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Our Lady’s Convent High School, Hackney


This voluntary-aided school in Hackney is part of the BSF programme. RIW were asked to advise on waterproofing in the early stages of the design process by Jestico + Whiles.

Architect: Jestico + Whiles
Main Contractor: Wilmott Dixon
Principle Application: Internal Tanking
Products Used: RIW Cavity DrainRIW Sheetseal 226RIW Toughseal, RIW CementsealRIW Flexiseal

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The Challenge

This four storey new build project is on a compact, stepped site which tested the continuity of the waterproofing strategy. The numerous interfaces and changes in level needed careful consideration, then bespoke waterproofing solutions were proposed for the different substrate materials, from concrete in the ground rising to a steel main frame with a secondary frame faced with cement boarding. Therefore an isometric study was required to visualise the proposed strategy.

The Solution

A range of different RIW products were used to accommodate the various changes in levels and to manage the differing movement capability at each of the structural interfaces. A combination of RIW Cavity Drain solutions were recommended for the walls of the partial basement, along with RIW Sheetseal 226 across the slab. RIW Cavity Drain allowed water to be directed away from internal finishes to a maintainable land drain below the structure.

As the building rose out of the ground, the waterproofing strategy had to adapt to maintain continuity as both the structure and the retaining walls were stepped. Both RIW Toughseal and RIW Sheetseal 226 were used to continue the waterproofing to the required level above ground. RIW Flexiseal was used on the entrance podium to provide waterproofing over the basement, and RIW Cementseal maintained continuity at isolated pad locations below the basement slab. This combination of products resulted in an effective and single sourced, total waterproofing solution. 

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