Salem

When a houses, ovens, smelters or any structures that are destroy, they should leave a pile of debris that could be harvested for left over materials.
Its like harvesting a coal clump, but the amount/number of items you could get has a low chance and you only get limited harvest from it.
Of course items obtained from those debris will be one of the building materials that was use for it.

Big structures should also randomly collapse in one direction killing everyone in the area of effect when smashed.