Speeddeck’s flexibility demonstrates offsite is’nt always best

Arrico Roofing Ltd has used SpeedDeck's onsite roof manufacturing expertise to deliver a design by specialist architects Ashton Smith Associates for Tesco's first 'dot com' warehouse in Maidstone, Kent. Offsite methods were simply not viable for the demanding nature of the site, so Arrico turned to SpeedDeck for help.

Due to the complexity of the Priory Park site where Tesco's new warehouse is located, combined with the design for the roofing, which required 90m long uninterrupted sheets, delivery of the finished product from offsite was impossible. This presented Arrico Roofing with only one solution: the roof needed to be manufactured onsite at eaves level.

Following a comprehensive onsite risk assessment, the SpeedDeck solution involved a 160 tonne crane located 10m away from the building to suspend the onsite rolling machine at the eaves level, thus avoiding the incumbent canopy. This enabled the 250 sheets of SpeedDeck in 0.6mm Corus Colorcoat HPS200® Moorland Green steel to be rolled directly onto the roof.

The resulting roof achieves a 'U' value = 0.25W/m²K, gives a sound reduction of Rw = 45dB and has Corus Confidex guarantee cover for 30 years.

The location and design of the building meant that the onsite method delivered by SpeedDeck was the only option. Covering an area of almost 11,000sqm, the building is 120m long and 90m wide. Its roof is 11m above the ground, but due to the location and design of the building, Arrico had to engineer a solution to get the 90m long sheets to roof level. Because Tesco's warehouse is located at the very corner of the site, access to the roof was only possible from one side. This was complicated still further by a canopy that projects 9m and runs the whole length of the building.

Due to the nature of the location, Ashton Smith Associates had to design the building with a gradually curving barrel-vaulted roof in order to ensure it remained in keeping with the surrounding buildings. With a pitch of just 4˚ at the eaves and a smoothly curving vault with a 640m radius, there could be no risk of end laps or visible fixings to compromise the weather-tightness of the roof.

Although there were three possible installation options, it became clear from the nature of the site that only one was going to be viable: There was no room to ramp roll the coils, due to the presence of the canopy and the lack of ground space available on the site. Another alternative considered was to use a lifting beam to get the sheets up to roof height, but no beam would have been long enough to accommodate the 90m sheets which were the only option due to the barrel vault roof design.

Gavin Harriman, Director of Arrico Roofing said, “We knew SpeedDeck had the ability to roll its products at eaves height, so we placed the order with them before the technical team even saw the site. Working with eight to ten men on the roof at one time, it took SpeedDeck just four days to roll the roof from the manufacturing unit with the crane working from only three positions along the length of the building. The whole installation was complete in less than two weeks.”