Karl Hockless
There is a very good chance that the adhesive that was used to stick the tiles will be partially left on your ceiling. You should therefore be prepared to have a re-skim done. And it may even be necessary to have the ceiling over boarded prior to skimming depending on what damage is caused when the tiles are removed. Either way I would urge you to have the tiles removed as they give off toxic gas in the event of a fire. Don't be tempted to just overboard them.