Technical Booklet E Fire Safety·Page 77·2.91
Vision panels in doors
Glazed vision panels of at least 0.1 m² must be provided in doors that subdivide corridors or swing both ways, with specified zones of visibility in the lower and upper portions of the door.
A glazed vision panel, or panels of not less than 0.1 m2, should be provided in a door that subdivides a corridor, or where a door swings both ways. The vision panel or panels should include – (a) a lower zone of visibility not more than 500 mm to not less than 800 mm; and (b) an upper zone of visibility not more than 1150 mm to not less than 1500 mm, measured from the floor and located towards the leading edge of the door.
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