I am adding a new bathroom where an old bedroom used to be on the first floor of a two-story house w/ attic. The bathroom does not share an exterior wall; it is separated from the exterior by a room. I am having difficulty finding a pathway to install the ducting from the fan through to the attic and out through the roof.

The fan I have selected is an in line fan (Nutone). I am curious to know if this can be vented in one of the two ways below.

1. Down through the wall cavity and floor, and out through the basement and basement wall (preferred and easiest path).

2. Horizontal through the wall cavity and out the side of the house (may need to build out around the ducting and sheetrock, etc... ).

Is it acceptable to vent downwards and horizontal rather than the traditional upwards or solely horizontal?

Vent through ceiling in bath then to roof peak if ridgevented or over to a eave vent grill. Cabo code says it is legal and you will not have to cut any holes to the outside.