Building code for kitchen exhaust venting

nheroldJanuary 28, 2007

I did a search online and on the forums but I haven't found an answer yet, so I appologize if this questions has already been asked.

DH is installing the wall-mounted chimney hood above our stove. We are trying to vent out the wall, not the roof (it's a new metal roof and we don't want to create a new hole). When we position the hood as low as is recommended the venting will come out of the wall right below where the eaves meet the roof.

Does anyone know the building code for how close to the eaves/roofline this type of venting can be placed?

If it makes any difference the venting is 6".

Thanks in advance for any insight you can shed.

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troubleseekeral

There is no code restriction on this type of ventilation to my knowledge. If it was a vent stack from a gas fired appliance, like a furnace or water heater, there are restrictions as to proximity to windown and doors, for obvious safety reasons.

    Bookmark   January 28, 2007 at 5:14PM
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mimsic

building codes vary from state to state and sometimes differ between municipalities. You need to contact either your city or state fire marshals office or buildings department for codes where you live.

    Bookmark   February 1, 2007 at 8:47PM
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mightyanvil

Since the exhaust air is not hot the only consideration is the possibility of staining the siding and/or the trim. A cowling and backdraft damper on the outside of the house should help. If the exhaust hood is a typical low-fan speed type and not placed too close to the stove top, I doubt there will be a problem (in fact they often move less air than cracking a window). The larger pseudo-commercail hoods with higher fan speeds usually come with adequate grease filters.

    Bookmark   February 2, 2007 at 8:56AM
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nherold

Thank you all for your comments and suggestions.

We contacted a contractor friend of ours and he told us that there are no restrictions in our area.

I'm not sure if the one we got is a pseudo-commercial (it moves 400cfm of air), but my DH is going to be building a vent cover out of our metal siding that directs the air downward, away from the eaves because we couldn't find a suitable one at one of the big box stores.

    Bookmark   February 2, 2007 at 11:23AM
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mightyanvil

Here is what should come with the hood kit.

    Bookmark   February 2, 2007 at 12:22PM
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nherold

Unfortunately it didn't.

That's what we are going to have to make.

    Bookmark   February 2, 2007 at 1:36PM
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mightyanvil

I have never been able to find any requirement for exhausting of a residential range. A residential range is defined in my jurisdiction as a range in a residence intended for residential use no matter how large it is. I have owned two true commercial ranges and have designed the hoods for them in restaurants and in private residences. The salesmen tell me the larger ranges must have a professional quality hood by law but when I ask for the code reference they change the subject. The botom line is how much air do you wnat to move out of your kitchen when you are cooking keeping in mind that you must allow the same amount of air to enter the house somewhere else. the large hoods almost always have a multi-speed fan. Most people run them at the lower speeds because you can't hear anything when the higher fan speed is on. Therefore, they do little more than a regular exhaust hood. If you burn something, opening a couple of doors and/or windows will bring in more air than any size fan. The best feature of the large hoods is the hidden lights and the warming racks with heat lamps.

    Bookmark   February 5, 2007 at 11:51PM
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scoobydoowts

I have a house in Alabama, the house was expanded for a carport and part of the original roof is now inside the attic. The kitchen vent is now venting in the attic. Is there a code that the kitchen exhaust MUST vent out the roof or is this acceptable? The whole roof has a ridge vent and attic fans keeping the attic vented. The stove is electric.

    Bookmark   May 13, 2010 at 8:21PM
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hockeychik

Scooby
Found this on the This Old House discussions site:
What's the problem with the hood vent venting into the attic (aside from stored stuff potentially taking on the smell of bacon)?

* coating the attic with grease residue - fire hazard as well as will attract pests
* dust and dirt from the attic coming back through the vent into the kitchen
* increased potential for house fire - both the creation of a combustible environment as well as stove top fire quickly and easily spread to attic.
* excess moisture not being vented to atmosphere (outside ) can cause mold and other issues (this is a regular question when venting bathrooms )
* in the case of a gas cook top with poor ignition or leak, raw gas will vet to attic - another possible fire hazard

How many of these things will happen in real world situations, it's hard to say, but venting the cook top vent into the attic is not a good thing. Vent it to atmosphere for safety and piece of mind.

    Bookmark   July 21, 2010 at 9:58PM
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macv

The 2003 International Residential Code requires that a range hood discharge outdoors through a single-wall duct with a back draft damper and that "ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building". The one exception is when the hood is "ductless" and designed to recirculate air directly back into the kitchen.

    Bookmark   July 22, 2010 at 6:18AM
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brickeyee

Sheet metal duct (not flex duct of any type) is also required.

    Bookmark   July 22, 2010 at 3:32PM
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macv

I don't allow any "flex duct" in a building I design.

    Bookmark   July 22, 2010 at 7:31PM
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brickeyee

"I don't allow any "flex duct" in a building I design."

It has its place in the last few inches of hooking registers to sheet metal for noise and vibration isolation.

I have seen entire houses with flex duct for every piece of duct.

It can work if the larger drops are accounted for in the duct design, but it does look bad.

It is at least more efficient than un-insulated sheet metal.

    Bookmark   July 23, 2010 at 8:43AM
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wtamasco_yahoo_com

I have a follow up question. If I don't want to make another hole on the roof can I take a " Y " metal channel in the attic and connect my stove top vent and my exhaust fan from my bathroom to the same exit roof vent

    Bookmark   January 18, 2011 at 8:47PM
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sierraeast

I asked a similar question at the hvac forum years ago although our application is venting out the wall. The answers all had included that it's not a good idea as odors from either can backdraft into the rooms. In the bath you'll smell kitchen cooking odors and vice versa. Being vented vertically up the roof with th "y" in the attic might be a different animal. You should run this by the hvac forum as well.

    Bookmark   January 19, 2011 at 11:42AM
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brickeyee

Thew dampers required for a Y to prevent back flow never seal perfectly, and often develop problems.

They also tend to have problems working from the start if the pressure in the two lines is not the same.

They are rarely anything more than a gravity flap sometimes supplemented with a weak spring.
If one side is higher [pressure than the pother the lower side may not even be able to open when the high side is being used.

    Bookmark   January 19, 2011 at 8:35PM
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davidro1

ditto brickeyee. both posts.

    Bookmark   January 24, 2011 at 9:48AM
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revoitalia_aol_com

i was just wondering if you can reduce the kitchen vent pipe from a 7'' to a 5''? , i really dont want a 7'' hole on the side of the house.

    Bookmark   February 6, 2011 at 1:12PM
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worthy

can I take a " Y " metal channel in the attic and connect my stove top vent and my exhaust fan from my bathroom to the same exit roof vent

Not in my jurisdiction--OBC 9.32.3.10. Ducts (6) )Ductwork for range hoods and range-top fans shall be of noncombustible, corrosion-resistant material and shall lead directly to the outdoors without connection to other exhaust fans or ducts.

    Bookmark   February 6, 2011 at 2:17PM
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juliekcmo

Steve,
A size reduction from 7 to 5 will restrict the volume of air that can flow through the venting considerably. Think of it like a water pipe.

    Bookmark   February 6, 2011 at 4:10PM
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jpmath_satx_rr_com

Why is it necessary to have a down draft on the stove top?
We had one when I was growing up and it never worked, I see no reason for one except to get rid of smell. Thank you

    Bookmark   March 3, 2011 at 9:55AM
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brickeyee

"I see no reason for one except to get rid of smell."

Ever seen the grease on the ceiling of a kitchen (and all over the cabinets) without any type of duct?

If you create smoke when cooking it has a fair amount of grease that settle all over the kitchen, and can even spread to nearby rooms.

    Bookmark   March 7, 2011 at 7:57PM
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