In my alliance there are numbers of building that were started to be upgraded, because of lack of information to another level, and stopped at the middle of the tasks. All those materials are useless unles we finish building; but some construction like 'desk' in 'bar' cannot be finished if bar is bellow level of headquarters.
Therefore I'm suggesting to develop new building, a stockpile for materials - players could put their materials here instead of any other construction,. Leadership could decide were use materials stocked in stockpile. If there would be materials that are no longer useful for alliance, there should be option to upgrade them to another level or lowered building requirements to lower level.