Adjoining and communicating additions

What does Adjoining and communicating additions mean in American Law?

The definition of Adjoining and communicating additions in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

Especially in insurance contracts, the words “and communicating” are added to make clear that the “additions” covered must be in some physical contact with the structures to which they were added. Adjoining alone might not be legally sufficient to get that message across sufficiently to convince a judge.