Sukkah on a balcony with a stone wall

I have a balcony with a stone step around it. Its height is 39 cm, and its width is 38 cm. At the far end of the stone step there is an iron railing. My question is, can I put the wall of the sukkah next to the railing at the far end of the stone step, or do I need to fix something here? The problem is that the wall of the sukkah doesn’t reach its floor, and the stone step is used for sitting, it doesn’t fulfill the role of a wall.  

Your sukkah is kosher and you are permitted to sit on the stone step. But you do have to make sure that the height of the wall of the sukkah is more than 10 handbreadths over the step.

We consider the stone step to be a part of the floor of the sukkah, as if the floor was at two levels. Therefore, there is no problem of the wall being more than three handbreadths above the ground of the sukkah. This wall is close to the stone step, which is the continuation of the floor of the sukkah. For the same reason, we don’t have the problem of the wall being at a distance of more than three handbreadths from the end of the floor of the sukkah (in horizontal direction). Because the step is considered as part of the floor, the wall of the sukkah is now right next to its floor.

There are some Rabbis, however, who take a more stringent view of this. According to their opinion, one has to attach the plywood wall to the closer end of the stone step, and it has to be at a height of less than three handbreadths from the floor of the balcony.   

Responsa “Dvar Shmuel”, chapter 203; Responsa of the Ramaz, chapter 30; Shaarei Tshuva, ch. 634; Kaf Ha-Chaim, ch. 634