Sub: staircase differential pressure to between smoke zones
Case:-Medium rise (B+G+7) residential, non sprinkler building, 2 staircases, one staircase opening at ground floor to lobby & the other staircase directly opening towards outside(as per nfpa101 requirements). Since one staircase is direly opening directly to outside atmosphere, the differential pressure 25Pa (when 3 doors open including ground floor door) as per NFPA 92 is not achieved. Could you please confirm the differential pressure requirements for staircase opening directly to outside at ground level when 3 doors open including ground floor door. Or any alternate design requirements?