Improving at BR3 3SJ

What you could build at BR3 3SJ: the planning rules at this address, what neighbours have built and how big, planning decisions nearby, rough costs and the value an extension adds, and how to get started. In Beckenham East & Kelsey Park, Bromley.

45extensions seen within 600 m in the last 10 years

2loft conversions within 600 m in the last 10 years

78%of 67 householder applications nearby approved (since 2023)

64.1extensions per 1,000 homes in the neighbourhood (10 years)

● work seen on energy certificates · ● application approved · ● refused · ● pending or other · ● this postcode

The rules at this address

Houses usually have permitted development rights: some rear extensions (typically up to 3 m deep for a semi or terrace, 4 m detached), loft conversions within volume limits, and porches can go ahead without planning permission. Larger single-storey rear extensions (up to 6 m / 8 m) can use the “prior approval” neighbour scheme.
Not in a conservation area (from council registers).
No Article 4 direction recorded for this postcode.
Listed buildings need listed building consent for most changes, inside and out: check the National Heritage List.
To be certain work is permitted development, apply for a lawful development certificate (about £129 for householders in England). Building regulations apply either way.

What neighbours have built

Home	Work	Seen	Space added	Floor area	Rooms	Distance
3, Beck Way	Extension	2026	+22 m²	73 m² → 95 m²	5 → 5	361 m
47, Village Way	Extension	2026	+18 m²	116 m² → 134 m²	–	557 m
183, Eden Park Avenue	Extension	2026	+47 m²	86 m² → 133 m²	5 → 6	589 m
49, Birchwood Avenue	Extension	2026	+26 m²	83 m² → 109 m²	–	596 m
5, Birchwood Avenue	Extension	2026	+31 m²	107 m² → 138 m²	–	596 m
37, Beck Way	Extension	2025	+21 m²	98 m² → 119 m²	5 → 5	361 m

Planning applications nearby

Address	Work	Outcome	Decided	Drawings and agent
21, Forest Ridge, Br3 3nh	Loft or dormer	Under consideration	–	25/01872/FULL6
33, Glanfield Road, Br3 3js	Rear extension	Under consideration	–	25/01983/FULL6
38, Wellhouse Road, Br3 3jr	Rear extension	Approved	Jun 2025	25/01074/FULL6
72, Village Way, Br3 3nr	Loft or dormer	Refused	May 2025	25/00863/FULL6
48, Glanfield Road, Br3 3ju	Rear extension	Not needed / lawful	Apr 2025	25/01095/HHPA
48, Greenways, Br3 3nq	Loft or dormer	Approved	May 2025	25/00762/FULL6

How often householder applications are approved

Work	Beckenham East & Kelsey Park	Bromley	London	Typical decision time
All householder applications	82% (72)	79% (3770)	80%	8 weeks
Loft or dormer	83% (23)	73% (1144)	81%	8 weeks
Rear extension	88% (8)	89% (1056)	79%	8 weeks
Two-storey extension	73% (11)	70% (543)	72%	8 weeks
Other householder work	67% (9)	54% (294)	70%	8 weeks
Side return or wrap-around	–	94% (154)	88%	8 weeks
Windows, doors or cladding	83% (6)	85% (85)	90%	8 weeks
Outbuilding or garden room	–	83% (107)	79%	8 weeks
Side extension	–	93% (144)	86%	8 weeks
Garage conversion or garage

Cost and the value it adds

Across England and Wales, homes extended by a typical 30 m² and then resold rose about 11.1% more than similar homes nearby over the same years (124,884 resales). How extensions pay off by size, type and region.

Single-storey rear or side extension: about £2,000–£3,000 per m² (London £2,500–£4,000), plus fees and VAT
Loft conversion: about £45,000–£75,000 for a dormer; more for a mansard or hip-to-gable
Two-storey extension: about £1,800–£2,800 per m² of new floor
Garage conversion: about £15,000–£30,000
Basement: about £3,500–£5,000 per m², London mostly

Build costs are rough 2026 ranges from industry guides, not quotes. Get three quotes for your plans.

Move or improve?

The money you don't get back either way, for the same extra space in Beckenham East & Kelsey Park.

Your home is worthExtra space you need (m²)Homes here sell for, per m²Building cost per m²Share of that an extension adds (%)

Move to a home 20 m² bigger (about £587,000)

Stamp duty on the new home	£19,350
Estate agent on yours 1.2% + VAT	£6,768
Solicitors, buying and selling	£3,000
Survey	£600
Removals	£1,500
Money gone	£31,218

Extend by 20 m²

Building, plus 15% for design, planning and contingency	£57,500
Less what it adds to your home's value 60% of the local price	−£70,200
Money gone	−£12,700

On these figures, extending loses about £43,918 less. Moving also changes the area, the schools and the commute; extending means months of building work and depends on planning.

Building costs vary a lot (a single-storey rear extension is often £2,000–£3,000 per m², more in London). How much space adds depends on the home and street: what extensions added to resale prices. A guide, not advice; nothing you type leaves this page.

Getting started

Look at what neighbours did. Open applications above to see drawings that were approved on similar houses, and who designed them.
Check the route: permitted development (with a lawful development certificate), prior approval for larger rear extensions, or full householder planning permission.
Get a measured survey and a designer: an architect, an architectural technologist or a designer who handles planning drawings.
Apply (householder permission is about £258 in England; councils aim to decide within 8 weeks).
Building regulations through the council's building control or an approved inspector, and party wall notices to neighbours if you build on or near the boundary.
Choose a builder: written quotes, a contract, staged payments, and check their insurance and references.

Find help: RIBA Find an Architect ↗ · CIAT architectural technologists ↗ · TrustMark tradespeople ↗ · Federation of Master Builders ↗ · Planning Portal guides ↗

General guidance, not planning or legal advice. Fees and rules as checked in October 2026; confirm with the council.

Energy certificates: MHCLG (OGL). Planning applications: GLA Planning London Datahub. Conservation areas and Article 4: planning.data.gov.uk (OGL).

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