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Free 2026 London Planning Report — Side Return Extension Drawings in Sidcup DA15

Kitchen extension interior in a 1930s Sidcup DA15 semi, London Borough of Bexley
Sidcup · DA15 · Bexley

Side Return Extension Drawings in Sidcup DA15

Fixed-fee, MCIAT-chartered side return extension drawings for Sidcup (DA15) homeowners — London Borough of Bexley validation and local constraints handled from the start.

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Sidcup's DA15 stretches north and west from the town toward Blackfen, Lamorbey and Longlands, mixing broad inter-war suburban avenues with older hamlets along Halfway Street and Burnt Oak Lane. Side-return, rear and loft extensions on the 1930s semis are the everyday work, but two designated conservation areas change the rules on specific streets.

The Halfway Street Conservation Area, designated in 1985, protects some of the oldest cottages in the borough around Holy Trinity Church, while the Longlands Road Conservation Area of 1992 guards an almost unaltered inter-war estate. Both carry Article 4 Directions, so alterations that are automatic elsewhere in DA15 need a full application within their boundaries.

Kitchen extension interior in a 1930s Sidcup DA15 semi, London Borough of Bexley
Isometric illustration of a Sidcup DA15 home side return extension drawings design
Proposed floor plan
Sidcup DA15

Planning in Sidcup (DA15): what to know before you apply

Within the Halfway Street and Longlands Road conservation areas the Article 4 Directions withdraw permitted development for elevation, roof, window and front-boundary changes, so alterations that are automatic on nearby 1930s streets need a householder application here. Elsewhere in DA15 — the wider Blackfen, Lamorbey and Longlands suburbs — rear and loft extensions on the inter-war semis commonly remain permitted development, subject to the usual size and height limits.

Typical Sidcup housing stock

Sidcup's DA15 stock runs from some of the oldest houses in the borough — the 17th- and 18th-century cottages lining Halfway Street and Burnt Oak Lane — to the almost unaltered inter-war semi-detached estate of Longlands Road, with broad Edwardian and 1930s suburban avenues around Blackfen and Lamorbey in between.

Streets we regularly draw for in Sidcup

Halfway Street · Burnt Oak Lane · Longlands Road · Blackfen Road

Side Return Extension Drawings for Sidcup (DA15) homes: the package and the process

Every side return extension drawings we prepare for an Sidcup property is drawn to London Borough of Bexley’s validation standards and tuned to the DA15 constraints above. Here is what the drawing package covers and how the process runs from first survey to approval.

Behind most London terraces sits a narrow side alley, a metre or so wide, running from the front boundary to the back garden. A side return extension builds into that alley at ground floor, pushing the kitchen wall out to line up with the rest of the house and topping the new space with a glazed or pitched roof — often the single biggest transformation available to a galley kitchen without touching the garden at all. Because the alley typically sits hard against next door's boundary wall, this is also the extension type most likely to involve your neighbour directly, both through the planning application and through the Party Wall process.

DrawingsDirect draws side return extensions for full planning, coordinates the Party Wall paperwork your neighbour will need to see, and produces the structural calculations for the beam that carries the new roof, all under one MCIAT-chartered team and one fixed fee. If you are also extending the rear at the same time, our Wraparound Extension page covers the combined project.

Do I need planning permission for a side return extension in London?

Permitted development rights for side extensions are narrower than for rear extensions: they generally cap the extension at a single storey, restrict its width to no more than half the width of the original house, and limit its height. In practice, a full-depth side return running the length of a Victorian or Edwardian terrace usually exceeds one or more of these limits, so most side return projects are drawn and submitted as a full householder planning application.

Conservation area status and Article 4 directions, common across inner London terraces, remove permitted development rights for side extensions entirely in many streets, reinforcing the need for a planning application. We check your property's status before drawing.

What does a side return extension involve?

A side return infills the alley at ground floor level, structurally opening the original flank wall of the kitchen into the new space so the two areas read as one room. Unlike a rear extension, which is bounded on three sides by your own garden, a side return is bounded on one long side by the neighbouring property, which shapes almost every decision in the design, from where the roof glazing sits to how deep the new foundations need to go.

  • New flank wall built out to align with the rear of the house, following the boundary line
  • Original external wall between kitchen and alley opened up and supported on a steel or glulam beam
  • Roof over the new space either glazed in full, glazed in a strip along the boundary for a 'light well' effect, or pitched and tiled to match the main roof
  • Kitchen re-planned across the combined footprint, often incorporating an island once the room widens
Side return project options
PackageWhat it coversTypical fee
Side return, planning onlyFull householder planning application drawings for the infillFull Planning pack ~£1,600–£2,400
Side return, planning + Building RegulationsAdds structural calculations, Party Wall drawings and construction detailPlanning + Building Regs pack ~£2,200–£3,850
Side return + rear extension (wraparound)Combines both extensions into one L-shaped ground floorsee Wraparound Extension Drawings
Measured survey onlyA measured existing floor-plan set for your own architect, surveyor or builderfrom £450

Also in Sidcup DA15

Planning PermissionPlanning DrawingsArchitectural DrawingsBuilding Regulations DrawingsLoft Conversion DrawingsSide Return Extension Drawings across BexleySide Return Extension Drawings across London
FAQ

Side Return Extension Drawings in Sidcup DA15 — FAQs

How much does a side return extension cost to design in London?+
Side return drawings start from £1,400. The final fee depends on whether you commission planning drawings alone or a combined planning and building regulations package with structural calculations, all fixed and agreed upfront.
Can I build a side return under permitted development?+
Rarely for a full-width, full-depth side return. Permitted development for side extensions is limited on width and storeys, and most Victorian and Edwardian terraces sit in conservation areas that remove these rights anyway, so a full planning application is the usual route. We still check your specific property first, since some semi-detached and detached houses outside conservation areas retain more generous side-extension allowances.
When do I need to serve Party Wall notice on my neighbour?+
Before work starts, and ideally once your drawings and structural design are settled, since the notice needs accurate dimensions. We can prepare the supporting drawings alongside your planning application so both processes run in parallel.
Do I need an architect for a side return extension?+
No. DrawingsDirect is an MCIAT-chartered architectural technologist practice, so you get the same council-accepted drawings as an architect, for a fixed fee typically around 30% lower, with structural calculations produced in-house.
How long does a side return extension take to design and approve?+
Drawings are typically ready around 7 days from survey. A householder planning application then has a statutory 8-week determination period, running alongside your Party Wall notice period.
Do I need planning permission for an extension in Bexley?+
Bexley has no borough-wide Article 4 direction affecting typical householder permitted development, so its semi-detached homes often keep fuller rights than inner-London terraces — larger rear and single-storey extensions can qualify. Conservation areas such as Old Bexley Village and Danson Park, and riverside flood-zone constraints toward Erith, restrict this. We check your address first and can confirm permitted development with a Lawful Development Certificate.
Can I build a bigger extension because Bexley plots are larger?+
Often, yes. The generous interwar plots across Bexleyheath, Sidcup and Welling make substantial rear and double-storey extensions viable where a tight terrace could not. The limit is usually design and amenity policy rather than space. We design to use the plot fully within permitted-development allowances or a well-evidenced full application.
What extra control applies in Old Bexley Village or around Danson Park?+
These conservation areas carry design control over materials, rooflines and front elevations, and the Upton area of Bexleyheath includes the setting of William Morris's Red House. Permitted development is often restricted there, so we design to the area's character and prepare a full, context-led application where a standard permitted-development route doesn't apply.
How long does Bexley Council take to decide?+
Bexley determines most householder applications within the statutory eight-week period once validated; conservation cases can involve additional consultation. A complete, correctly scaled submission is the best way to avoid a validation query — we prepare Bexley drawings to the council's checklist to keep the application on track.
How much do planning drawings cost in Bexley?+
We quote a fixed fee upfront, typically around 30% below an architect's charge for the same council-accepted drawings, with free redraws until Bexley approves. Because plots here allow larger schemes, the fee tracks complexity — a single-storey rear differs from a double-storey — and we confirm it once we understand your plans.
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