When having to go up and over existing ducts with new branch ductwork, what is the quickest way to get the elevations coordinated so the ducts do not conflict. For instance right now my ducts are center justified, when having to go up and over or beneath the existing duct with a new branch I have to scratch out on a piece of paper, a layout of the ductwork elevations. Taking into consideration the dimensions from center then adding insulation thickness etc.. Is there a tool that just gives you the Top of Duct elevation, Bottom of Duct elevation, etc. so the clearance values are more readily available?