In Monopoly, what happens if we run out of houses and/or hotels?
Building shortages are part of the strategy of the game and it is intended that players might not be able to buy houses because of a lack of them in the bank. It is also intended that when a player has to sell a hotel they also have to sell all all houses as well if there are not enough in the bank.


  BUILDING SHORTAGES
  When the Bank has no houses to sell,
  players wishing to build must wait for some player to return or sell
  his/her houses to the Bank before building. If there are a limited
  number of houses and hotels available and two or more players wish
  to buy more than the Bank has, the houses or hotels must be sold at
  auction to the highest bidder.