Exactly the process I was illustrating when I created the thread, “Do You Still Draw in 2D”, except in that case is was a spiral stair instead of a winder. I’d be curious what differences there are in the UK vs, the “International Residential Code” (a.k.a. IRC) which is USA only 
. If they have the same terms and parameters, it could be done as multinational with the right pull down menus, etc.