Mostafa Tavengar
Hi Helen, This is a matter of either or, whatever your preference. If you choose to incorporate it and want a nice finish, put a couple of good sized dollops of silicone sealant every 40 cm or so on the wall where the mirror is going. Next, line the bottom edge of the mirror up with the tiles and gently push the mirror back until it is level and at a similar depth to the tiles. As soon as it is level, leave it alone for a day or two, then seal all around the edges with sealant. Job's a good 'un! Hope this helps :-) Best wishes Mostafa Bedford Building Maintenance