Part of our house is studwork upstairs (prolly because the downstairs used to be a 1-storey garage so inadequate foundations for building upstairs of brick). Anyway it was finished as tile-hung.
If you were replacing the windows in this situation (with new DG as it happens), would you expect to remove the tiles surrounding the window opening in order to seal the new window's edges to the plywood underneath the tiles, then replace the tiles and seal the window edges a second time, this time to the edges of the tiles?
Or would you consider that sealing just to the tiles would be enough? Seems to me both should be done, else wind gets under the tiles and can enter the stud cavity via the window edges.