Basement Conversions · SE9 Eltham
Greenwich controls the historic Progress Estate and the Eltham Palace setting; SE9 is a settled, affordable inter-war family market.
Working across the whole borough rather than just this area? See basement conversions in Greenwich.
Basement conversions and lowering existing cellars in Eltham add space without touching the roofline — valuable on SE9's period houses around Eltham, Mottingham, Eltham Park, New Eltham 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 Eltham — structural underpinning design, waterproofing strategy, Party Wall coordination, planning where required, and building regulations through to completion certificate.
Across Eltham, Mottingham, Eltham Park, New Eltham fringe in SE9, the dominant property is inter-war semis and detached houses across eltham and mottingham, with the historic core around eltham palace and pockets of post-war estate. 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 Eltham property, confirm the planning route — Permitted Development, a Lawful Development Certificate, or full planning — and draw a council-ready set tailored to the SE9 streetscape.
Housing stock in SE9: Inter-war semis and detached houses across Eltham and Mottingham, with the historic core around Eltham Palace and pockets of post-war estate.
Within the district: Eltham, Mottingham, Eltham Park, New Eltham fringe.
Streets we know in SE9: the Eltham Park and Progress Estate roads, Court Road, Glenesk Road and the Well Hall streets. Each road has its own building line, boundary treatment and precedent that Greenwich Council weighs when assessing a basement conversion drawings scheme.
Conservation areas: Progress Estate (Well Hall), Eltham Palace, Eltham High Street. Inside these, most external work needs full planning and a Heritage Statement.
Getting around SE9: Eltham, Mottingham and New Eltham rail to London Bridge, Cannon Street and Victoria.
Property values: the 2025 median across SE9 was £473,240 on 646 recorded sales, a 2.9% annual rise. Greenwich house medians that year were £495,000 terraced, £597,500 semi-detached and £742,000 detached.
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 Eltham 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 Eltham'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 Eltham 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.
Yes. The inter-war semis and detached houses around Court Road and Glenesk Road suit rear, side and loft extensions, much of it within Permitted Development outside the conservation areas, confirmed with a Lawful Development Certificate. We confirm the route and draw to Greenwich's checklist.
The Progress Estate is a celebrated First World War garden-suburb conservation area with strong, uniform arts-and-crafts character, so external changes there are tightly assessed on materials, render and roofs. We design sympathetically and submit a full application with a Heritage Statement where the designation applies.
Usually yes on the inter-war semis — a hip-to-gable plus rear dormer within the volume allowance, confirmed by a Lawful Development Certificate, provided you're not in the Progress Estate or another conservation area. We check the constraints for your road and draw it for Building Control.
Eltham's SE9 postcode saw 646 sales in 2025 at a median of £473,240, 2.9% up on the year — Land Registry price-paid figures for the district itself, not an estimate.
Greenwich Council charges its own statutory application fee (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 SE9 address.
For a SE9 project across Eltham, Mottingham, Eltham Park, New Eltham 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 Eltham application through every officer query to the decision.
Eltham (SE9) sits primarily in Greenwich, so applications are decided by Greenwich Council. Conservation areas within SE9 include Progress Estate (Well Hall), Eltham Palace, Eltham High Street, 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 Eltham — 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 SE9'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 SE9 homes.
Householders often approach us after a neighbour used a different council. Our full range is set out for SE3 and SE10.
Pick a slot that suits you. No obligation and no sales pressure, just straight answers on your planning route.
Every SE9 postcode district we draw in, the stock that dominates it and the authority that validates a basement conversion there. SE9 fees below are the statutory England rates for 2026, not basement conversion estimates.
| Postcode | Area | Dominant stock | What it means for a basement conversion |
|---|---|---|---|
| SE9 | Eltham / Mottingham | 1930s semi-detached, post-war flats | Eltham / Mottingham is split at SE9. Either Greenwich Council or Bromley Council can determine a basement conversion here, so the SE9 address is checked against both policies maps first. |
| SE9 | Eltham | 1930s semi-detached, post-war flats | Eltham sits inside SE9; basement conversion proposals here are determined by Greenwich Council. |
| SE9 | New Eltham | 1930s semi-detached | New Eltham sits inside SE9; basement conversion proposals here are determined by Greenwich Council. |
| SE2 | Abbey Wood | mixed stock | Adjoining district to SE9, also inside Greenwich for basement conversion purposes. |
| SE3 | Blackheath / Kidbrooke | Georgian villas, Victorian terraces | Adjoining district to SE9, also inside Greenwich for basement conversion purposes. |
| SE7 | Charlton | Victorian villas, 1930s semi-detached | Adjoining district to SE9, also inside Greenwich for basement conversion purposes. |
| SE20 | Anerley / Penge | Victorian and Edwardian terraces | Adjoining district to SE9, also inside Bromley for basement conversion purposes. |
| BR1 | Bromley / Bickley | Victorian terraces, Edwardian villas, post-war flats | Adjoining district to SE9, also inside Bromley for basement conversion purposes. |
| BR2 | Hayes / Keston | Victorian terraces, Edwardian villas, post-war flats | Adjoining district to SE9, also inside Bromley for basement conversion purposes. |
| BR3 | Beckenham | Edwardian villas, 1930s semi-detached | Adjoining district to SE9, also inside Bromley for basement conversion purposes. |
Roof pitch, wall build-up and plot depth change every few SE9 streets, and each one changes what a basement conversion can achieve at that address.
How designation changes a SE9 (Eltham / Mottingham) basement conversion: Greenwich Council maintains 20 conservation areas, including Eltham Park, Greenwich Town Centre (World Heritage Site), Blackheath. Inside any of them a SE9 (Eltham / Mottingham) basement conversion cannot rely on permitted development, and the route becomes a £548 householder application determined in 8 weeks rather than a £249 prior approval in 6 weeks. Eltham Park sets the tone for SE9 (Eltham / Mottingham) casework.
SE9 (Eltham / Mottingham) permitted development status: there is no borough-wide direction from Greenwich Council, so a basement conversion at a SE9 address is normally still permitted development. We certify that with a £274 Lawful Development Certificate rather than leaving a SE9 (Eltham / Mottingham) sale to argue it later.
The building fabric around SE9 (Eltham / Mottingham): 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. A basement conversion in SE9 (Eltham / Mottingham) is scoped against that stock first, because it decides whether the scheme runs as permitted development, a £274 Lawful Development Certificate, or a full £548 application to Greenwich Council.
How designation changes a SE9 (Eltham / Mottingham) basement conversion: Bromley Council maintains 48 conservation areas, including Beckenham, Keston, Bickley. Inside any of them a SE9 (Eltham / Mottingham) basement conversion cannot rely on permitted development, and the route becomes a £548 householder application determined in 8 weeks rather than a £249 prior approval in 6 weeks. Bickley sets the tone for SE9 (Eltham / Mottingham) casework.
SE9 (Eltham / Mottingham) permitted development status: there is no borough-wide direction from Bromley Council, so a basement conversion at a SE9 address is normally still permitted development. We certify that with a £274 Lawful Development Certificate rather than leaving a SE9 (Eltham / Mottingham) sale to argue it later.
The building fabric around SE9 (Eltham / Mottingham): Large 1930s detached and semi-detached in Chislehurst and Bickley; Edwardian in Beckenham; Victorian in Bromley town; Metropolitan Green Belt covers significant rural-fringe land. Largest London borough by area; substantial Green Belt; conservation areas in most town centres; generally permissive elsewhere. A basement conversion in SE9 (Eltham / Mottingham) is scoped against that stock first, because it decides whether the scheme runs as permitted development, a £274 Lawful Development Certificate, or a full £548 application to Bromley Council.
Sources for this SE9 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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