Retail Basement, Nottingham – Fixing Water Ingress with Oldroyd Cavity Drainage System
The basement, a retail space in Nottingham’s central Listergate shopping area, had suffered from problems with water ingress. As part of a £2.4 million refurbishment of the building, property consultants, King Sturge, and architects, Chapman Taylor, approached Safeguard to discuss the design of a suitable waterproofing system to upgrade the basement to a level of dryness suitable for a retail environment (BS 8102 – Grade 3).
Work Carried Out
The basement waterproofing works, which consisted of a combination of an Oldroyd cavity drainage system with Vandex cementitious waterproofing in specific areas, were carried out by specialist waterproofing contractor, Peter Cox.
Over 1100 m2 of high-profile Oldroyd Xv 20 cavity drainage membrane was used to cover the floor area and 750 m2 of Oldroyd Xv Clear cavity drainage membrane was used to line the walls. 600 linear metres of Oldroyd Aquadrain drainage channel were installed (mostly at the wall-floor junction around the perimeter of the basement, but also across the floor at regular intervals). These measures form part of a managed water disposal system and are designed to channel water entering the basement towards ten sump chambers containing dual assist pumps. Any water entering the sump chambers is discharged outside of the building by the pumps. The system is fully maintainable as “jetting points” are located at regular intervals around the Aquadrain channel and all the sump chambers are fully accessible through recessed manhole covers.
Some specific areas of the basement were better suited to waterproofing using the more traditional Vandex cementitious waterproofing system. These included the escalator pits which were waterproofed using Vandex Super and areas where steel joists penetrated the walls which were waterproofed using Vandex BB75 E. Approximately 150 m2 of Vandex BB75 was used on an earth retaining wall on the ground floor at the rear of the building where the presence of a concrete staircase made the use of a cavity drainage system impractical.
Creating a Dry Environment
The waterproofing system described above will prevent moisture from the ground entering the basement. However to achieve a Grade 3 environment (to BS 8102) levels of relative humidity in the air of the basement will need to be controlled. In this case this is achieved by means of the shop’s air conditioning system.