Quality Control

All Primera Finest Natural Slate passes stringent testing before being added to our supply chain.

Until the early 2000s, natural slate for roofing in the UK was covered by the quality assurance testing specification BS 680-2:1971. Initially compiled in 1944 when the only slates available in the UK were of British origin it included 3 simple pass/fail tests.

The test did not require proof of origin or identification of samples, there were no regular repeat tests or minimum number of samples to be provided. A number of well-known ‘craftsmen’ controlled the slate supply. Their knowledge of both the slate and the British climate, coupled with their name, guaranteed the quality.

A rapid growth in international trade in roofing slate since the 1980s, primarily from Spain, has forced a change to the testing of slate. Indigenous industries still exist in the traditional European slating regions, such as Wales, alongside the imported Spanish product.

Present regulation requires slate to be tested to EN 12326 standards. The EN 12326 is based on a classification system where the onus is on the user to select a slate of the appropriate quality for their project and locality.

There are a number of obligatory requirements. These are:

  1. Slate packaging must display a valid CE mark
  2. Slate labelling must include the prescribed mechanical and performance data
  3. Slate labelling must identify the origin of the product
  4. Slate thickness variations
  5. Comprehensive test data required by the standard must be available on “accompanying commercial documents”
  6. Petrographic testing must be undertaken annually
  7. Assessment of dimensions to ensure that no more than 4% of slates are outside dimensional tolerances
  8. Other performance testing to be undertaken every 25,000 tonnes of production or annually, whichever is sooner