Single-storey basement extensions to Holland Park houses — designed within RBKC’s strict basement policy, with the Basement Impact Assessment, underpinning and waterproofing under one team.
Speak to the studio directly: 020 8054 8756
A basement extension adds a full new floor without changing the look of the house from the street — which is why it is one of the few ways to gain serious space in Holland Park’s protected streetscape. Done properly it gives a light, dry, fully tanked room for a kitchen, media room, gym or guest suite.
RBKC has one of the strictest basement policies in London. New basements are generally limited to a single storey, must not extend under more than half of the garden, need at least a metre of soil above any part under the garden, and require a Basement Impact Assessment covering structure and groundwater, plus a Construction Traffic Management Plan.
We design within that policy from the outset — there is no point proposing a basement RBKC will refuse. Engineering, underpinning, waterproofing and the planning case all sit in one design-and-build contract with a single point of responsibility.
In RBKC, the basement policy — not just your ambitions — sets what is buildable.
RBKC policy generally limits a new basement to one storey under the house and part of the garden.
A BIA covering structure, ground movement and groundwater is required before consent — we commission and coordinate it.
No more than half the garden, with a metre of soil above for planting — the design has to respect this.
A Construction Traffic Management Plan and method statements govern how the work is carried out on a tight site.
From feasibility against RBKC policy to a dry, finished basement — all in-house.
Testing the site against RBKC basement policy before any design work begins.
Commissioning the Basement Impact Assessment, structural method and CTMP.
Drawings and a planning case for a compliant single-storey basement.
Sequential, engineer-designed underpinning to form the new depth safely.
Retaining structure, propping and party wall awards with neighbours.
Type C cavity-drain or tanked systems with pumps and a maintainable design.
Lightwells, sun-pipes and mechanical ventilation to make the room usable.
Kitchen, gym, media or guest-suite fit-out, snagging and handover.
We design and build single-storey basements within RBKC policy across Holland Park’s terraces and villas.
Holland Park sits within the Royal Borough of Kensington & Chelsea — see our Holland Park area page and South West London refurbishment overview.
Book a no-obligation consultation at 2 Eaton Gate in SW1, at our Hampstead studio, or at your property. We will give you an honest read on approvals, programme and budget band — in pounds sterling — before you commit.
Site visit · approvals read · outline budget band (GBP) · programme indication. No obligation.
Send Project DetailsThe same NW3 design-build team covers the neighbouring areas: