Offset venting for replacement kitchen fan?

[MKepke]

Anyone run into the situation where they needed to offset in-the-wall ductwork?

My particular problem is that I need to exhaust a kitchen range hood down a stud cavity. The centerline of the stud cavity and the centerline of the hood don't line up.

I haven't bought the hood yet, but all the ones I'm seeing have the rear exhaust opening centered and fixed/immovable. f I install a common e.g. Broan range hood per the installation instructions, the ~10" rear vent opening on the hood will have 2-3" of the rear vent blocked by a stud(s) and the damper will be blocked closed.

Seems like my options are to find some make/model of range hood that allows offset rear-venting, or MacGyver cutting sheet metal and adding a plate to the range hood to shift the vent opening on the hood (not crazy about butchering a $300 hood leaving me with no warranty).

Other strategies?

-Mark

[EricU]

Maybe my reading comprehension wasn't good when reading your post, so sorry for that.

I would frame in a header and a box in the studs so the first distance from the vent could go diagonally. Fixing the wall after would be the biggest amount of work probably. 

I really want to get an induction stove and a downdraft air hood.  Our house is plumbed for downdraft stoves.  I think I can do it without any structure, but we might lose some cabinet space.

[Snipe Hunter]

Curious.. why do you want to run the duct in the stud cavity as opposed to a bulkhead over the hood?

[MKepke]

Curious.. why do you want to run the duct in the stud cavity as opposed to a bulkhead over the hood?

Yes, great question. The designated space for the range is against what may be a load-bearing wall.

Venting out the roof or a sidewall would mean going through a second story and an attic. Lots o' damage.

I want to avoid adding a header to 'move the stud cavity over' because that would mean pulling down the upper cabinets, a lot more drywall damage and reframing a cornerpost of the house (?). The offending stud is part of a wall-intersection but also tied into a triple stud.



-Mark

[Snipe Hunter]

Worst case, you could open the wall, cut the stud and frame it out like you were framing a window opening with cripples, jacks and kings. Just a lot smaller. With a base plate supported by jack studs, you could just. You would still be able to frame it to < 16" oc.

Not sure what you are buying but you could also leave the stud where it is and fabricate two ducts on either side of the stud. I'm assuming this is going to poke out the wall and vent to the exterior behind the hood? You'd loose a little air volume.

Does the vent hood have any specifications for exhaust duct size? That would help.

[fredhargis]

Looks like the sheet metal hack may be your only option. Personally I never worry about the warranty on stuff like this so my approach would be to start planning to cut away and fabricate.

[Willyou]

I assume the ducting in the stud cavity will be something like 2 1/2 x 10 rectangular metal. Can you just install that ducting in the cavity you have and then notch a wedge shape in the offending stud and fabricate a trapizoidal transition piece for the back of the hood? As long as you are not cutting all the way through the stud, it seems you should be OK structurally.

[jteneyck]

I think Willyou is right.  If you make sure that inboard stud is securely fastened to the adjacent stud(s) above and below where you notch it, the load bearing will not be compromised.  

John

[Snipe Hunter]

Cool.. like said above.. I'd probably notch that stud. Maybe run a couple lag bolts into what's left above.

Wasn't quite clear if you are running duct in the cavity or planing to use the cavity for the duct.. I'd run duct. Don't think I'd want steam or anything else an exhaust fan might pick up running in there without a duct.

Here's your sheet-metal

[EricU]

The way I'm interpreting those studs, you may end up cutting into the perpendicular adjoining wall cavity.  Then it becomes a real mess. I think it makes sense to get a sheet metal mechanic to modify the hood.