I am installing some velux windows in a new roof and want to fit the windows before the felt and batons so I can get a nice tight fit round the window with the felt. Normally the windows are fitted on tile batons running accros the top and bottom of the openings which are longer than the width, but I don't think this would work very well if I was felting afterwards. I think the window needs to be fixed at the same height as the top of the tile baton for the flashings to work properly, so does anyone know the best way to do this please?