1.   Flip the switch on the fan housing to reverse the direction of the fan blades so they draw air up.

2.   From the underside of the roof, select a spot near the fan housing for the exhaust pipe to poke through the roof.

3.   Hold the fan housing in place over the opening and have an assistant in the bathroom below attach the grille facing to the fan housing.

4.   Insulation resting against a hot fan housing is a fire hazard.

5.   It will be easier to attach the insulated ducting to the fan housing before it is mounted between the joists.

6.   Next, dismount the fan housing and try to separate it from the joists, using connectors like those used to mount an engine in an automobile.

7.   Push the ducting and the fan housing through the hole in the bathroom ceiling.

8.   Run a length of flexible exhaust hose from the outlet on the fan housing to the tailpiece of the vent.

9.   The insulation should not come over the fan housing or blades.

10.   This saw cut will serve as a guideline for tracing the outline of the fan housing.