Adjusting Floor Joist for HVAC

Trying to convert garage into family room. I want to run ductwork from basement to attached garage.

HVAC guy wants to put a vent under my front window. Problem is that the end of the garage (where the vent will go), is about 4' past the end of the basement. So if I took the ductwork out of the last basement bay, it would be about 4', and a few garage bays, away from the target vent location.

So I need the ductwork to come out of the basement wall, hang a left, go "through" a joist or two, and enter another bay. Then it can run down that bay and end in the vent.

So how should I adjust my floor framing to accomodate this duct? Is it possible to end my joist 6" before the wall, and "box it out". Will this have negative impacts on the strength of the floor?

Thanks,

Chris

wrldruler wrote: ...

What is going to support the joist if it ends short of the wall?

It would at the bare minimum have to have a multiple-thickness header on the adjacent joists for them to support it and, depending on the length, perhaps a center support. But, there could be a way possibly. It's possible if you use a substantial subfloor that the 6" span would be ok but again it depends on the length. Two short joists would be a span of

48" which would probably be ok w/ 3/4 T&G, three would be 64" -- there I start thinking "drum" even though it's narrow, that long a length w/ only side support is going to have some flex. More than that and I'd be looking for some way for sure to get some support across there.

Although on the joists -- are they essentially just resting on the floor since it's a garage? Or are they hung -- seems like maybe an earlier thread said somethng about raising floor to conventional 8-ft ceiling where is now 10-ft? If that were the case could not run duct underneath, perhaps?

So many questions, so little information... :)