QUESTION

Is Onyx slabs suitable for shower wall applications? Are there industry standards for Onyx slab installation? Are there performance standards for onyx slabs (specifically as shower walls)? Are onyx slabs a reasonable choice for shower walls?

ANSWER

ANSWER - Yes there are standards for the installation of onyx slabs, which are the same as the standards for marble. All geological classifications of stone have minimum/maximum values for their physical properties, and onyx falls under the ASTM C503 for marble.

Marble also has soundness classifications A, B, C, D. Although the classifications are really meant to reflect the characteristics of the stone encountered in fabricating, they generally refer to the class C and D marbles as fragile that may tend to have open fissures and voids, and wouldn't be recommended for shower applications.

Onyx is a chemical sedimentary precipitate stone that forms with water. So it should be suitable for a shower wall if it is installed correctly. Often the problems encountered with stone in showers is due to improper installation that subjects the stone to excessive moisture with other compounding deficiencies.