: You must build houses one by one across the entire group. For example, you cannot have three houses on one property and only one on another in the same group; they must stay within one house of each other at all times.
While the "at any time" rule is broad, there are practical limits and community etiquette to consider: when can i buy a house in monopoly
: There are only 32 houses in a standard set. If the Bank runs out, no more can be built until someone sells theirs or upgrades to a hotel. Timing Your Purchase : You must build houses one by one across the entire group