E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
To cry from the house-top. To proclaim [it] from the house-top. To announce something in the most public manner possible. Jewish houses had flat roofs, which were paved. Here the ancient Jews used to assemble for gossip; here, too, not unfrequently, they slept; and here some of their festivals were held. From the house-tops the rising of the sun was proclaimed, and other public announcements were made.
That which ye have spoken [whispered] in the ear shall be proclaimed upon the housetops.Luke xii. 3.