There is provided a railing post adaptor for a roof support apparatus. The roof support apparatus comprises an elongate member having a plurality of longitudinal sides. The railing post adaptor comprises a roof support apparatus connector for securing the railing post adaptor to the roof support apparatus. The roof support apparatus connector comprises a first connection portion arranged to engage, in use, with a first set of the plurality of longitudinal sides, and a second connection portion, movably mounted to the first connection portion and arranged to engage, in use, with a second set of the plurality of longitudinal sides, the second set being different from the first set. The roof support apparatus connector further comprises a railing connection portion extending from the roof support apparatus connector for detachably securing a proximal end of a railing post to the roof support apparatus via the railing post adaptor. The first set and the second set each comprise at least two longitudinal sides. The first connection portion and the second connection portion are together configured to substantially prevent rotation of the railing post adapter about a longitudinal axis of the elongate member by engagement with the first set and second set of longitudinal sides.