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Standing on a sizeable piece of land in a prosperous area of Chelsfield in Southeast London, a dilapidated bungalow was more than ready to be demolished and transformed into a 1,300 cubic metre excavation!
The clients of this particular project were looking to build their own spectacular 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.
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. But how would specialist contractor MJ Rooney Construction achieve this alongside a proposed basement gym, sauna, shower room and cinema?
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. Fortunately, the MJ Rooney team could bring their four decades of experience to bear, including in bespoke new-build basement design.
The project required significant groundworks before building
Wall ties were secured into the fixings for the cavity drain system
Inspection ports ensure it can be maintained in future
The extensive new-build concrete basement received a full cavity drain ‘Type C’ waterproofing system
MJ Rooney’s trained operatives installed the waterproofing
20mm floor membrane provides a high drainage capacity
The floor buildup included drainage channels adjacent to closed-cell insulation, covered by the 20mm floor membrane
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.
The finished basement houses a beautifully finished series of impressive rooms, protected by the robust and maintainable CDM System, in compliance with all industry standards.
The rear of the spectacular new property showcases the stunning work by the MJ Rooney team
The gym area in the new basement is completely dry and protected by the cavity drain waterproofing system
A luxury new basement cinema completes the space
The car lift delivers the covered parking required by the client
Our staff are able to provide guidance for projects of all sizes, whether you require some general advice about damp or waterproofing, or support with technical drawings and specifications.