You can also find a brief description at https://www.whisstock.com/realcadd/page ... tool_id=10
Scroll down to the section "Parallels – Static". The fourth "Tip" : Making Walls
You can draw from the left or right instead of the middle by specifying one distance as 0 and the other the full width of the wall. Also note that the "middle" doesn't have to be the centre of the wall – you can specify different distances left and right.
This also works with other tools – Rectangle, Oval, Polygons etc., though I don't think I mentioned it in the manual. With Polygons you can't use the Control key to delete the middle line because you have to do a double-click to finish the polygon – so you have to delete the middle line once you're done.
A double rectangle for example would give you a rectangular room, or house, with walls the specified thickness. Or the Polygon tool can give you complex walls, specially if you set up a series of Snap points first.
To tidy up the joins use the Cut and extend tool (keystroke U) or the Cutting tool (keystroke M). If you draw walls with the Polygon tool the joins will be cleaned up as you draw. If you draw using Rectangles or Polygons, you can convert the results to plain lines (to edit them etc.) with the Action >> Convert to lines menu item.
You can draw any number of parallel objects this way by specifying the number in the Parallels window – so you could have, say three lines one side of your middle line and two the other – not sure this is very useful however!
When I update the manual for v.5, I will add a better description of using Parallels in conjunction with other tools to make walls.
Cheers -- George