Im about to rip off the old tiles and re-tile with some nice dark grey tiles(concrete ones)one thing im not sure about is how to fit the top row of tiles,added a photo showing a dry run i have done with battens at 100 centres,first row of tiles are the short ones,im just wondering how the top row will be fixed in the picture it is just hooked onto the tile below instead of a batten,is this the correct way to do it,with a bit of mortar underneath it? and do the light scuff marks what seem to be on most the tiles disapear after a bit of weathering?