Installing vented hood and exhaust, comments?

We had an over the range microwave with a recirculating exhaust fan. Didn't do anything for smoke, smelly air etc, so it's gone and I have a 900 cfm vent in the way. There is no existing exhaust vent, so I have to install one. I've installed a bathroom fan and exhaust, but this is a bit different.

Luckily the other side of the wall is the garage, so through the wall but unfortunately there's a stud in the way I'll need to deal with. Anyway, hood has 3 1/4 x 10 rectangle exhaust. I'll add a transition to 8" round, then a 90 degree elbow to go up through the drywall ceiling, through the OSB floor of the attic (hopefully missing any joists), a backdraft preventer then through the roof to a cap.

Anyone have a concise guide/things to-do/not-do link? One thing that puzzles me is I see no mention of support or joining the elbow to pipe to backdraft preventer to roof jack, other than foil tape. Is tape all all that's used? Is anything special needed for the pipe going through drywall or osb? This is a list of what I'm planning on buying for the install.

Any helpful comments or advice is welcome!

Edit to add - the backdraft preventer in my cart is the wrong size, I've corrected it to an 8". Also the quantities of things isn't accurate yet.

 

You scared me, man.

I thought a third gen guy was in here wanting to vent his hood and straight-pipe his exhaust

For the exhaust piping itself, it's not heavy and not really under stress so the foil tape is likely enough.

There's a ton of videos on Youtube detailing different kitchen exhaust vent installs.

There may be one that closely approximates what your situation is.

Here's one from This Old House

 

I'm not sure if you have done this yet but it'd think there may be a code for this because your going through two fire barriers. House to garage and garage to attic. You may need to use fire block rated expanding foam around the duct where it passes through the wall and ceiling. I know the ducts in my garage are also covered in sheetrock but can't remember if it was required or not.

 

Thanks for bringing that up. I haven't seen any mention of that when looking at range vent hood installation, surprisingly. I do know there are requirements for barriers between garages and living spaces. In those searches I didn't see mention of the fire foam, but that does make perfect sense. Whether it's mandated or not I will use it. When I return from driving my 1967 Camaro and park it in the garage.... wooo boy, it definitely off gases! Don't need that seeping into the house.

I've been looking at roof vent codes and found the 2/10 rule regarding combustion vents, but from what I can tell a range hood isn't in that classification. So I believe the one I'm going to use is fine (pic attached).

I've searched far and wide to see if there needs to be any kind of collar or some type of isolation between the pipe and the drywall/OSB but nothing comes up. I'd guess the exhaust isn't hot enough to necessitate it.

The hood arrived yesterday and after unpacking it I propped it up on packing foam and gave it a test run. It does move a lot of air!

 

Common range hood vent is 7" round. Look in the install instructions, typically there are steps to set the hood up to rear vent, top vent, rectangle or round.

Just installed a unit in our kitchen. Fortunately, most of the 7" round was existing. Although, it was only exhausted into the attic. Installed a roof hood, connected the 7" pipe, taped the joints, support the pipe with sling attached to the rafters. Changed the vent hood to round, cut holes in the cabinet, ran electric. Finally, the install.

Instead of dumping the kitchen exhaust in the garage, suggest to run straight to the roof with duct work and proper roof hood. Yeah, you'll need to cut a hole in the roof. Not a big deal, just need to set the shingles/roofing in layers working from the bottom up. A caulk gun with the roof flashing tube of black goo is handy to assure shingles and nails are sealed.


The roof vent I installed.

 

Through the roof has always been the plan (post #1 explains what I'm going to do - it's rather lengthy as I tend to ramble). I've got a 900 cfm hood, so while I could install a smaller diameter pipe, it would restrict it's effectiveness. 8 inch is what I'm going with. Got all parts on order...

 

I am saying....Don't go through the garage. Go straight up to the roof. A 7" pipe will be plenty to handle 900 cfm. Anytime you penetrate a garage wall, the risk of fumes and such entering the home is increased.

IIRC, the kitchen range hood I installed has a max air flow at 1200 cfm. My pipe run is roughly 15' with a pair of 45* ells, then the roof vent is equipped with a "weather flap". The purpose of the flap is to restrict cold air from entering the duct work. Kinda a air flow check valve.

Good luck with your install.


Well, it seems you are committed with the parts you have on order. Suggest simply go straight to the roof, avoid the detour through the garage.

 

From everything I've found you should be good to go unless you have overly strict local codes.

Fire block sealant is what I was thinking for around the duct. I looked at mine and the caulking style was used for thermostat wires that passed through the wall.




This brief article covers it.
https://structuretech.com/houses-dont-have-firewalls/