tile In the Masons' language, to tile or cover the Temple is to protect it from 'rain-damage' caused by the intrusion of the uninitiated and of external influences. Thus one of the Outer Guards is the Tyler who only admits the candidate after he has answered questions suited to his grade. Unless it is "tiled" or covered, the Temple will let in the rain and hence, in French Masonry, the words 'It's raining' mean that there are uninitiated intruders in the Lodge meeting (BOUM).
Tiles symbolize the protection of a secret, and in their nocturnal aspect utter indifference to spiritual influences and the powers of self-development, a regression into what has been acquired and fixed. Thereupon the secret becomes corrupted and void of meaning.
Dictionary of SYMBOLS, ‘tile’