Delta Membrane Systems has provided its Köster NB1 waterproofing slurry solution for a basement extension at a south London Mews Property. Basement excavations have proved particularly popular for London mews houses, as these properties are often located in conservation areas and are frequently bound by strict planning rules and regulations. Adding a basement extension provides the opportunity of adding extras living space such as additional family rooms, gyms, swimming pools, wine cellars, media rooms or functional spaces for storage and laundry.

The scope of the project was to sympathetically renovate an existing basement, by excavating the front drive to give a spacious below ground space to facilitate a gym area. The project required the newly extended/excavated basement to be made watertight with a waterproofing system which provides a Grade 3 waterproof environment (in accordance with Table 2 BS8102:2009). All basements should be constructed (or retrofitted) to cope with groundwater levels up to the full retained height of the basement. Waterproofing a basement preserves the integrity of a structure whilst ensuring the usefulness of the basement.

Delta’s Waterproofing Design Specialist suggested incorporating Köster NB1 to wall/floor joints (where the masonry walls meet the concrete slab). For external junctions, fillets were created using Köster Repair Mortar Plus (a unique expanding waterproof material) to keep important junctions protected and watertight. The coved fillets were further waterproofed using two coats of Köster NB1 crystallizing mineral waterproofing slurry. Insulation screed and further fillets were incorporated to create a robust waterproofing solution.

Detailing to the Type C Cavity Drainage System was refined, a standard set as standard by Delta Registered Installers. Both the property owner and main contactor were delighted with Advance Property Preservation Limited. The project was completed on time and within budget.