@Infiltrated_ad8271 Gaza has a huge housing shortage as they lose more and more of their land and houses to "settlers" each year. They also have a lot of diffuculty getting building materials because of the blockades.
If you read this article about housing it talks about a guy building his house on the second story of a family member's house.
And the photos are basically showing us low rise apartment blocks. So by 'house' I think it means a small apartment block.
IDF bombed 4 of them too so maybe some of the extended family were in those.