Tunnelled Basement
Tunnelled Basement
A logistically complex basement extension—comprising a swimming pool and wellness spaces—constructed beneath a recently refurbished family home while the property remained fully occupied throughout.
Following the completion of a two-year refurbishment of their home, the clients approached us with a desire to add a leisure space below ground—something their original scheme had not accommodated. Their previous architect had advised that a basement would be unfeasible.
However, we were undertaking the full refurbishment and new-build basement at the neighbouring property (HOLLAND PARK I), prompting an investigation into whether tunnelling from one property to the other would be possible.
A strategy was devised to excavate and build the new basement entirely from the neighbouring site, where groundworks were already in progress. By working collaboratively with both clients, we were able to construct the full basement extension while the family remained in occupation and without entering or altering the completed house above – a unique opportunity.
The existing concrete slab was of sufficient depth to nearly self-support the full weight of the property. This was structurally enhanced by a system of steel beams, brought in as segmented sections and welded in situ due to the confined site conditions. Together, these measures allowed the home to remain untouched and fully operational during the excavation process.
The resulting space includes a height-adjustable swimming pool that can transition from full-depth swimming to a flush floor – allowing for a range of uses from table tennis to entertaining. Adjacent to this are a cold plunge pool, sauna, bar, and changing area with shower. A hydroponically sustained green wall adds a calmness, texture and acoustic absorption, while a precisely modelled ceiling conceals services and optimises sound performance.
A strategy was devised to excavate and build the new basement entirely from the neighbouring site.
The space includes a height-adjustable swimming pool that can transition from full-depth swimming to a flush floor.
A hydroponically sustained green wall adds a calmness, texture and acoustic absorption, while a precisely modelled undulating ceiling conceals services and further optimises sound performance.
