I live in a block of four flats with the communal area in the middle this is blocked by two entrances front door and back door. I sometimes wedge the rear door open to air the communal area . Is this illegal and against the law as a fire hazard to other residents in the block. ??

I would consider wedging fire doors open is illegal but if the rear door is a final exit door and not a fire door, then wedging it open would be acceptable, however it could be a security risk.