Split landing area of stair

[Anonymous]

I am drawing a triangle form stair, I wonder if I can split part of the area of the landing space, because of its triangular shape.
I tried to use the split tool, but it doesn't work.
Regards

[Laszlo Nagy]

You can select and edit the Stair Boundary to any polygonal shape:

https://www.youtube.com/watch?v=IYv7AF4fM2c&index=5&list=PLnXY6vLUwlWWIb70Jj3kq1o4dY9ZVuEWh