Structural Waterproofing - Project Profiles:
Asda Superstore

Project: New superstore for Asda Stores Limited
Location: Hamilton, Scotland
Architects: Percy Johnson, Marshall & Partners
Client: Asda Stores Limited
Main Contractor: GA Group
Engineers: Bielski & Partners
Concrete Works: Rainsway
Waterproofing: Preprufe® Waterproofing System (Preprufe® 300R & 160R)

This Asda store is designed with a 4 metre high concrete retaining wall on land with a potential gas problem. It is a sloping site serviced via a new roundabout on the main access to Hamilton.

This brownfield location is situated to the east of Hamilton and immediately adjacent to the M74 motorway linking Glasgow with the south.

The Challenge . . .

The engineer had been advised by his gas consultant to use a waterproofing membrane with appropriate gas resistance and a loose-laid, unbonded system had been incorporated in the drawings. Grace Servicised® has much previous experience with supermarket schemes including projects for Asda and Tesco. Because of this, the Hamilton project architects asked the Company to propose an alternative scheme, based upon products which would provide both gas resistance and tanking.

The Solution . . .

Following extensive consultations with the gas consultant, the engineers, the architect, the quantity surveyor and building control, a solution was submitted to the architect using Preprufe® 300 Pre-applied Membrane. Preprufe® 300 is a unique multi-layered HDPE membrane that forms an integral seal with wet concrete poured against it during the construction process. The membrane is then sealed to the structure it protects and not to the substrate.

Preprufe® 300 membrane is particularly suited for brownfield sites and overcomes many of the problems highlighted in BRE Report 212 Construction of New Buildings On Gas-contaminated Land.

Preprufe® 300 membrane is very robust and resists damage on site without additional protection. Its HDPE construction makes it resistant to the corrosive elements of landfill gas and leachate and its unique bond with the underside of the slab avoids problems arising from differential settlement of the subsoil beneath the slab.

Preprufe® 300 membrane is inherently waterproof, durable and chemically resistant with a methane permeability 40 times better than typical values for 1200g polyethylene - the BRE recommended minimum standard.