The term is bētu epšu adi gušūrīšu. “A built house along with its beams.”
Legal conventions have a way of sticking around over time.
But building with mudbrick presents a problem: How do you add a roof?
(Source: news.bbc.co.uk/2/hi/middle_ea…)

Since trees large enough to provide beams of sufficient length are rare, roof beams became very valuable.
But demand for cedars led to deforestation in ancient times, and the cedars are considered a vulnerable species by the IUCN today.
(Source: jstor.org/stable/213080 )


So valuable that it was specified in contracts for the sale of real estate.
Sold on 16 Sivan (May/June) of 692 BC, to an Egyptian scribe named Ṣilli-Aššur.
Link: oracc.museum.upenn.edu/saao/P335268

Sold in Nineveh on 13 Ab (July/August) 641*
Link: oracc.museum.upenn.edu/saao/P335284
As Mallowan later admitted, he was completely within his legal rights to do so!