Abstract: A duct chase frame is substituted for a portion of the length of a conventional wooden or metal floor joist to facilitate running hot or cold air ductwork, plumbing and even electrical wiring. The frame includes a pair of elongated metal channels of uniform cross-sectional configuration with two metal spacers spanning and maintaining a joist accepting separation between those channels. One of the spacers is generally U-shaped for receiving and cradling a lower edge of one end of a floor joist, and the other spacer has an inverted U-shape for engaging an upper edge of the floor joist in a location intermediate the joist ends. The inverted U-shaped support is located near a first end of the pair of metal channels and the U-shaped support is located intermediate the metal channel ends. There may be a second inverted U-shaped support near a second end of the pair of metal channels for maintaining the separation between the pair of channels and for receiving and supporting a floor nailer.