Supporting the existing house when creating a basement under an extension is always the biggest challenge. Here sheet piling was used during the excavation and mass filled, hit & miss reinforced concrete sections were excavated and cast in a strict sequence as detailed by the structural engineer
During the renovation of a house in rural Hertfordshire, a new basement was built under the extension. The excavation was stabilised, and house underpinned. From there a new concrete slab and walls were built, creating a new structure.
The new ground floor was cast in place and the whole basement waterproofed using a type C, cavity drainage membrane, linked to a sump and two pumps.