The roofs cannot be joined because the roof being joined meets the target roof tangentially.

public static FailureDefinitionId RoofMeetsRoofTangentiallyError { get; }

Public Shared ReadOnly Property RoofMeetsRoofTangentiallyError As FailureDefinitionId
	Get

public:
static property FailureDefinitionId^ RoofMeetsRoofTangentiallyError {
	FailureDefinitionId^ get ();
}