Summary

Newton waterproofing products were used to waterproof the basement garage, car lift, gym and cinema for a luxurious 4-storey new-build residential property in a prosperous area of Chelsfield in south east London.

Context

Standing on a sizeable piece of land in World's End Lane, a dilapidated bungalow was ready to be demolished and transformed into a 1,300m3 excavation. The clients wanted to build their own four-storey Georgian-style property on the land. This included a requirement for sheltered parking, however with planning restrictions in place, some creative thinking was needed to accommodate this in the design.

Planning restrictions

Whilst the footprint of the building was already large enough to accommodate a sizeable 260m2 basement, planning restrictions prohibited how far back the property could sit. With so much basement space available, the design therefore incorporated a car lift and underground garage into the above-ground and below-ground specification. Specialist contractor MJ Rooney needed to achieve this alongside a proposed basement gym, sauna, shower room and cinema.

Project scope

To deliver the multipurpose basement and its different needs, the 260m2 area was divided into an ‘external’ space for the car lift and garage, and an ‘internal’ space for the gym, sauna, shower and cinema. Both areas also needed to be completely dry, defined as a Grade 3 environment by BS 8102:2022.

Solution

To achieve the Grade 3 environment, the waterproofing solution needed to be fully continuous and maintainable.

The primary waterproofing solution was a full internal cavity drain system utilising the Newton CDM System.

To achieve this, the 8mm 508 membrane was installed to all walls with specialist CDM Multiplug fixings. Across the floor, the 20mm-deep 520 eco Floor membrane provided a high drainage capacity, sealed to a high-load DPC with CDM OverTape to provide continuity through the internal walls.

Beneath the floor membrane Fibran XPS 500-C delivered an insulated build up, also creating the perfect 50mm space for a perimeter drainage system using CDM BaseDrain.

Finally, the drainage system was connected to a Titan-Pro sump chamber with dual pumps for reliable water removal.

A separate Trojan-Pro sump chamber was also used to remove foul water from the toilet, sink and shower in the gym area.

Products supplied

  • CDM System - a comprehensive Type C waterproofing system that will usually be suggested when looking for superior levels of protection against water ingress

  • 508 Membrane - BBA-approved, high-quality 8mm cavity drain membrane for use within the Newton CDM System

  • 520 eco Floor Membrane - BBA-approved, 100% recycled, 20mm deep cavity drain floor membrane delivering high drainage capacity

  • Fibran XPS 500-C - 50mm deep, closed-cell thermal insulation board made from rigid extruded polystyrene foam (XPS)

  • CDM BaseDrain - drainage system used with the CDM System to receive water ingress and discharge it to a pump system or drainage

  • Titan-Pro pump system - unique and specialist sump and pump system, specifically designed for use with the Newton CDM System

  • Trojan-Pro sump chamber - multipurpose sump system suitable for lifting sewage or removing ground and surface water

Result

The finished basement houses a series of impressive rooms, protected by the robust and maintainable CDM System, in compliance with all industry standards.