Case studies: Willowbeck Nursing Home

Sheffield – Refurbishment : Structural Waterproofing

Problem

Bosa Contracts Limited were commissioned by CNP in November 2005 to undertake investigation work into water penetration problems in a traditionally build nursing home which opened in 1999.

As the site was sloping the original design included concrete retaining walls, which formed the rear elevations of the upper and lower ground floors.

Investigation found that these retaining walls had been incorrectly treated on the internal face with a bitumen based sheet membrane system, which was lapped underneath the internal block walls and dressed approximately 1m onto the concrete floor slab to form an apron.

This waterproofing system was totally inadequate allowing water penetration through retaining walls and floor slabs resulting in water migration rising up internal walls and onto traditionally plastered surfaces to a height of 1.2m above finished floor level.

Solution

Bosa proposed the Sika 1 Structural Waterproofing system to project administrators CNP. This system stops water from entering the building but allows it to breath. It complies with BS8102:1990 Grade 3. In 2006 Bosa installed Sika 1 to approx 1750sqm of floors and 1700sqm of walls including 190m of Sikadur Combiflex to day and movement joints. Bosa Contracts Limited, the FMB Masterbond Warranty and Sika Ltd’s materials warranty have guaranteed the system for a period of 10years in line with other warranty schemes