Martin Gruenanger and his wife, Rebecca McKelvey, have successfully doubled the size of their Edwardian ground-floor flat in Wanstead, east London, by excavating beneath their property. Faced with limited options for expanding their 85 square meter home—unable to build upwards or outwards and reluctant to relocate—the couple opted to dig four meters deep, increasing the total space to 175 square meters.

The flat, located in the Aldersbrook conservation area, was purchased in 2014 and required extensive renovation due to fire damage, a flooded basement, and a lack of functional bathrooms. Since then, the couple invested approximately £120,000 in the property, transforming it into a family home suited to their needs. Despite the challenges, they were determined to stay in the area, which offers access to open grasslands, parks, Epping Forest, woodlands, lakes, and proximity to McKelvey’s family. The corner location and community ties further reinforced their decision.

The need for more space became critical during the COVID-19 lockdown, when the family—parents and their two daughters, aged 11 and 8—found living in cramped quarters increasingly difficult. Gruenanger, an architect and founder of Space Group, identified excavation as the most viable solution, citing high property costs and the added expenses of moving and renovating elsewhere.

The resulting basement extension received a special commendation from the Royal Institute of British Architects (RIBA). The redesign includes a large sitting room, a double bedroom for their elder daughter, a gym, a laundry room concealed behind a revolving door, and ample storage solutions. Gruenanger emphasized that storage had been a problem for the family, and the new space also houses his extensive record collection.

The flat now features two bathrooms, and the couple chose not to add a bathroom in the basement extension to save costs and reduce maintenance. Gruenanger noted that an additional bathroom downstairs would have increased the project’s cost by about £20,000 and required complex water pumping arrangements.

The basement ceiling was designed with a height of approximately 3.1 meters at its highest point, achieved by excavating deeper than typical basements and incorporating skylights to prevent a claustrophobic feel.

Securing planning permission from Redbridge Council involved a six-month process, which included a basement impact assessment to evaluate risks such as flooding and structural integrity. With this project, Gruenanger and McKelvey have notably expanded their home’s footprint while maintaining their location and lifestyle in east London.