EN 12326 &
CE Marking
The European Standard EN 12326 is part of a series of product standards for building materials and specifies the requirements for roofing slate products.
It is published in two parts:
- Part 1: Product specifications
- and Part 2: Test methods.
As a whole, this standard sets out the specifications to be met by natural roofing slate based on the results of a number of type tests. A broad range of parameters are tested, but the three most critical areas are Thermal Cycle, Sulphur Dioxide Exposure and Water Absorption.
Thermal Cycle
Essentially, this process assesses the levels of rust or oxidization within the slate.
The test involves repeatedly immersing six pieces of slate in water and then drying them out for up to three weeks. The samples are then inspected for corrosion and the results are classified as follows:
- T1: No apparent change or some surface rust or other color changes that neither affect the structure, nor form runs of discoloration.
- T2: Oxidation or appearance changes of the metallic inclusions with runs of discoloration but without structural changes.
- T3: Oxidation or appearance of changes of metallic minerals that penetrate the slate and risk forming holes.
Sulphur Dioxide Exposure
Sulphur Dioxide Exposure
The slate samples are placed in a hermetically sealed container for up to three weeks and subjected to extreme acidic and humid atmospheric conditions. These samples are then subjected to a standardized mechanical scraping test to measure any softness caused by the chemical disintegration of any carbonate content. Results are shown as S1 (no change), S2 (the slate must be split at least 5% thicker) or S3 (slates must be at least 8 mm).
Slates containing more than 2% carbonate content are not suitable for roofing or external cladding.
Slates containing more than 2% carbonate content are not suitable for roofing or external cladding.
Water Absorption
Excessive water absorption will result in natural slate being vulnerable to frost damage.
If the slate absorbs 0.6% or less of its mass in water, it is classified as W1, the highest grade, and needs no further testing.
If the absorption is greater than 0.6% it is classified as W2 and must be subjected to a separate freeze-thaw test, showing no deterioration in mechanical strength.
If the absorption is greater than 0.6% it is classified as W2 and must be subjected to a separate freeze-thaw test, showing no deterioration in mechanical strength.
