Arklecrag

The Project – Early in 2019, we were challenged with re-roofing a block of apartments in Arklecrag, Washington, by one of our largest customers Engie. The structure was a 1970s three-storey building housing 65 apartments which remained fully occupied during the re-roofing works. The block was around 175LM in length bending at a 45-degree angle halfway. The existing roof covering was 450mm x 450mm Hardow Slates laid to 100mm headlap on battens and the old ‘cosy’ felt – A Bitumen felt with glass fibre insulation attached.

The Challenge – One roof slope was 9.8LM in length whilst the other was 4.6LM. After initial inspection, we noticed that wind-driven rain had breached the slates safety margin continuously and the secondary felt was the existing barrier keeping ingressive water out of the building. It was clear, a new improved specification was needed.

Other challenges included: unfavourable weather conditions, specific design requirements and time restraints.

The Solution – Due to the complexity and design we invited the slate manufacturer (Forticrete) to give their technical expertise on the project. They advised that a 600mm x 450mm Slate should be used, laid to 160mm headlap on the longest slope and 118mm headlap to the smaller rafter. The improved specification was accepted and agreed by both the main contractor and the housing association. Due to the building curvature, the inner slope became a large swept valley feature, with each Slate cut twice to ensure tight butted and continuous coursing. The convex outside scope was arranged with a similar design. The 2,500m^2 roof was stripped and renewed in an 18-week period which included several weeks of delays due to the inclnement weather. In addition, new fascias, soffitis and rainwater goods were installed to this scheme to ensure longevity and provide the finishing touch to complete the project.