Part of the new Destruction 2.0 process...you can easily take out houses. Some levels have MULTIPLE houses, others have hardly any...and not all shacks will be considered taking out a house. You know you have taken out a house that counts because it will make a creaking noises, sounds like metal bending...then after 2-3 seconds it will collapse.
Best missions for house destruction:
In the tank in Heavy Metal
With NoobTubes and C4 in Snowblind
On the way you will get the 1 house destroyed: