2014
London, United Kingdom

As part of a major refurbishment of The Royal Institution of Great Britain, careful consideration of how to waterproof the basement was required, critically the threat of water ingress had to be eliminated as the basement was to be partly used for archive storage. A Grade 4 waterproofing solution was therefore required. Sika®-1 pre-bagged waterproofing provided the perfect product.

A £22 million, two and a half year upgrade, the scheme was designed by architects Farrell & Partners and completed by main contractor ISG InteriorExterior Plc. An ambitious renovation of a 200 year old Georgian building, the project aimed to showcase the Royal Institution of Great Britain as the home of innovative and groundbreaking science that is still impacting our lives today.

Now complete, the project has created an extra 40% useable space within the building, which features a signature day-lit atrium, heritage exhibitions, public events, Time & Space café, a bar and a restaurant.

Project Requirements

To ensure the aged basement rooms were 100% watertight, specialist contractor Renderseal installed Sika renowned waterproofing Solution, Sika®-1, on the walls and floors. This was complemented with the Sika® Sikadur® Combiflex waterproof expansion joint at wall and floor junction.

Sika Solutions

Sika®-1 is a complete pre-bagged waterproofing system that Incorporates mortars and screeds, plus a specially developed admixture.

A colloidal silicate liquid, the Sika®-1 admixture is mixed into the system before the system is applied to the substrate. In the event of water ingress, the liquid reacts with the water by turning into a jelly-like substance, blocking all gaps and capillaries, and providing an impregnable and invisible seal.


Ideal for ageing basements, Sika®-1 bonds to the substrate. Once applied, it essentially becomes one with the structure and eliminates the threat of water ingress. Renderseal installed the Sika®-1 system throughout each of the 25 plus basements rooms, each located two levels below road level. To complete the waterproofing solution, Sika advanced jointing system, SikaDur® Combiflex, was also specified. A high performance joint sealing system, it provides proven protection from water ingress to all gaps between cracks, joints, panels and walls.


Certified by the British Board of Agrément (BB A), Sika®-1 meets the requirements of BS 8102 Grades two, three and four, with grade 4 being the highest recognised standard of waterproofing protection. On completion of the Sika waterproofing works, for additional peace of mind, Renderseal issued a full 10 year insurance backed guarantee.