[If] one gives craftsmen [something] to improve, and they spoil [it], they are obligated to pay. [If] one gives a carpenter a chest, a box, or a closet to repair, and he spoils [it], he is obligated to pay.  [If] a builder undertakes to demolish a wall, and he breaks the stones or causes damage, he is obligated to pay. [If] he was demolishing from one side and it fell from another side, he is exempt; but if it was because of the blow, he is liable.