Get Top Face Revit API

GetTopFace.cs

public static PlanarFace GetTopFace(Solid solid)
        {
            PlanarFace topFace = null;
            FaceArray faces = solid.Faces;
            foreach (Face f in faces)
            {              
                PlanarFace pf = f as PlanarFace;
                if (pf.FaceNormal.IsAlmostEqualTo(new XYZ(0, 0, 1)))
                {
                    topFace = pf;
                }
            }
            return topFace;
        }