engineering drawings

huangyhg

engineering drawings
what linetype and lineweight would you for an existing structure?  for plan work and details, i use a shaded (grayscale at 50%) for the existing structure and the new modifications/new structure will be regular solid lineweight.  the linetype for existing plan work is a short dash and for existing in details we use a dash double dot.  
what do you use for demolition?  we use the structural components not to be demolished as the same as existing structure and the structural components to be demolished are bold and dashed.
what do you use for existing and demolition and what is the typical convention for existing and demolition?

we do what you do but for detail we just use the existing line as light straight color instead of dashed.
we do not put the demolition line on our structural.  we figure they can see it on the archtectural drawing.  we just put the new lines and the existing lines that stay.   
i typically use a thin line for the existing, a dashed heavy line for the demolition, and a heavy line for new, so that you can clearly see the difference.  otherwise, lots of notes to plan what the lines mean.
don phillips
existing lines are lighter and dashed or phantom or something like that, so they are obvious to me when i am working in the drawing. demolition would also be lighter with a different dashing type from the existing to remain. some people get all in a wad about this kind of stuff and overlook important structural aspects that could actually cause a collapse. i just try to be consistent in my line types and have overall pretty good looking drawings.
he was a wise man who invented beer.
--plato
we use half-tone lines for existing.  you just need to be careful because sometimes the prints come in too light and you can hardly see the half-tone.  phantom lines work fine too.
the key here is to simply be clear in what you are "telling" the contractor.
keep in mind that the "work" of the project is what you note, not necessarily what you draw.
the required work represented by your plans should be described by:
   a series of notes with linework which supports and clarifies the notes.
and not by:
   a series of lines with a few notes to clarify the lines.