The White Collar Factory will be a mixed-use area of workspace, residential and retail, designed by architects, AHMM. The development, sited on London’s City Road, comprises a new 16-storey office tower, a new public square and refurbished existing buildings to the rear.
The new 2-storey basement has been waterproofed using a Type C system applied internally, to provide drained protection in accordance with BS 8102: 2009. The waterproofing system has been supplied by Triton Systems.
During demolition of the existing structure, the sub-contractor (Dunne Group) worked closely with Triton’s CSSW qualified technical team, to design the most appropriate and cost effective waterproofing system that was subsequently approved by all relevant parties as the most suitable protection against potential ground water ingress. 2,000 m2 of Platon P20 cavity drain membrane was subsequently specified for all earth retaining basement walls on both levels and the ground bearing slab at lower level. BBA certified Platon P20 membrane is a high capacity drainage membrane recommended for use where it is important to significantly reduce the risk of blockages behind the membrane caused by lime deposits.
Prior to the installation of the membrane, all fresh concrete at earth retaining elevations was treated with Triton’s Anti Lime solution. This treatment hardens and dust proofs the concrete as well as locks in free lime to further reduce the risk of blockages in the drainage elements of the system.
Any water entering the construction at upper and intermediate basement levels is gravity drained behind the studded P20 membrane down to a waterproof concrete bund/upstand which provides a 100mm cavity, onto which internal block walls can be built.
A series of 40mm holes at 900mm centres were drilled within the bund to allow any water to drain down behind the membrane installed to the walls at lower level. The bund was also waterproofed with Triton’s cold liquid applied TT Vapour Membrane (TTVM) that will prevent potential damp patches being visible on the internal block wall faces. A band of TTVM was also applied around the perimeter of the lower soffit dressing down behind the P20 membrane installed to the external walls and sealed with Triton Corner Strip (butyl tape).
In line with the requirements of BS 8102: 2009, removable panels were installed in the bund to allow access to flushing ports. These allow the system to be regularly maintained and flushed through to ensure a clear passage of water is maintained to the sump/pumps that are set within the lower floor slab.
Vertical joints in the Platon P20 were sealed using Platon Sealing Rope and Brick Plugs, with all wall/ floor junctions sealed using Platon Corner Strip Tape – a wider waterproof butyl tape. Platon Sealing Rope was used to seal joints in the P20 membrane that was loose laid to the floor slab.
Water draining from the system to the lower floor slab is drained via gulleys in the slab to the installed sumps. These gulleys also incorporate rodding eyes at approximately 12LM intervals to allow for maintenance of the system.
The P20 membrane on the floor has been screeded over ready to accept finishes and the construction of internal walls.