Easiest way is via the Width Tool.
Simply use the Width Tool and Option/Alt click at the ends of the path and drag the width marker up to the path. This creates the stroke on one side of the path:
Once you do this you can save the Stroke Profile:
Then applying it is as easy as selecting the profile in the Stroke Panel or Control Bar.
Illustrator inherently centers strokes on all open paths. There's no other way to offest a stroke that I'm aware of.
I don't think Photoshop is the right tool for the job.
Neither is Illustrator, frankly. Yes, you can tediously do floorplans with it. But why would you choose for that purpose a program which provides no user-defined drawing scale, no dimension tools, no callout tools, and no proper arc tool?
I know Illustrator is no CAD program but I don't think I'm asking too much from it.
Corel Draw, Corel Designer, or Deneba Canvas would all be more capable for your stated purpose. All three provide the features mentioned above. Canvas has CAD-like accuracy and includes drafting-industry drawing standards. Corel Designer is almost identical to Draw in user-interface, with additional technical drawing features and robust CAD imports, including abilities to import, orient and flatten 3D models.
Thank you for the suggestions.
CorelDRAW and overall other Corel products are out of my list. I just hate their approach, starting on the bloatware (man, it has more bloatware than old HP drivers). I don't think it's worth a discussion, for preferences and personal reasons I'm not going to consider Corel products.
That Canvas software seems really good (although it's strange and a little funny that their site reads "AC/DC" hehe) I don't think how easy it is to print though, you know, I used to use Inkscape in the past and it was really a pain to print my creations, the local prints shops will refuse to print in the native svg format, even exporting to the standard SVG, the other programs don't read it correctly, and exporting to PDF rips out all the effects, exporting to bitmaps just doesn't print very well (sharp lines), in the end I had to use an international printing service to print my drawings in Inkscape, what's really a pain. The local print shops only work with AI and CorelDRAW files, plus some of them can print PDF, yes, I know this doesn't seem professional stuff, but I can't do anything about it. So, I wonder if they will be able to print the Canvas' files, maybe if there's a way to export to AI or CDR files, or PDF at least...
Anyway, so far I'm quite happy with Ilustrator but I'm going to download Canvas to take a look at it, I didn't know AI didn't have those mentioned features, that really sucks imho, I mean, I think they're basic features even for an artistic program, specialy one that has like 30 years of development.
From a price standpoint, all of these programs are within the limits of my budget, I'm not really saving money to get the best software for productivity.
Thank you .
Just a little update:
I've downloaded and tried Canvas but I really didn't like the interface, the first problems are the inverted zoom and the zoom stepping that I couldn't find a way to configure, there should be a way but it's fairly well hidden somewhere.
However, it doesn't have a lot of graphical effects, and that's a dealbreaker for me, I'm going to make artistic, colorful, fancy, and overloaded in effects floor plans, I don't need really much CAD tools, about the arcs, It's easy enough to make any type of arc using circles and pathfinder, plus the smart snapping really comes handy, It may not be the 100% perfect tool for the job, but ihmo it's good enough. Plus everything seems familiar to me, snaps, effects, the inteface, everything is 'photoshopey'. A dimension tool would be useful, but it's no big deal because it's easy enough to do it manually and it's only a little part of the work (<5% i guess) so it's okay.
So far I'm sticking with AI but I really appreciate recommendations.