Basement Conversions · SE3 Blackheath
Greenwich controls the Blackheath and Cator Estate conservation areas; the post-war Span estates also carry conservation protection.
The borough-level guide to basement conversions in Greenwich sets out how the same work is handled across the rest of the authority.
Basement conversions and lowering existing cellars in Blackheath add space without touching the roofline — valuable on SE3's period houses around Blackheath, Blackheath Village, Kidbrooke, Westcombe Park fringe. Greenwich Council reviews structural, drainage and flood-risk impact, and a Party Wall award plus a Thames Water build-over agreement are usually required. We coordinate the structural engineer and the waterproofing design.
Full architectural technology service for basement digs and cellar conversions in Blackheath — structural underpinning design, waterproofing strategy, Party Wall coordination, planning where required, and building regulations through to completion certificate.
Across Blackheath, Blackheath Village, Kidbrooke, Westcombe Park fringe in SE3, the dominant property is georgian and victorian houses around blackheath, large detached and semi-detached villas, and the modernist span estates of kidbrooke. That stock shapes what basement conversion drawings looks like here: the right approach for a period terrace differs from a mansion-block flat or a new-build, and Greenwich Council judges each on design quality and neighbour impact. We survey the specific Blackheath property, confirm the planning route — Permitted Development, a Lawful Development Certificate, or full planning — and draw a council-ready set tailored to the SE3 streetscape.
Housing stock in SE3: Georgian and Victorian houses around Blackheath, large detached and semi-detached villas, and the modernist Span estates of Kidbrooke.
Within the district: Blackheath, Blackheath Village, Kidbrooke, Westcombe Park fringe.
Streets we know in SE3: the Cator Estate roads, Blackheath Park, Montpelier Row and the Span estates off Foxes Dale. Each road has its own building line, boundary treatment and precedent that Greenwich Council weighs when assessing a basement conversion drawings scheme.
Conservation areas: Blackheath Park (Cator Estate), Blackheath Village, Westcombe Park. Inside these, most external work needs full planning and a Heritage Statement.
Getting around SE3: Blackheath and Kidbrooke rail to London Bridge, Cannon Street and Victoria.
Regeneration: Blackheath falls within or beside the Kidbrooke Village (one of London's largest estate regenerations), which shapes local planning policy and design expectations.
Property values: around £450,000 for a flat and £900,000-£1.6m for a house — a useful gauge of the build value an extension or loft adds in SE3.
Borough character: World Heritage Site status in Greenwich town centre adds heritage weight; outer borough areas (Eltham, Thamesmead) generally permissive.
Desktop study plus measured survey assessing existing foundations, ground conditions, water table level and underpinning viability for your Blackheath property.
New-build basements and lightwell extensions need planning permission. Cellar conversions of existing space are usually Permitted Development. We confirm the route and submit where needed.
Underpinning sequence drawings, reinforced concrete design, temporary works strategy — all to Eurocode with chartered engineer sign-off.
BS 8102:2022 compliant — cavity drain, cementitious tanking or membrane system specified for Blackheath's ground conditions and water table.
Full Plans application to Greenwich Council Building Control or an approved inspector covering structure (Part A), fire safety (Part B), damp-proofing (Part C), ventilation (Part F) and thermal performance (Part L).
Almost every Blackheath basement triggers Party Wall notices. We also manage Thames Water Build Over Agreements where within 3m of a public sewer.
Single planning or building-regs submission.
Planning + building regs + structural.
Listed, conservation or complex sites.
Strongly. The Blackheath, Blackheath Park (Cator Estate) and Westcombe Park conservation areas mean full planning with a Heritage Statement for external changes, and Greenwich scrutinises materials, boundaries and roofscape closely. We design to that standard for the Georgian and Victorian houses around the heath.
It needs care. The modernist Span estates off Foxes Dale are conservation areas with strong design controls and residents' covenants protecting their original character, so even windows and finishes are controlled. We design sympathetically to the Span aesthetic and handle both the planning and any management-company consent.
Kidbrooke Village is one of London's largest estate regenerations — thousands of new homes, a new station forecourt and parkland — lifting values across SE3. For an individual house project the binding controls remain Permitted Development limits and the local conservation designation, which we check for your address.
Outside the conservation areas, usually yes — a rear dormer or hip-to-gable within the volume allowance, confirmed by a Lawful Development Certificate. Inside the Blackheath or Cator Estate designations, roof changes need full planning and are assessed on their impact on the historic roofscape. We confirm which applies to your road.
With Blackheath property at around £450,000 for a flat and £900,000-£1.6m for a house, the professional drawing fee is a small fraction of the value the work adds to SE3's georgian and victorian houses around blackheath, large. Greenwich Council charges its own statutory application fee on top (currently £548 for a householder planning application, £610 for a full application). We quote the drawings as one fixed price and the free site survey covers every SE3 address.
For a SE3 project across Blackheath, Blackheath Village, Kidbrooke, Westcombe Park fringe, expect roughly 3–4 weeks from instruction to submission: week 1 the measured survey, weeks 2–3 the drawings and your revisions, then validation and the statutory determination by Greenwich Council (8 weeks for a householder application). We carry the Blackheath application through every officer query to the decision.
Blackheath (SE3) sits primarily in Greenwich, so applications are decided by Greenwich Council. Conservation areas within SE3 include Blackheath Park (Cator Estate), Blackheath Village, Westcombe Park, where full planning and a Heritage Statement are required. We confirm the planning route for your exact address before quoting.
Almost always. Any structural work behind basement conversion drawings in Blackheath — new openings, steel beams, loft floors, foundations — needs Building Regulations approval covering structure (Part A), fire escape (Part B) and insulation (Part L), submitted to Greenwich Council Building Control or an approved inspector. On SE3's typically terraced and semi-detached stock, a Party Wall notice to adjoining neighbours is normally required before the steelwork. We coordinate both as part of the Complete package.
In value terms, yes. The bigger risk is an unapproved or non-compliant scheme — which is why council-ready drawings and a clean Building Control sign-off matter on SE3 homes.
Extensions on a boundary plot can involve two authorities. Everything we draw and submit is listed for SE9 and SE10.
Pick a slot that suits you. No obligation and no sales pressure, just straight answers on your planning route.
Every SE3 postcode district we draw in, the stock that dominates it and the authority that validates a basement conversion there. SE3 fees below are the statutory England rates for 2026, not basement conversion estimates.
| Postcode | Area | Dominant stock | What it means for a basement conversion |
|---|---|---|---|
| SE3 | Blackheath / Kidbrooke | Georgian villas, Victorian terraces | A basement conversion in Blackheath / Kidbrooke may land with Greenwich Council or Lewisham Council — SE3 crosses the boundary, and the SE3 policies map decides it street by street. |
| SE3 | Blackheath (Greenwich) | Georgian villas, Victorian terraces | Blackheath (Greenwich) sits inside SE3; basement conversion proposals here are determined by Greenwich Council. |
| SE3 | Kidbrooke | New-build, post-war fragments | Kidbrooke sits inside SE3; basement conversion proposals here are determined by Greenwich Council. |
| SE3 | Blackheath | Georgian villas, Victorian terraces | Blackheath sits inside SE3; basement conversion proposals here are determined by Lewisham Council. |
| SE2 | Abbey Wood | mixed stock | Adjoining district to SE3, also inside Greenwich for basement conversion purposes. |
| SE7 | Charlton | Victorian villas, 1930s semi-detached | Adjoining district to SE3, also inside Greenwich for basement conversion purposes. |
| SE9 | Eltham / Mottingham | 1930s semi-detached, post-war flats | Adjoining district to SE3, also inside Greenwich for basement conversion purposes. |
| SE4 | Brockley | Victorian and Edwardian terraces | Adjoining district to SE3, also inside Lewisham for basement conversion purposes. |
| SE6 | Catford / Bellingham | 1930s semi-detached, post-war flats | Adjoining district to SE3, also inside Lewisham for basement conversion purposes. |
| SE8 | Deptford | Georgian terraces, post-war estates, new-build | Adjoining district to SE3, also inside Lewisham for basement conversion purposes. |
| SE12 | Lee / Grove Park | mixed stock | Adjoining district to SE3, also inside Lewisham for basement conversion purposes. |
Roof pitch, wall build-up and plot depth change every few SE3 streets, and each one changes what a basement conversion can achieve at that address.
Conservation areas covering SE3 (Blackheath / Kidbrooke): Greenwich Council runs 20, and Charlton, Eltham Park, Greenwich Town Centre (World Heritage Site) are the ones SE3 (Blackheath / Kidbrooke) owners meet most. A basement conversion inside a SE3 (Blackheath / Kidbrooke) conservation area loses permitted development, so the SE3 (Blackheath / Kidbrooke) submission is a householder application at £548 decided in 8 weeks — not a £249 prior approval decided in 6 weeks. In Greenwich Town Centre (World Heritage Site) a basement conversion is judged on the street elevation first.
Article 4 and your SE3 (Blackheath / Kidbrooke) basement conversion: Greenwich Council has made no borough-wide direction, so permitted development for a basement conversion in SE3 (Blackheath / Kidbrooke) generally survives outside SE3 (Blackheath / Kidbrooke) conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a SE3 owner records that a basement conversion was lawful.
What SE3 (Blackheath / Kidbrooke) is built from: Georgian in Greenwich town centre; Victorian terraces in East Greenwich, Charlton; inter-war semi-detached in Eltham; new-build along the riverside. World Heritage Site status in Greenwich town centre adds heritage weight; outer borough areas (Eltham, Thamesmead) generally permissive. That mix decides the basement conversion route in SE3 (Blackheath / Kidbrooke) more than the postcode does, and it is what a Greenwich Council case officer reads first. A householder application costs £548 paid to Greenwich Council direct, with 8 weeks to a decision once validated.
Conservation areas covering SE3 (Blackheath / Kidbrooke): Lewisham Council runs 30, and Blackheath, Deptford High Street, Forest Hill are the ones SE3 (Blackheath / Kidbrooke) owners meet most. A basement conversion inside a SE3 (Blackheath / Kidbrooke) conservation area loses permitted development, so the SE3 (Blackheath / Kidbrooke) submission is a householder application at £548 decided in 8 weeks — not a £249 prior approval decided in 6 weeks. In Blackheath a basement conversion is judged on the street elevation first.
Article 4 and your SE3 (Blackheath / Kidbrooke) basement conversion: Lewisham Council has made no borough-wide direction, so permitted development for a basement conversion in SE3 (Blackheath / Kidbrooke) generally survives outside SE3 (Blackheath / Kidbrooke) conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a SE3 owner records that a basement conversion was lawful.
What SE3 (Blackheath / Kidbrooke) is built from: Victorian and Edwardian terraces across Brockley, Honor Oak, Forest Hill; 1930s semi-detached in Catford and Hither Green; post-war mixed in Deptford. Generally permissive planning compared to central boroughs; loft conversions and side-return extensions routinely approved under PD. That mix decides the basement conversion route in SE3 (Blackheath / Kidbrooke) more than the postcode does, and it is what a Lewisham Council case officer reads first. A householder application costs £548 paid to Lewisham Council direct, with 8 weeks to a decision once validated.
Sources for this SE3 basement conversion page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.
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