City Hospital, Belfast – Waterproofing Underground Car Park

Background

The distinctive 15-storey tower block of the Belfast City Hospital dominates the Belfast skyline. It was completed in 1986 and is currently the largest general hospital in the United Kingdom.

One of the hospital’s multi-storey car parks was suffering from water ingress in it’s below ground areas – causing localised flooding. Specialist waterproofing contractors, Toner Damp-Proofing, were called in to investigate the problem.

Investigation

The car park had been constructed in the late 1990s and its original waterproofing system had failed.

Because the original waterproofing system had been applied to the outside of the car-park’s retaining wall and then backfilled it was not practical or economical to access it for repair.

The Solution

The client wanted the basement areas of the car park to be waterproofed to provide a Grade 2 environment as defined in BS 8102 [1] – i.e. a waterproofing system that would prevent all water ingress.

An internally installed Vandex cementitious waterproofing system was proposed. This would allow the waterproofing to be installed without the need to excavate around the basement area. It would also make access easy if repair should be necessary in the future (a key consideration highlighted in BS 8102).

[1] BS 8102:2009 “Code of practice for protection of below ground structures against water from the ground”.

Installation

Concrete block walls were stripped prior to treatment and the floor screed was lifted. Surfaces were then vacuumed and prepared to accept the Vandex waterproofing system.

A Vandex Unimortar 1 fillet was installed at the wall-floor junction around the perimeter of the basement area to provide additional protection to the construction joint between the wall and the floor.

A 3:1 sand:cement render coat was applied to the walls to provide an even surface on which to apply the Vandex BB75 waterproofing slurry. The Vandex BB75 was applied by trowel the next day and allowed to cure. On the third day, a 3:1 sand:cement finishing coat was applied.

Vandex BB75 waterproofing slurry was also applied to the floor (following surface preparation). A screed was then poured on top.