Hello and thank you for your question. This is indeed an tricky situation and one must account for enough steel and concrete to accommodate the weight of a person sitting on the bench. The marble we used is 3/4" thick with a steel support pan underneath to hold the mortar. However, behind the wall, we added a large structural steel beam to account for the overturning force due to added weight on the bench. This is what holds the bench in place and gives the appearance of a clean edge underneath. An engineer should be able to assist you for further development. Good luck with your project!

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Amazing bathroom. Would it be possible to see a pic of the steel pan and beam detail for the bench? Containing that overturning moment is the key. What a great shower setup. What is the illuminated control in the shower? Thanks!

Thanks so much! As an engineer this appears to be a solid plan. Who manufactured the bench support pan? I would also assume two 16" center for steel supports.

John, thanks again for your questions. We don't have the exact manufacturer from that project but Innovis Corporation makes a product called Better-Bench. We would also recommend reaching out to your tile subcontractor or tile supplier and they might have some recommendations. Thanks again!