A pedestal for an access floor assembly, the pedestal comprising: a) a stand portion having i. a base plate for resting upon a sub-floor, and ii. a stem extending upwardly therefrom and having a square profile so as to define four side surfaces of the stem, b) a head portion having i. a platform, and ii. a threaded shaft extending downwardly therefrom, and c) a lockable nut having a hexagon shape and which has a thread adapted to screwably engage the threaded shaft, characterised in that the lockable nut has four detents to lock with the stem in order to prevent the rotation of the lockable nut along the threaded shaft when abutted against the stem, and wherein a first pair of the detents extend downwardly from a respective first pair of adjacent corners which define therebetween a first side surface of the lockable nut and a second pair of the detents extend downwardly from a respective second pair of adjacent corners which define therebetween a second side surface of the lockable nut which is opposite the first side surface of the lockable nut, and wherein the four detents individually lock with the four side surfaces of the stem by a first detent of the first pair of detents abutting against a first side surface of the stem, a second detent of the first pair of detents abutting against a second side surface of the stem which is adjacent the first side surface of the stem, a third detent of the second pair of detents abutting against a third side surface of the stem which is opposite the first side surface of the stem, and a fourth detent of the second pair of detents abutting against a fourth side surface of the stem which is opposite the second side surface of the stem. a) a stand portion having i. a base plate for resting upon a sub-floor, and ii. a stem extending upwardly therefrom and having a square profile so as to define four side surfaces of the stem, i. a base plate for resting upon a sub-floor, and ii. a stem extending upwardly therefrom and having a square profile so as to define four side surfaces of the stem, b) a head portion having i. a platform, and ii. a threaded shaft extending downwardly therefrom, and i. a platform, and ii. a threaded shaft extending downwardly therefrom, and c) a lockable nut having a hexagon shape and which has a thread adapted to screwably engage the threaded shaft, characterised in that the lockable nut has four detents to lock with the stem in order to prevent the rotation of the lockable nut along the threaded shaft when abutted against the stem, and wherein a first pair of the detents extend downwardly from a respective first pair of adjacent corners which define therebetween a first side surface of the lockable nut and a second pair of the detents extend downwardly from a respective second pair of adjacent corners which define therebetween a second side surface of the lockable nut which is opposite the first side surface of the lockable nut, and wherein the four detents individually lock with the four side surfaces of the stem by a first detent of the first pair of detents abutting against a first side surface of the stem, a second detent of the first pair of detents abutting against a second side surface of the stem which is adjacent the first side surface of the stem, a third detent of the second pair of detents abutting against a third side surface of the stem which is opposite the first side surface of the stem, and a fourth detent of the second pair of detents abutting against a fourth side surface of the stem which is opposite the second side surface of the stem.