Although not extraordinary from a design point of view, Primark’s 56,000m2 warehouse roof posed challenges in terms of its sheer scale. A new 25-year lease was due to be signed on the centre but the existing roof, which comprises five 300m-long ridges, was in dire need of replacement.
The location is very exposed and the roof had suffered from extensive wind damage and the laps and joints were starting to fail. Removal and replacement was deemed too expensive, so an overlay solution was considered the better option. The roof receives little foot traffic and very few services, so we felt a single ply membrane was the ideal application.
Thermofol PVC is designed to withstand climatic extremes and temperature shocks and Bauder was able to work with us on the design, carrying out wind uplift calculations and various pull tests to trial the type and number of fixings required on the perimeter detailing.
Bauder’s single ply is able to retain cold-bending flexibility at less than -30oC without losing its elasticity, it is easy to install and weld, and has a high tensile strength of more than 1,100N, achieved thanks to a high-quality polyester reinforcement within the membrane that is designed to resist tears and punctures.
The system is mechanically fastened to the deck using automatic trolley welding machines and hand-held welding guns for detailing. It is very fast to apply and we were able to lay up to 1,500m2 a day, depending on the weather.
Bauder’s product guarantees also run back to back with its contractors and incorporate labour and materials, which was very reassuring for Primark. The new roof structure is expected to last 25 years.