I hope someone in the forum has had some experience with the following.
I was recently asked to generate a ductwork takeoff on a sub-consultants model just to double check their numbers. This task was first done in Revit 2014 via the ductwork schedule. The only things I included in the schedule were: Width, Height, Length, and Area. The total square footage calculated by Revit, excluding all accessories and fittings, was ~370K
After seeing what Revit had calculated, I wanted to check if I could replicate the same results in Navisworks. I created a custom Item Catalog under "Metals," and then generated it's associated Resource Catalog. I modified the Volume Resource Calculation (ModelWidght*ModelHeight) to get my area and then used the Selection Tree to add my ductwork to the Quantification Workbook. Once everything was complete, I exported the quantities to excel and check the total ductwork square footage. To my surprise the number was ~649K.
It's still unclear to me as to how the two numbers can be so different. I thought Navisworks simply reads whatever information is exported from Revit. However, this leads me to believe otherwise. One more piece of interesting information; the total Linear Feet Number is the same in both Revit and Navisworks: 37K
Any light anyone can shed on this is greatly appreciated.
Thank you,