Unit Precision in Revit

[rdaniel]

What precision do you draw to in Revit?

[jameswest77]

What precision do you draw to in Revit?

1mm. What do you mean? Why would you be less than 100% accurate?

[rdaniel]

That's my thought. I've always drawn to 1/256", even though dimensions are held to (not rounded to) 1/8". Just checking to see if there are other schools of thought out there.

[jameswest77]

That's my thought. I've always drawn to 1/256", even though dimensions are held to (not rounded to) 1/8". Just checking to see if there are other schools of thought out there.

now don't get me started on why things can't be moved small distances in Revit, like less than a millimeter. (Element is too small on screen) Its CAD for bloody sake, how can anything be "too small" Grr...

[richardarchitect]

now don't get me started on why things can't be moved small distances in Revit, like less than a millimeter. (Element is too small on screen) Its CAD for bloody sake, how can anything be "too small" Grr...

I couldn't agree more James. I've been running up against this constantly while trying to create 3/32" generic annotations in revit. Just because my units are set to 1/256" doesn't mean I can draw a line 1/256". In fact I can only draw a line 1/32" long.

I finally created the attached annotation to the NFPA 170 standard by drawing it in AutoCad, importing it, then fussing with it for another few hours until it looked reasonable. Perhaps i'm missing something, but I've explored every possibility I can think of.

[patricks]

We always keep units set to 1/256" so that anything out-of-whack is easy to spot. We also try our best to keep everything on even whole inch dimensions. We don't like fractions here! Occasionally we'll have a 1/2" or 1/4" dimension, but pretty much never a 1/8" dimension. Things just do not get built that precisely in the field.

Yes I know there are building materials with 1/8's and 1/16's (3 5/8" studs, 5/8" gyp, 7/16" OSB, etc) so we always try to dimension to the face of stud and/or edge of slab for exterior walls and block walls, and to the center of stud for interior stud walls.

[rdaniel]

Yeah, when working with masonry (especially CMU backups), 1/8" precision is a must. Steel is expected to be built to 1/6" precision, the structural engineers I have worked with maintain this tolerance in their documents. Whether it gets installed that way or not, I don't know for sure.

[tomnewsom]

For existing buildings, I try and model to within 5-10mm of the survey.

For new works, it's exactly what it says it is. Dimensions to 1mm.