Seasonal fluctuations in residential construction are quite large, and in business cycles from the early 1970s to the early 1990s, it was not uncommon for housing starts to drop by more than half. So it appears that this sector of the economy has evolved in such a way that it can expand and contract rapidly.
Moreover, in the current episode, the falloff in commercial construction has freed many resources that can readily be put to work building houses for now, then shifted back when business spending picks up.