Drawings for going down instead of out — a new floor dug beneath your Lambeth house, underpinned and tanked, detailed with the structural method statement and drainage strategy Lambeth Council and building control both need, delivered as a coordinated set and revised free until approved, with a free feasibility check first.
Lambeth Council granted 89% of the householder planning decisions it made in its latest published year — 2 points above the 87% England-wide householder average. The loss of family houses to further flat conversion is resisted and frequently the deciding issue, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901) and Edwardian (1901–1910) housing stock sets the design brief on most streets.
Before permission is required, Class B allows 40m³ of added loft volume on a terrace and 50m³ on a semi or detached house, and Class A allows a 3m single-storey rear extension on a terrace or 4m on a detached house. Lambeth carries at least one Article 4 direction, and conservation areas including Clapham Old Town, Stockwell Park and Angell Town remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Lambeth is determined against an 8-week statutory target.
Clapham (Georgian and Victorian terraces around the Old Town and Common), Brixton (Victorian terraces heavily subdivided into flats), Stockwell (Georgian and Victorian streets around Stockwell Park), Herne Hill (Victorian villas and terraces on the Dulwich fringe), Streatham (Edwardian terraces and mansion blocks along the high road) and Kennington (Georgian and Regency terraces near the river) — these are the Lambeth pockets our drawings cover most. Heritage designations here include Clapham Old Town, Stockwell Park, Angell Town, Herne Hill and Leigham Court Estate. Lambeth Council weighs each proposal against Lambeth Local Plan and the council's Alterations and Extensions SPD, where mansards and roof additions on stucco-fronted terraces are measured against whatever original roofline survives on the street. Much of Brixton, Clapham and Stockwell is already converted flats and maisonettes, which hold no householder permitted-development rights.. On roofs the borough is butterfly and valley roofs behind the terrace parapets and mansard and pitched roofs on the taller stucco streets, over Georgian and Victorian terraces, converted flats and maisonettes and purpose-built mansion blocks and estates.
When a Lambeth house cannot grow outward — no garden to lose, a footprint already at its limit — the only direction left is down. The tall Georgian and Victorian terraces, converted flats and maisonettes and purpose-built mansion blocks and estates that fill the borough sit on foundations shallow enough to underpin, and a dug-down lower ground floor buys a whole storey of living space beneath the existing house without changing the street at all. The value is real; so is the engineering, and Lambeth Council treats a basement as a major structural intervention rather than a simple conversion.
The drawings carry more weight than any other project because the ground itself is the risk. The existing walls are underpinned in sequence so the house is never left unsupported; a new retaining structure holds back the surrounding soil; the slab and walls are tanked — usually a Type C cavity-drain system with a sump and pump — because a basement is below the water table for part of the year. The loss of family houses to further flat conversion is resisted and frequently the deciding issue, exactly the kind of constraint a basement scheme has to answer before Lambeth Council will validate it.
Many of Lambeth's basements sit under listed or conservation-area houses — Clapham Old Town, Stockwell Park, Angell Town, Herne Hill and Leigham Court Estate among them — where a front lightwell, a rooflight in the pavement vault or any change to the historic fabric is scrutinised closely. Alongside the controls in conservation areas such as Clapham Old Town, Lambeth runs a borough-wide Article 4 direction removing permitted-development rights for small shared houses, pulling many HMO changes into the application system. We establish the designation and the borough's basement policy before a single line is drawn.
Most basements in Lambeth need a full planning application to Lambeth Council, and almost always the supporting technical documents too. Expect to apply where any of these apply — which is nearly every dig-down:
We produce the planning drawings, the structural scheme with its method statement, the waterproofing and drainage strategy and the party-wall information as a single coordinated package for Lambeth Council and building control, so the engineer, the council and the neighbour are all reading the same set — the way a basement stays on programme.
Below is Lambeth Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Lambeth grants a high proportion of householder applications, but with so much of its stock already split into flats, protecting the remaining family houses is what shapes most refusals. Basements are decided on the strength of their technical case — a complete Basement Impact Assessment and method statement move a scheme through validation and committee far faster than a bare application.
Source: MHCLG planning application statistics (householder decisions, rolling year). Compare every borough on our London approval-rate league table.
Tell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
A basement is won twice — once at planning and once at building control — and both hang on the technical set. Lambeth Council's planners weigh the impact on neighbours, on groundwater and on the character of the street, so the application leads with a Basement Impact Assessment and, where the policy asks, a construction management plan. Building control and the warranty provider then check the underpinning sequence, the retaining design, the waterproofing to the current standard and the means of escape from a habitable room below ground. Across Clapham, Brixton and Stockwell these are the details that decide whether a basement is a clean approval or a year of conditions.
Mansards and roof additions on stucco-fronted terraces are measured against whatever original roofline survives on the street. Because you are excavating within a few metres of a neighbour's wall, the Party Wall etc. Act almost always applies, and we set the drawings up so the party-wall surveyor, the structural engineer and the waterproofing designer are all working to one agreed section — the coordination that keeps a Lambeth basement out of dispute and on programme.
We draw dig-downs and cellar conversions under the tall period houses across the borough. A few of the Lambeth neighbourhoods where basements come up most often:
Basement conversion drawings for Clapham's Georgian and Victorian terraces around the Old Town and Common — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
Basement conversion drawings for Brixton's Victorian terraces heavily subdivided into flats — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
Basement conversion drawings for Stockwell's Georgian and Victorian streets around Stockwell Park — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
Basement conversion drawings for Herne Hill's Victorian villas and terraces on the Dulwich fringe — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
Basement conversion drawings for Streatham's Edwardian terraces and mansion blocks along the high road — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
Basement conversion drawings for Kennington's Georgian and Regency terraces near the river — underpinning-sequenced, tanked and drawn with the structural and drainage set Lambeth Council needs.
A basement is the most document-heavy project a house can have. This is what each part of the set does and who checks it.
| Element | What it covers | Why it matters | Checked by |
|---|---|---|---|
| Underpinning | Deepening the existing foundations in a sequence | Keeps the house supported while you dig beneath it | Structural engineer / building control |
| Retaining & waterproofing | New retaining walls and Type C cavity drainage | Holds back the soil and keeps the room dry below the water table | Building control / warranty |
| Basement Impact Assessment | Groundwater, structure and neighbour impact | Required by Lambeth Council's basement policy for planning | Planning |
| Party wall | Notices and award where you dig near a boundary | The legal route to excavate beside a neighbour's wall | Party-wall surveyors |
Under a listed or conservation-area house — such as in Clapham Old Town and Stockwell Park — a front lightwell or vault alteration adds a further layer of consent to the basement application.
A staged process built around the technical case a basement lives or dies on — feasibility first, so you never commit to a dig that the ground or the policy will not allow.
Send us your Lambeth postcode and what you want below ground. We check Lambeth Council's basement policy, conservation and listed status, and the likely ground and groundwater constraints before you spend on design.
We survey the house, establish existing foundation depths and levels, and coordinate the structural engineer so the underpinning and retaining scheme is built on real dimensions, not assumptions.
We produce the planning drawings with the Basement Impact Assessment and construction management plan, plus the structural method statement and waterproofing strategy, as one coordinated package for Lambeth Council.
We submit to Lambeth Council, answer planning and building-control queries, dovetail the party-wall process, and revise the set free until the basement is approved and signed off.
Nearly always. Excavating to create new space, deepening a cellar or forming a lightwell goes beyond permitted development, and most inner-London boroughs — Lambeth Council included — run a specific basement or subterranean-development policy. A full planning application is the norm, usually supported by a Basement Impact Assessment. We confirm the exact policy route for your Lambeth address before any drawing starts.
A Basement Impact Assessment is a technical report on how the dig affects groundwater, drainage, structure and neighbouring buildings, and most Lambeth basement schemes need one to satisfy Lambeth Council's policy. It is the document planners lean on most, because it shows the excavation has been thought through rather than assumed. We coordinate it with the structural design so the two tell the same story.
Almost certainly. A basement means excavating close to — and often underpinning beneath — a neighbour's wall, which triggers the Party Wall etc. Act 1996. You must serve notice on the adjoining owners and usually reach a party-wall award before you dig. We set the drawings up so the party-wall surveyor works from the same sections as the engineer, which keeps a Lambeth basement out of dispute. Lambeth Council is the decision-maker.
A basement sits below ground and, for part of the year, below the water table, so it is designed to be watertight rather than merely damp-proofed. The usual approach is a Type C cavity-drain system that collects any water behind the walls and floor and takes it to a sump and pump. We draw the waterproofing to the current British Standard and coordinate it with the structure, because in a Lambeth basement the tanking and the retaining wall have to work as one. Lambeth Council is the decision-maker.
Sometimes, but it is harder. A listed house — or one in a conservation area such as Clapham Old Town and Stockwell Park — needs listed building consent for any work affecting its fabric, and Lambeth Council scrutinises lightwells, vault alterations and the effect on the historic structure closely. It can be done where the scheme protects what matters, but the justification has to be thorough. We assess the designation honestly before recommending a dig.
We price each Lambeth basement individually, because the depth, the ground conditions, the party-wall count and the planning policy all vary house to house, and send a fixed, no-obligation quote within one working day. It covers the coordinated planning and technical set with free revisions until Lambeth Council approves. The structural engineer, Basement Impact Assessment specialist and any council fee are separate. Call 020 7864 7245 to start.
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