — closely controlling frontages, rooflines and materials across the village and its residential streetsThe Lewisham–Greenwich borough boundary running along Shooters Hill Road and the A2, so some estates (e.g. The Paragon) are administered on the Greenwich sideMature street trees and the open heath setting under Tree Preservation Orders, with the distinctive Span estates carrying their own coherent design character

Planning in Blackheath (SE3): what to know before you apply

Blackheath's residential streets sit within the Blackheath conservation area, so frontage alterations, roof changes and materials are closely assessed and permitted-development rights are curtailed on many houses. Lewisham does not publish its Article 4 directions to the national register, so we confirm the status for a specific address with the council. SE3 also straddles the Lewisham–Greenwich boundary, so we verify which authority a property answers to before recommending a route.

Typical Blackheath housing stock

Georgian terraces and villas around Blackheath Village and Tranquil Vale, grand Victorian houses on the streets rising toward the heath, and the mid-century Span estates on the Cator Estate side of the neighbourhood.

Streets we regularly draw for in Blackheath

Tranquil Vale · Montpelier Row · Lee Road · Wemyss Road

What SE3 is actually built of

Measured from 411 classified residential buildings in SE3, not from a description of the area.

Blackheath SE3 housing mix

Residential building form across the SE3 postcode district, from 411 classified buildings.

Attached on more than one side	43%
Attached on one side	41%
Detached	16%
Median building footprint	67 m²
Addresses per buildingAbove about 2 means flats and maisonettes dominate	2.2
Buildings classified	411

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.

Double Storey Extension Drawings for Blackheath (SE3) homes: the package and the process

At first-floor level the drawings have to answer for daylight, privacy and massing. That means proposed elevations showing every new window with its position relative to the boundary, a section taken through the extension and the neighbouring building, and a roof form drawn to sit below the existing ridge rather than compete with it.

We draw the neighbouring property alongside your own, because the officer's assessment is comparative — the effect on their windows and outlook is the test. Setting the first floor in from the boundary, and showing that set-back as a dimension, resolves most objections before consultation begins.

At first floor the boundary relationship decides everything. A detached house has room to set the addition in on both sides; a semi has one shared wall and one clear flank; a mid-terrace can usually only go to the rear, where the effect on both neighbours has to be drawn.

Do I need planning permission for a double storey extension in London?

Almost always. Permitted development rights for two-storey extensions are far more restrictive than for single-storey work, particularly on how close the new structure can come to a boundary and how closely its roof pitch and eaves height must match the existing house, so most double storey projects are drawn and submitted as full householder planning applications rather than relying on permitted development.

Where the property sits in a conservation area or is subject to an Article 4 direction, any remaining permitted development allowance for a second storey is typically removed entirely, reinforcing the need for a full application. We check your property's status and your borough's design guidance before drawing.

How do councils control the impact of a double storey extension on neighbours?

Because a second storey introduces new windows and massing at first-floor level, London boroughs apply design guidance aimed specifically at protecting neighbouring light, privacy and outlook.

The 45-degree rule, tested at neighbouring windows, to check the extension does not block an unreasonable amount of daylight
A common design expectation that a two-storey side extension is set in roughly 1 metre from the shared boundary, rather than built hard against it
A first floor commonly set back from the ground floor front elevation, so the upper storey reads as subordinate to the main house from the street
Obscure or high-level glazing on flank walls facing directly into a neighbour's garden or windows, to limit overlooking

Matching the roofline and materials

Planning officers assess a double storey extension heavily on how convincingly it reads as part of the original house rather than an addition bolted onto the side. Our drawings match ridge height, roof pitch, eaves detail and brick or render finish to the existing building wherever the design brief allows, which is consistently one of the strongest factors in securing approval without delay or redesign. Where a subtly contrasting material is proposed instead — a different brick tone, or a zinc or slate roof against a tiled original — we set it out clearly on the elevations so the design intent reads as deliberate rather than a mismatch, which is how most London boroughs prefer a genuine design statement to be presented.

Extending once vs twice: single versus double storey
Option	What it adds	Typical fee
Single-storey rear extension	A ground-floor kitchen-diner only, may qualify for permitted development	see Rear Extension Drawings, from £1,100
Double storey side or rear extension	Two rooms across two floors, usually needs full planning	Full Planning pack ~£1,600–£2,400
Double storey + Building Regulations (structural)	Combined pack including structural calculations for two-floor loads and foundations	Planning + Building Regs pack ~£2,200–£3,850
Wraparound (rear + side return)	Combines two single-storey extensions into one L-shaped ground floor	see Wraparound Extension Drawings, from £2,200

Sheet from a double storey extension drawings package drawn for a Blackheath property in SE3, showing the existing and proposed arrangement at scale — A sheet from the double storey extension drawings package we submit to London Borough of Lewisham for Blackheath (SE3) properties.

Also in Blackheath SE3

Planning Permission Planning Drawings Architectural Drawings Building Regulations Drawings Loft Conversion Drawings Double Storey Extension Drawings across Lewisham Double Storey Extension Drawings across London

FAQ

Double Storey Extension Drawings in Blackheath SE3 — FAQs

How much does a double storey extension cost to design in London?+

Double storey extension drawings start from £2,400, covering full planning permission and structural design for the additional floor. A combined planning and building regulations package with full structural calculations runs up to around £3,850, fixed and agreed upfront.

Do I need planning permission to add a second storey?+

In almost all cases, yes. Permitted development rights for two-storey extensions are much tighter than for single-storey work, particularly around boundary distance and roof matching, so we design double storey projects on the assumption a full householder planning application is required.

Will a double storey extension overlook my neighbour's garden?+

That is exactly what planning officers check, using the 45-degree daylight rule alongside boundary set-in and first-floor set-back guidance. Where a new flank window would look directly into a neighbour's garden, we typically specify obscure or high-level glazing to address it before submission rather than after an objection.

Do I need an architect for a double storey extension?+

No. DrawingsDirect is an MCIAT-chartered architectural technologist practice, producing the same council-accepted drawings and in-house structural coordination as an architect, for a fixed fee typically around 30% lower, with structural calculations for the additional floor produced by the same team rather than a separately appointed engineer.

How long does it take to get double storey extension drawings?+

Drawings are typically ready around 7 days from survey. A householder planning application then has a statutory 8-week determination period once submitted.

Do I need planning permission for a side-return extension in Lewisham?+

On the Victorian and Edwardian terraces of Brockley, Forest Hill and Hither Green a single-storey side-return or rear extension can fall within permitted development, so a full application isn't always needed. Conservation areas such as Blackheath, Brockley and Telegraph Hill restrict this. We check your street's designation first and can confirm permitted development with a Lawful Development Certificate where it qualifies.

What does Lewisham's borough-wide HMO Article 4 direction affect?+

Lewisham applies a borough-wide Article 4 direction removing permitted development rights for change of use to an HMO (C3 to C4), so a conversion to a house in multiple occupation needs a full application anywhere in the borough. It doesn't affect a standard family extension or loft, but we confirm whether it applies to your intended use before advising on a route.

Can I convert the loft on my Lewisham terrace?+

Usually, yes. The terraces of Brockley, Forest Hill and Hither Green suit hip-to-gable and dormer loft conversions, which frequently qualify as permitted development within the volume limits. Outside the conservation areas this is often the quickest route. We confirm eligibility against those limits and any designation, then produce the planning and building-regulations drawings.

How long does Lewisham Council take to decide?+

Lewisham determines most householder applications within the statutory eight-week period once validated; conservation cases can attract additional consultation. The dense terraced streets are party-wall-sensitive, so the commonest delay is a drawing query — we prepare submissions to the council's validation checklist to keep them moving.

How much do planning drawings cost in Lewisham?+

We agree a fixed fee before starting, usually around 30% below an architect's fee for the same council-accepted drawings, with free redraws until Lewisham approves. A side-return, a loft and a conservation-area scheme differ in complexity, so we quote once we understand your street and project rather than charging by the hour.

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