https://forums.autodesk.com/t5/revit-mep-forum/duct-lining-serious-issue/m-p/5666256#M75396 <P>1. Yes, that is what we do also in our office. If the duct is lined, oversize your duct to the size of your lining on both sides. Or other companies&nbsp;</P> <P>&nbsp; &nbsp; just draws lines without lining and then just add the "SL" suffix after the duct size.</P> <P>&nbsp;</P> <P>2. Yes, revit will calculate the static pressure based on free area.</P> <P>&nbsp;</P> <P>3. Sorry, can't comment on MEP since I'm not using it. Explore lisp, create a command that will tag the duct for you based on free area.</P> Fri, 05 Jun 2015 13:49:01 GMT jdiala 2015-06-05T13:49:01Z