This historic landmark on Leicester Square required revitalising so as to enhance its external appearance whilst maximising internal floorspace within the constraints of the existing retained Grade 2 listed facade. Make Architects produced a design which included the construction of a two-storey basement and adding an extra level to produce a mansard-style roof.
This requirement was for a flexible yet robust structural waterproofing design in accordance with BS8102:2009 which was supported by the appropriate design and system warranties. Premcrete was able to provide a design strategy within the budget constraints which exceeded the client’s requirements whilst ensuring the practicability of installation.
The waterproof layer beneath the basement slab incorporated a combination of a bentonite membrane and a crystalline cementitious coating to the top of the pile caps to provide complete protection. The risks associated with this deep basement structure demanded the use of a maintainable waterproofing system to manage any water ingress through the walls; therefore, a cavity drain membrane was installed to the thoroughly prepared secant pile basement wall with a jettable conduit installed at the base. Particular attention to detail was required to provide continuity where the new structure interfaces with the existing retained structure.
Hydroflow HP Cavity Drain
Levels below ground: