Class and Durability
As a natural product, limestone requires knowledge and understanding. Density, finish and
how a stone is quarried all influence the final selection. The most common misconception
about limestone is that it’s a soft stone. In reality, limestone can range from very hard to
very soft. It should be chosen specifically for how it will be used in the final design, while
taking aesthetic preferences into account.
A few benefits of limestone include:
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Durability
Temperature and humidity control
Better traction and less porosity than many other stones
Neutral color and tones complement bold architectural features
Easy to clean and maintain
ASTM International (formerly the American Society for Testing and Materials) classifies
limestone in three categories1:
Class I – Light Duty. Soft limestone best used for dimensional, thick cladding and carving.
Most buildings in Paris use these types of stone.
Class II – Medium Duty. These stones can be used in cladding and residential flooring, as
well as bath applications.
Class III – Heavy Duty. The French call this limestone « Pierres Marbrières », or literally,
marble-like limestone. Comparable in hardness and porosity to harder marbles, these stones
can be used in heavy commercial traffic applications (such as flooring) and kitchen
countertops.
Getting it Right. A good example of how the right stone was chosen for the right building
application is Le Louvre in Paris. While the original building was built with a soft limestone,
Saint Maximin, the new extension interior is clad in a medium duty stone, Magny Doré. Also,
its new interior flooring has a heavy duty limestone from the Chassagne quarry in France and
able to withstand the foot traffic of 8 million visitors a year.
(1)
ASTM Designation: C 568 – 03, Standard Specification for Limestone Dimension Stone