Can't close Surfaces into a solid, can anyone help?

Hello, everyone!

I am designing a staircase using surfaces, when I try to join all the surfaces to form a solid something goes wrong and one point shows as a naked edge.
I tried everything I know, creating new surfaces from adjacent edges, patching, matching surfaces…, but this point always remains opened.

I must have a solid object to import in Revit or Autocad3D for the guys manufacturing the concrete forms, they asked for surfaces, not meshes.

Can anyone help me? Thanks in advance!
B170_S04_R00_v05_ramp-only_part2.3dm (2.4 MB)

Hello - this has one of those pesky ‘point’ edges that won’t close. Use the command

RemoveAllNakedMicroEdges on this.

-Pascal

Thank you very much, Pascal!! that did the trick, didn’t know about this command.