public class LayoutFactory : ILayoutFactory  

//This example creates a new layout using a minimum set of parameters.

//Added references
using ArcGIS.Desktop.Layouts;                    
using ArcGIS.Desktop.Framework.Threading.Tasks; 
using ArcGIS.Desktop.Core;

public class CreateLayoutEx1
{
  async public static Task<Layout> CreateBasicLayout(double width, double height, LinearUnit units, string LayoutName)
  {
    Layout layout = null;
    await QueuedTask.Run(() =>
    {
      layout = LayoutFactory.Instance.CreateLayout(width, height, units);
      layout.SetName(LayoutName);
    });

    //Open the layout in a pane
    await ProApp.Panes.CreateLayoutPaneAsync(layout);

    return layout;
  }
}

//This example creates a new layout using a CIM page definion with rulers and guides included.

//Added references
using ArcGIS.Desktop.Layouts;                      
using ArcGIS.Desktop.Framework.Threading.Tasks;    
using ArcGIS.Desktop.Core;
using ArcGIS.Core.CIM;

public class CreateLayoutEx2
{
  async public static Task<Layout> CreateCIMLayout(double width, double height, LinearUnit units, string LayoutName)
  {
    Layout CIMlayout = null;
    await QueuedTask.Run(() =>
    {
      //Set up a page
      CIMPage newPage = new CIMPage();

      //required
      newPage.Width = width;
      newPage.Height = height;
      newPage.Units = units;

      //optional rulers
      newPage.ShowRulers = true;
      newPage.SmallestRulerDivision = 5;

      //optional guides
      newPage.ShowGuides = true;
      CIMGuide guide1 = new CIMGuide();
      guide1.Position = 25;
      guide1.Orientation = Orientation.Vertical;
      CIMGuide guide2 = new CIMGuide();
      guide2.Position = 185;
      guide2.Orientation = Orientation.Vertical;
      CIMGuide guide3 = new CIMGuide();
      guide3.Position = 25;
      guide3.Orientation = Orientation.Horizontal;
      CIMGuide guide4 = new CIMGuide();
      guide4.Position = 272;
      guide4.Orientation = Orientation.Horizontal;

      List<CIMGuide> guideList = new List<CIMGuide>();
      guideList.Add(guide1);
      guideList.Add(guide2);
      guideList.Add(guide3);
      guideList.Add(guide4);
      newPage.Guides = guideList.ToArray();

      Layout layout = LayoutFactory.Instance.CreateLayout(newPage);

      layout.SetName(LayoutName);
    });

    //Open the layout in a pane
    await ProApp.Panes.CreateLayoutPaneAsync(CIMlayout);
    return CIMlayout;
  }
}