Riverstone is an first grade Argentinian slate that meets the highest classifications in the UK and the US, achieving A1-T1-S1 to BS EN 12326. The slate comes from the San Luis quarry in central Argentina and has the privilege of being accepted by English Heritage and Historic Scotland, the bodies responsible for the up-keep of buildings such as Buckingham Palace. The stunning profile of Riverstone slate adds a traditional and authentic look to a building, with Riverstone trusted as an alternative to indigenous materials. Riverstone slates are between 6-8mm thick and have a unique, rust-free warranty from manufacturer SSQ Slate. Riverstone also has a 100-year warranty that’s unique in the industry. This warranty shows that the life expectancy of Riverstone Argentinian slate is beyond 100 years and as such is more sustainable than other roofing tiles. Riverstone slate could outlast three or four other tiled roofs, increasing sustainability as Riverstone slate doesn’t need to be processed or synthetized which reduces CO2 emissions in the manufacturing process. Other benefits of this gorgeous natural slate include its low water absorption, allowing it to be installed in the harshest environments, bolstered somewhat by how the slate is cut. The slate is cut along the grain to give increased load resistance and contribute to its longer life. Riverstone Slate Specifications Dimensions: 500mm x 250mmThickness: 6-8mm Weight per m2: 43kgMinimum pitch: 22.5 degrees.Coverage: approximately 19.5 slates per m2 at 90mm headlap. Delivery Notes - Our slates are typically delivered on a six-wheeled lorry (11m long & 2.4m wide) with a tail-lift facility to offload on solid, level ground with a pump truck.Non-compliance to delivery restrictions may result in additional delivery charges. Should you specifically require a crane or small vehicle offload, please notify us at the time of placing the order, as an additional charge may be incurred. Please allow 5% extra in the ordered quantity to cover acceptable breakage in transporting natural slate products.