Check welding of upvcdoors and Windows.  

Whether should see its weld place is even, whether have crack, the angular seam of inside and outside is cleared whether clean and beautiful, the diagonal dimension that measures model pvc door with box measure, its diagonal dimension difference should not be more than 3mm, diagonal difference is smaller show craft is finer, also benefit at installation.  

Check upvc doors and Windows of the hardware.  

The stand or fall of hardware quality also has certain influence to the life of door window, the hardware that uses looks should appear thick, and surface glossiness is close friends with, protective layer is dense, did not touch scratch phenomenon, more important a bit is open answer agile.