Blue Brindle and Dark Heather clay tiles are a predominantly blue colour, with subtle shade differences of lighter blue and purple hues Properties Minimum pitch: 35 degrees.Size of tiles: 215mm x 165mm.Weight: 0.95kg.Material: etruria marl. Why Dreadnought tiles? Dreadnought Tiles are a British manufacturer based in Staffordshire where they have been manufacturing clay roof tiles using locally sourced Etruria Marl Clay for over 215 years. Etruria Marl (Staffordshire Clay) roofing products have unrivalled strength and durability (it is also used to make Staffordshire Blue Class A Engineering Bricks). All Dreadnought colours from blues, brindles and browns to reds are generated without the use of artificial stains or coloured sands; instead the colours are the product of careful control of the kiln atmosphere. This natural quality, which creates subtle colour variation within each tile, gives a unique quality to the Dreadnought product that enhances the appearance of any roof.