Abstract: A removable deck for an interstitial space between stories of a building has joist saddles adapted to be permanently secured to building truss members in the interstitial space, each saddle having a socket into which the end of a joist may be dropped. The joists are channel type members of a length equal to the space between trusses. Each joist has an upturned flange at its top and the deck members, of a chosen length to extend across selected number of joists, have slots across their bottoms for close engagement with the upturned flange of the joist. The joists have a strip of rubber-like material along their upper surfaces and the upturned flange has dimple-like projections spaced therealong for holding sidewise movement of the deck members to a minimum. Each deck member is of inverted channel shape, the upper surface of which is longitudinally slitted to provide good air circulation.