Planning · Extensions · Process
Side Return Extension Process in London
The real sequence for Victorian closet-wing infills — geometry, neighbours, drains and consents — not just a glass roof mood board.
Why side returns are a systems project
A side return fills the narrow strip beside a Victorian or Edwardian closet wing. The room only works if planning envelope, steel openings, drainage, party walls and roof glazing are designed as one system. This guide sets out that process for London terraces.
Our fixed-fee packages
Design fees, inc. VAT — separate from the council fees above
| Package | Fixed fee |
|---|---|
| Planning Route ReviewA paid route check before drawings or applications. | £395 inc. VAT |
| Standard Planning Drawings PackageFor straightforward householder schemes. | from £1,450–£1,950 inc. VAT |
| Full Householder Planning PackageDrawings plus application preparation and submission. | from £2,250–£3,250 inc. VAT |
| Licence to Alter / Flat Refurbishment Drawing PackLeasehold flat alterations and freeholder consent drawings. | from £1,500–£2,750 inc. VAT |
| Building Regulations / Technical Drawing PackageTechnical drawings once the planning route is clear. | from £2,750–£4,950 inc. VAT |
| Listed / Conservation Planning PackHeritage-led drawings and consent strategy. | Quoted after review |
Fixed fees quoted before you commit, credited from the £395 route review if you proceed. Larger, listed or complex projects are quoted after a paid review rather than sold at a fixed price. See all packages or find your package.
1. Measure the wing and the flank
Survey existing closet-wing width, party wall positions, drain runs and neighbour windows. Plan-only “infill” sketches fail when the flank height or drain position was never measured.
2. Confirm PD vs planning
Some single-storey side returns on unrestricted houses can fall under permitted development; conservation areas, Article 4 directions and flats often force a householder application. Confirm for the pin — see side return extensions overview and Camden / H&F process hubs for local controls.
3. Design amenity and structure together
Neighbour daylight and outlook set depth and height. Opening the original flank wall needs steel designed with the roof and drainage, not after planning. Party Wall etc. Act notices are dual-flank on mid-terrace plots.
4. Drainage and build-over
Side passages often carry shared drains. Building over or near public sewers can need a water-company build-over agreement alongside building control — common on Fulham and similar terrace stock. Flag drains before foundations freeze.
5. Planning drawings then technical drawings
Planning drawings prove envelope and amenity. Building regulations drawings resolve steel, insulation, waterproofing, glazing performance and drainage falls for pricing and construction. See after planning permission.
What is more/less supportable
More defensible: subordinate height, honest sections through neighbours, materials matching host grain, drains coordinated. Less defensible: overbearing flank walls, excessive glazing without thermal strategy, ignoring CA roofscape where visible.
Frequently asked questions
Do side returns need planning permission?
Why do side returns need a structural engineer?
What about party walls?
Why mention drains so often?
Can I open the whole ground floor as one room?
What should I send for a side-return review?
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