After World War II, tens of millions of ethnic Germans from Central and Eastern Europe were forcibly expelled into Allied-occupied Germany and Austria. What happened to all the homes they left behind? That is, to whom was ownership transferred—were the expelees given the opportunity to sell their real estate on the private market, or were they obliged to transfer ownership to the newly installed or restored governments, or was the property simply abandoned with no legal formalities? If the properties were typically nationalized or abandoned, then how were homes reallocated? Did the governments systematically survey the evacuated properties and try to match them up with locally displaced citizens, or was the process more haphazard? Were there any less war-torn countries that ended up with a housing surplus?
It happened in different countries and it was different, of course.
In the Czech Republic there were four stages of gaining the former German estates. At start practically anyone could move in and claim a house or a farm, often throwing off or killing the previous owners. In more lucrative places that way was stopped by bureaucracy almost at once. On the contrary, many mountain villages were never populated and died off. All estates were counted, confiscated and sold off or given. As for real estates, they were given temporary. Later (from 46) they have got these estates as owners, not users. The speed of changes differed greatly - in some places they already got estates as owners, and in neighbouring places confiscation merely started.
Taking estates from somebody else was very pleasant experience and sometimes it was repeated on the same plot or farm or factory. The next owner had better connections and thrown off the previous one. The documents and law ceased to mean anything. Administrative or military resource or personal arms meant much more. Sometimes even the President couldn't help. People, who, got these estates, could not correctly use them. They only misused them or sold off. Mostly these estates were destroyed.
Of course, that socialistic behaviour helped greatly to the winning of Communists in the 1948 elections. The socialistic state, that appeared, at start used the German estate as a level for gaining influence. At the end, the estates were taken from them (not usual houses though) and joined in kolchoz or nationalized.
Here you can read the thorough analysis about processes in one former German region. (http://www.valka.cz/14363-Ekonomicke-a-socialni-dopady-odsunu-Nemcu-na-Jesenicku-v-letech-1945-1947)