I've done a little work with tiles in inkscape on my House Map.

I have had good luck drawing pieces like door and stairwell symbols extra large, then shrinking them down. After I build the symbol I will bound it with a square or rectangular bounding box that I then set the fill and stroke to unset then group the whole thing together. This way I can get it to snap into my grid when I shrink it down. A bit of math to figure out what the stroke widths need to be so they are visible when you shrink the whole thing down.

I may put together a pack of them if I keep using them.