A not so clean slate

Barry Hunt (Independent Building Investigation Services Ltd, London, UK)

Structural Survey

ISSN: 0263-080X

Publication date: 1 December 2005



This is an initial attempt to classify natural roofing slate quality using the new European Standard BS EN 12326 and suggest how such classification may be employed to predict in‐service performance and identify potentially problematic materials.


A wide range of natural roofing slates has been subjected to the new standard testing regime and additional tests carried out. Experience of known in‐service performance and previous test results have also been taken into consideration.


An initial classification of natural roofing slate quality has been proposed with the flexural strength, water absorption, potential for oxidation and carbonate content considered to be the key components.

Research limitations/implications

There is considerable scope for refinement of the proposed classification by investigating the performance of the wide range of other natural roofing slates available and taking the results into consideration. Predicted in‐service performance is based on practical experience and can be considered only a general guide.

Practical implications

By classifying natural roofing slate quality users will be able to make better informed purchasing decisions based on cost versus quality. Slate producers, especially those with higher quality slates, will also be able to market their materials accordingly with less chance of losing out to lower quality, potentially problematic materials that still conform to the new standard.


The concept of a quality classification for natural roofing slate is not new, but this has been omitted during the creation of the new standard. The proposed classification is broader and probably better defined than those in existence elsewhere or previously used within the European Union member states.



Hunt, B. (2005), "A not so clean slate", Structural Survey, Vol. 23 No. 5, pp. 334-345. https://doi.org/10.1108/02630800510635083

Download as .RIS



Emerald Group Publishing Limited

Copyright © 2005, Emerald Group Publishing Limited

Please note you might not have access to this content

You may be able to access this content by login via Shibboleth, Open Athens or with your Emerald account.
If you would like to contact us about accessing this content, click the button and fill out the form.
To rent this content from Deepdyve, please click the button.