More space, without moving house — build down.

Converting an existing cellar into habitable space can often be done under permitted development, while excavating a new basement or enlarging one usually needs a full planning application. Every London borough treats basements slightly differently — we'll tell you honestly at the first site visit what your project is likely to need, and we work alongside your architect or planning consultant throughout.

Yes — when it's done in the right sequence. Every dig follows the structural engineer's design: underpinning is dug and poured one numbered pin at a time in a strict hit-and-miss sequence, with temporary propping, so the building above stays fully supported throughout. Each stage is inspected and recorded for building control, and party wall requirements with your neighbours are part of nearly every London job we do.

It depends on the scope. A straightforward basement conversion of an existing cellar is measured in weeks; a full basement excavation with underpinning under an existing house is a bigger undertaking and typically runs for several months, depending on size, depth and ground conditions. You get a realistic programme with your quote — not an optimistic one — and we keep you updated as each stage is signed off.

Every basement is priced individually — the dig depth, ground conditions, access and level of fit-out all move the figure, so headline day-one rates tend to mislead. What we provide instead is a free site visit and a fully itemised quote built around the structural engineer's design, with no vague provisional sums. Request a quote and we'll give you a realistic figure for your property.

Waterproofing is designed to BS 8102, normally combining a cavity drain membrane with a sump and pump system, and a second form of protection where the design requires it. As a certified Delta Membranes and Wykamol contractor, our waterproofing systems are installed to the manufacturer's specification and carry manufacturer-backed guarantees.

Almost anything an above-ground room is used for: a kitchen and living space, a home cinema or gym, utility and plant rooms, or a guest bedroom with a lightwell. We advise on ceiling heights, natural light and escape routes early in the design, so the finished space is genuinely habitable — browse our completed projects for ideas.

Usually not. On most projects the dig is accessed from outside and the house stays liveable above the works, with the noisiest phases agreed with you in advance. Where a deeper, double-storey dig makes day-to-day living harder, we'll say so honestly at survey stage rather than let you find out mid-project.