Describes method for determining the fire resistance of door and shutter assemblies and openable windows designed for installation within openings incorporated in vertical separating elements, such as: a. hinged and pivoted doors; b. horizontally sliding and vertically sliding doors including articulated sliding doors and sectional doors; c. folding doors, sliding folding doors /shutters; d. tilting doors; e. rolling shutter doors; f. openable windows; g. operable fabric curtains.