Has anyone been successful with a variance on the 10'-0" walk off-matt rule based on the limitations of a historic building? My building has an 8'-0" vestibule at the 2 main entrances. We have installed 6'-0" permanent walk off systems (metal grate in the floor) in the direction of egress. Do I need to add 4'-0" of roll-away matts on the other side of the vestibule to be compliant, or can we contend that the existing vestibule size only allowed for a 6'-0" walk-off system? The vestibule is a typical air lock type entry with two sets of doors (one at the exterior and on into the building). Any assistance would be greatly appreciated.