500mm x 250mm Contessa 1st Quality Natural Roofing Slate ~ Blue / Grey

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Product code: CEM0011

Estimated delivery: 3 - 5 Days

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£1.28 inc vat £1.07ex vat

500mm x 250mm Contessa 1st Quality Natural Roofing Slate ~ Blue / Grey

Pre-holed Natural Spanish Slate

Contessa slate is a tough natural material and samples are regularly tested to the following national standards:
British Standard
BS EN 12326-1:2004 Product specification for roofing slate
• Exhibited the top Class A1 for water absorbtion
• Exhibited the top Class T1 for thermal cycle resistance
• Exhibited the top Class S1 for sulphur dioxide exposure resistance
• Good flexural strength both transversely and longitudinally
• Acceptable non-carbonate content
Oxidisation
There is a potential oxidisation risk with all Contessa slates as their colour is determined by the presence of iron compounds and finely divided carbonaceous matter. They also generally have more pyrite, which may or may not be visible on the surface of the slate. Surface oxidisation of these metallic minerals may cause discolouration or staining of the slate. This characteristic is permitted within the T1 classification.
Standard grade slates with a T2 classification may also discolour and stain slates in the courses below (please refer to table 3 of EN12326-1:2004). Neither discolouration nor staining from oxidisation run off will affect the weatherproof performance of the roof.
Slate Grain and Surface Characteristics
Most slates have a secondary plane of cleavage or grain which can only be determined microscopically. However this grain should not be confused with the texture which can be seen on the surface of the slate which is influenced by the direction in which the slate is split with a chisel, either from the top or the side.
Contessa slate has a normal texture using the classifications detailed in BS EN 12326.