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  • What it means

    CE marking applies to many products sold or used within the European Economic Area. It is a declaration by the manufacturer that the product meets the requirements of any relevant European Directives.

    Products used for building and construction work are covered by the European Construction Products Directive. This specifies that roofing slate must comply with a European Standard, EN 12326* and, if it does so, it qualifies for a CE marking.

    In the UK, the Building Regulations specify that if a British or European Standard exists for a construction product, these standards must be complied with. As a result, only roofing slate tested to EN 12326, and therefore carrying a CE marking, can be used.

    *This European Standard has been adopted by the UK as a British Standard, BS EN 12326, and supersedes other British Standards relating to these products.


    European standard

    EN 12326 ensures that all roofing slates sold throughout Europe are tested in the same way, using the same methodology, regardless of their origin. Providing they meet some very basic requirements, they then qualify for a CE marking which means they can be used for building work within the UK.

    However, the fact that they’ve been tested and have received a CE Marking does not give an indication of their relative quality or likely performance in use – this can be assessed by interpreting the results of the EN 12326 tests.

    This test information has to be provided with the slates and appear on a test certificate.

    Understanding the results – what makes a good slate?

    Providing you understand the significance of the various tests and know what to look for, making a good, considered judgement is relatively straightforward.

    The notes against the test certificate below show what to look for to be able to tell the difference between a great slate, a mediocre one and an inferior slate. If a test certificate isn’t available then it’s best to play safe and reject the slates: apart from not knowing what you’re buying or where from, you may be falling foul of the law by buying slates that haven’t been tested and don’t qualify for a CE Marking.

    Although the format of the test certificate and crate label varies from company to company, the same information should appear as it reports the results of a specific set of tests.


    Carbon footprint

    Embodied carbon refers to carbon dioxide emitted during the manufacture, transport and construction of building materials, together with the end of life emissions. This is an accounting method which aims to find the sum total of the energy necessary for an entire product life-cycle.

    The carbon footprint of natural roofing slate is lower than that of clay and concrete tiles and fibre cement slates.  This is due to it being a natural product and the absence of a manufacturing process.

    This is particularly interesting and important to specifiers and architects for example who have to create buildings with lower carbon footprints, in-line with current legislation. For more information on the carbon footprint of slate compared to other materials, visit our carbon page here.


    Example pallet label

    Layout 1


    Example label notes

    The following notes refer to JRC’s Slate Test certificate as seen on the sample above:

    ① The CE marking. This shows that the product complies with the relevant European Directive which, in the case of roofing slate, means that it’s been tested in accordance with EN 12326.

    ② The address of the supplier.

    ③ The date the tests were carried out. Note: EN 12326 specifies that roofing slate s tested every year, or for every 25,000 tonnes of finished material – whichever is sooner – unless production is under 5,000 tonnes per year. If production is under 5,000 tonnes per year then it must be tested every 3 years, or every 5,000 tonnes of production – whichever is sooner.

    ④ The European Standard that the product has been tested to.

    ⑤ The products the standard refers to.

    ⑥ Confirmation that the roofing slates meet the dimensions advertised by the manufacturer and are within the tolerances stated.

    ⑦ Confirmation that the roofing slates meet the nominal thickness advertised by the manufacturer.

    ⑧ This indicates the strength of the slates. Samples are put under load until they break, the data being used to calculate the Modulus of Rupture (MoR) both across their width and along their length. The Modulus of Rapture test is also used to calculate the lower expected strength value which is then used to calculate the minimum thickness of the slate.

    ⑨ This gives an indication of the amount of carbonate in the slate. There are three classifications: up to 5% / 5-20% / over 20% – generally the lower the figure, the better the slate.

    ⑩ This gives an indication of the rock’s water absorbency and how a slate may react when wet. Values up to 0.6% are classed as W1; values over 0.6% are classed as W2.

    ⑪ The Freeze / Thaw Test is only carried out if the slate is graded A2 in the Water Absorption Test. The test tries to predict the loss of strength caused as water in the slates freezes, damaging its structure. A2 roofing slates are potentially a high risk in the UK.

    ⑫ The Thermal Cycle Test relates to the stability of any pyrite in the slate, predicting its reaction and whether it will oxidise (rust). There are three classifications – T1 / T2 / T3 – which indicate the extent of the damage this may cause to the slate. T1 denotes that there is no reaction or that there are colour changes that do not form runs of discolouration nor affect the structure of the slate. T2 indicates that colour runs may develop and T3 indicates potential structural damage may result from the pyrite oxidising.

    ⑬ The Sulphur Dioxide Test indicates how the slate will perform in an acidic environment, which is more typical in cities. Acidic deposition can dissolve carbonate in the slate causing material loss and structural weakness. Slate with a carbonate content of up to 20% is classified as either S1 / S2 / S3, a result that directly affects the thicknesses of the roofing slate that can be produced. Slates with a carbonate content above 20% are tested in a different way and should be considered as probably not fit for purpose.

    ⑭ This indicates the amount of carbon in non-carbonate form that’s present in the slate e.g. graphite, oil and other organic matter. The standard stipulates a maximum limit of 2% so the lower the percentage beneath this the better.

    ⑮ Possibility of the release of dangerous substances.

    ⑯ Compliance with external fire performance factors.

    ⑰ Grading of reaction to fire.


    Further Information

    If you have any further questions about CE markings, or anything else across our site, feel free to get in touch with us on 0333 011 7900.

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