G disabledBuildables

Usage
This variable can for example be set by a map. In the worldspawn, add the key "disabledbuildables" and set its value to a comma delimited list of buildings (e.g. "acid_tube,barricade,mgturret") that is to be unavailable in the builders' menus. Binds cannot override this.

With this in mind, see also G_disabledEquipment and G_disabledClasses.