True, installing a half-inch gypsum board is a safety requirement under stair enclosures to enhance fire protection and prevent the spread of fire and smoke.
The statement that an enclosed accessible space under stairs should be protected on the enclosed side with a half inch gypsum board is True.
This is a common fire safety requirement found in building codes to increase the fire-resistance rating of the stair enclosure and provide additional protection in case of a fire.
Installing half-inch gypsum board on the enclosed side of the stairway helps to prevent the spread of fire and smoke between levels of a building, allowing occupants more time to escape and fire services more time to respond.