An easy way to know if the user have write access to a folder can be done this way:
public static bool HasWriteAccessToFolder(string folderPath)
// Attempt to get a list of security permissions from the folder.
// This will raise an exception if the path is read only or do not have access to view the permissions.
System.Security.AccessControl.DirectorySecurity ds = Directory.GetAccessControl(folderPath);
Happy coding! 🙂