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Range Hood Exhaust


Forum Coordinator
Oct 16, 2009
Somewhere Too Hot & Humid
OK, so we are all aware of this:

M1501.1 Outdoor discharge. The air removed by everymechanical exhaust system shall be discharged to the outdoors.

Air shall not be exhausted into an attic, soffit, ridge vent or

crawl space.

Exception: Whole-house ventilation-type attic fans that

discharge into the attic space of dwelling units having private

attics shall be permitted
Then there is this:

RANGE HOODSM1503.1 General. Range hoods shall discharge to the outdoors

through a single-wall duct. The duct serving the hood

shall have a smooth interior surface, shall be air tight and shall

be equipped with a backdraft damper. Ducts serving range

hoods shall not terminate in an attic or crawl space or areas

inside the building.

Exception: Where installed in accordance with the manufacturer’s

installation instructions, and where mechanical or

natural ventilation is otherwise provided, listed and labeled

ductless range hoods shall not be required to discharge to

the outdoors.
The last exception essentially cancels out the requirement because just about every single recirculating hood is listed and labeled. A kitchen with an operable window meets the ventilation exception.

I thought they were going to tighten this up when they added the 400cfm makeup air code.

Re: Range Hood Exhaust

I'm more familiar with the UMC, which doesn't even require a range hood for residential....
Re: Range Hood Exhaust

Jeff - It really only 'cancels out' the requirement IF you use a ductless hood. If you use a ducted hood, then the requirement is that it discharge to the outside air. We may be seeing more ductless these days, but some are still using ducted.

beach - Range hoods aren't required in IRC either, but if you do install one, it shall comply with...
Re: Range Hood Exhaust

Oregon amended the IRC to require all ranges to have hoods and be ducted to the outside. We don't have to deal with all of that anymore.
Re: Range Hood Exhaust

Yea; every now and then it appears that the code committees are actually doing some work. ;) :p
Re: Range Hood Exhaust

Not aware of the window exception in the kitchen , but have allowed a window in a bathroom in place of a fan, it's there in the code somewhere.

Will allow vented bath fans to discharge at a vented soffit or throught the roof.

Had a house where the bath fan vented to the soffit at the front porch, every time you would ring the door bell , I swear it smelled like gas! :shock: :eek:
Re: Range Hood Exhaust

Pcinspector1 said:
Will allow vented bath fans to discharge at a vented soffit or throught the roof.
At a vented soffit or through the soffit. The code doesn't allow to just dump the exhaust into the soffit. It must be to the outside.