Starting with interior measurements and adding dimensions

[NemaTode]

Hi, I'm using SH3D for the first time and could use some help. All of my measurements are interior, and I'm trying to have all of the virtual walls accurate down to a 1/8". I'm running into problems adding dimensions when more than one dimension is starting at the same wall. I have keyed in the proper length of the wall, but I'm having problems lining up the walls so that the dimension measurement is the same as the wall length. How do I know when a wall is *exactly* lined up properly ? and with a dimension line?

Also, I didn't line up the "northwest" corner of the plan with the 0 coordinates on X and Y and now I really wish I had so that some of the wall measurements line up with the grid lines.

Thank you!

[Puybaret]

Maybe this video would help you achieve drawing your plan.

[NemaTode]

Puybaret, thanks for the reply and link.

I've learned a fair amount since I posted my question but I'm still unclear on how to precisely locate an interior wall. Specifying the length and width of walls is simple enough but what I can't seem to do is indicate that an interior wall must be, for example, 28" away from some other wall. As a hack, I've been creating dimension lines to manually measure the distance between various objects but is there not an easier way? The perimeter of my floor plan is half-filled with these manually-inserted dimension lines.
thanks.