We will going to build long interior, round(little bit) shaped staircase (similar to this) from concrete, and I needed to get instructions with physics that it will possible to make it without any middle pillar that 12ft long staircase. So because of that We suppose to burrow the ground and concrete the base about 2-3ft tall where stair going to start.
I do not have particularly deep knowledge about staircase masonary. After a consulting mason, that he doesn't have a good alternative. If those solutions aren't reasonable, is there anything we can do that without making middle pillar?? How can we convince him??