The information in this article applies to:
When I use the Build Roof dialog to create an automatic roof, this message displays:
What is causing this problem?
When a roof is generated automatically, the program will try to build a roof plane bearing on top of each exterior wall in the plan, excluding Full Gable and High Shed/Gable walls. The program will also join each roof plane with adjacent roof planes, forming geometrically correct valleys, ridges, and hips. When conditions in the plan prevent the program from doing this in any part of the plan, it will present this warning message.
There are a wide variety of reasons why this warning message might display. However, the most common reason is that floor and ceiling heights in some part of the plan are such that the program cannot create roof planes over that area and have them join properly to the roof planes in the rest of the plan. This condition may also be accompanied by walls that have been incorrectly set as Full Gable, High Shed/Gable, Knee Walls, or Extend Slope Downward.
If you continue to have issues with your roof: