Curtain Panels in Tally

Good morning,

I am trying to conduct a study comparing exterior envelope assemblies and façade design options. However, I have run into an issue with how we typically model our curtain panels and how Tally appears to assigns materials.

For our high rise buildings we typically model curtain panels to include glass, mullions, piers, and opaque spandrels/slab covers instead of stick-built curtain walls (the sort of “default” Revit method). This helps us ensure consistency around large floor plates and up the towers. Because all these subelements are included in one curtain panel Tally seems to be having difficulty appropriately calculating the area of each. For example, the amount of glass is being calculated as Total Panel Area x Component weight per area (29.85m2 x 21.4kg/m2 = 638.8kg) which means mullions, precast+brick, and piers are not being subtracted out.

This leads me to a couple questions: 1) Am I misunderstanding the data for examples like above? 2) If not, is there a workflow you would suggest to get Tally to accurately see each subelement of our curtain panels?

To put it another way, Tally seems to work by layering materials over the entire surface of an element (ie metal panel in front of insulation in front of membrane). Is it possible to tell Tally to put materials next to each other (ie window next to mullion next to metal panel) within one element?

Any guidance would be greatly appreciated!


Hi Stefan,

You’re not wrong, Tally has a hard time with complex families, especially curtain panel families containing multiple materials. I can’t say exactly how Tally calculates these things, but my guess after looking at a lot of similar takes offs is that the number reported from Revit to Tally is only the underlying data that Revit uses to place the family - length, perimeter, and area. What I’ve seen is that often times, if multiple materials are applied to a curtain wall panel family, each of those materials is seen as the whole curtain wall panel, and applied to the full area. What’s actually going on under the hood, though, who knows.

The way we’ve worked around this is that when we have a project that has complex panels is to do manual take offs. We then create a similar volume of material (or length/area, depending on what Tally needs) to serve as a stand in for the curtain wall in Tally. The stand in is modeled using a wall, with the thickness and size being consistent with the overall volume we’re trying to achieve. We’ve also skipped the manual take offs by asking the curtain wall manufacturer and/or structural engineer for material weights.

Hope that helps