Jamieson, Fausset and Brown on Isaiah 22:8

8. he discovered the covering--rather, "the veil of Judah shall be taken off" [Horsley]: figuratively for, exposing to shame as a captive (Is 47:3; Na 3:5). Sennacherib dismantled all "the defensed cities of Judah" (Is 36:1).

thou didst look--rather, "thou shalt look."

house of ... forest--The house of armory built of cedar from the forest of Lebanon by Solomon, on a slope of Zion called Ophel (1Ki 7:2; 10:17; Ne 3:19). Isaiah says (Is 22:8-13) his countrymen will look to their own strength to defend themselves, while others of them will drown their sorrows as to their country in feasting, but none will look to Jehovah.