Rear extension in RM13
RM13 covers Rainham & South Hornchurch. For a rear extension, the route depends on the exact property: conservation areas, Article 4 directions, listed status, tenure and the scheme details all change the answer. Use this district guide as local context, then run the address check before relying on permitted development or any consent assumption.
RM13 covers Rainham and South Hornchurch — the Rainham conservation area around Rainham Hall, near the Thames-side marshes. Much of the stock keeps permitted development rights for rear and loft projects, with the borough's HMO Article 4 the control most likely to apply.
First checks for rear extension
Service-specific- Whether it's permitted development or needs a planning application
- Party wall agreements with both neighbours
- A public sewer crossing the footprint (build-over agreement)
District pages are not point-level checks. They do not confirm whether a specific property is listed, inside a conservation area, or subject to an Article 4 direction.
Local planning context · Havering
Real · planning.data.gov.ukHavering has 11 conservation areas and 0 Article 4 areas in the official dataset. RM13 is too broad to say which apply to your property; the address check tests the point against available geometry.
Read the borough-wide context on the Havering planning guide.
What changes the route?
| Where constraints apply | Likely a full householder planning application — conservation-area status removes side and two-storey rear extensions, and flats have no PD rights; a single-storey rear on a house may still be permitted development. |
| Where no designation is found | May be permitted development — confirm with a lawful development certificate before you design. |
Approvals and who deals with them
| What you may need | Likelihood | Who usually deals with it |
|---|---|---|
| Planning permission / permitted development PD may cover a modest single-storey rear extension on a whole house; flats have no PD rights, and conservation-area status removes side and two-storey rear extensions — any of which pushes a scheme to a full application. Confirm permitted development with a lawful development certificate rather than assuming it. | Possible | Planning consultant / architect |
| Building Regulations approval Required for the structure, foundations, drainage, insulation and glazing. | Required | Building control + your builder |
| Party Wall etc. Act 1996 notice Excavating within 3m of a neighbour's structure or building on the boundary line triggers the Act — serve notices early. | Likely | Party wall surveyor |
| Structural engineer's design Foundations and any structural opening into the existing rear wall need an engineer. | Required | Structural engineer |
| Drainage build-over agreement If the extension crosses a public sewer, a build-over agreement with the water authority is needed. | Possible | Drainage engineer + water authority |
| Listed building consent We do NOT check listed status. If the property is listed, consent is needed for works affecting its character — confirm on the National Heritage List for England. | Verify | Heritage adviser / conservation officer |
Cost context
| Cost per m² — lower (straightforward) | £3,000 / m² |
| Cost per m² — typical | £3,800 / m² |
| Cost per m² — higher (complex / conservation spec) | £4,600 / m² |
| Typical project (12–18 m²) | £36,000 – £83,000 |
Indicative London ranges calibrated from real project data. VAT and professional/party-wall fees are additional.
Watch-outs in RM13
- Article 4 directions bite on front-and-side appearance (solar panels, windows, boundary works), not on a single-storey rear — but they're drawn property by property, so verify at the address rather than assuming from the borough.
- The 45-degree daylight test trimming depth on tight terraced gardens.
- Party wall awards on both flanks adding cost and programme before a brick is laid.
- Conservation-area material conditions (brick match, lime mortar) discovered after pricing, not before.
Next steps
- Confirm the planning route — lawful development certificate (PD) or a householder application — before committing to a design.
- Brief an architect/designer and a structural engineer from these facts.
- Serve Party Wall notices to both neighbours well before the start date.
- Check for a public sewer crossing the footprint and budget for a build-over agreement if so.
Related guides
The size limits, the exceptions, and the postcode-level traps.
Read the guide →Real ranges from real projects — not brochure numbers.
Read the guide →Bigger single-storey rear extensions without a full planning application — but it's a notification process, not a free pass.
Read the guide →Almost every London extension, loft and basement engages this Act. Here's how it actually works.
Read the guide →More services in RM13
First check: Freeholder consent / Licence to Alter — read your lease's alterations clause
Service guide →First check: A structural engineer's check on whether the wall is load-bearing
Service guide →First check: Whether the dormer needs planning permission
Service guide →First check: Planning permission and the borough's basement policy
Service guide →First check: The intended use (office/gym vs sleeping) — it changes everything
Service guide →First check: The property's planning history and any enforcement
Service guide →First check: Whether the building is listed, and at what grade
Service guide →Planning Permission Checker provides planning and cost intelligence for early feasibility only. It is not legal, planning, valuation, architectural, structural, or surveying advice. All estimates are indicative and must be verified by qualified professionals before purchase, design, planning submission, or construction.
Cost estimates are indicative only — not a quotation. Final price depends on survey, specification, structure, access, party wall matters, VAT, professional fees, and contractor availability.
Planning outcomes are not guaranteed. Local planning authorities make final decisions.