[A Man Sold a House, Then Took the Water Tanks, Doors, Windows, and Electrical Poles/Light Bulbs ]

The answer—and success is from Allah: What is to be followed is the customary practice (‘urf) recognized among the people in the town where the sale occurred. If the custom runs that these items are included in the sale, the seller is ordered to return them. If the custom runs that they are excluded, they are adjudged for the seller in case of dispute. If no custom has developed regarding any of this, then the ruling is for the seller with respect to what is not attached to and fixed in the fabric of the house. Thus say the scholars of the madhhab. They illustrated this with the stone mill: they deemed the lower stone to belong to the purchaser, because it is fixed and attached to the house, and the upper stone to belong to the seller, because it is not attached. As for the doors: if they are installed in the house with fixed installation such that they cannot be removed except by breaking and significant work, they are included in the sale; but if the doors are not fixed such that they can be removed without breaking or technical effort, they are not included in the sale. Likewise for the windows. Accordingly, rooftop water tanks are not included in the sale, because they are not fixed—this being in the absence of a custom either including or excluding them.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2