Jamieson, Fausset and Brown on 2 Kings 9:13

13. they hasted, and took every man his garment--the upper cloak which they spread on the ground, as a token of their homage to their distinguished commander (Mt 21:7).

top of the stairs--from the room where the prophet had privately anointed Jehu. That general returned to join his brother officers in the public apartment, who, immediately on learning his destined elevation, conducted him to the top of the stairs leading to the roof. This was the most conspicuous place of an Oriental structure that could be chosen, being at the very top of the gate building, and fully in view of the people and military in the open ground in front of the building [Kitto]. The popularity of Jehu with the army thus favored the designs of Providence in procuring his immediate and enthusiastic proclamation as king, and the top of the stairs was taken as a most convenient substitute for a throne.