I had problems with getting firm details for window vertical and horizontal joints on our glazed gable. That has four vertical window-to-window joints, plus one horizontal joint (5 windows plus a glazed door, all joined together.
I don't know if there's a universal answer, as all I managed to glean in the end (after a lot of unsatisfactory correspondence with the window supplier) was that the vertical joints would use a slim aluminium cover piece, that would be integrated into one of the windows and then sealed during installation to its neighbour. The horizontal joint used a stacking cill, the details of which were never made clear prior to installation, best I got was a very scruffy faxed (!) drawing that turned out to be completely wrong anyway.
Yeah . I know that’s a ‘bad’ . But worked perfect before . Also the plug socket for reasons unknown upside down so I can’t plug the devolo direct into the socket .
i think Monday I’ll plug the devolo direct into a wall socket ( no extension lead ) then run a long rj45 to it .