The PermissibleDuctThicknessPerSpec sheet in the HVAC.xls workbook defines the allowed thickness of various duct materials that you want in the Catalog.
This data must also be defined in the PermissibleDuctThickness sheet in the HVAC.xls workbook.
Specify the name of the HVAC specification.
Type the name of the material, such as steel - carbon.
Type a grade for the material.
Type a thickness value for the material in mm (millimeters) or in (inches).