Leicester Square

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.