Kitchen venting

I have heard that it is recommended (or required) that if kitchen has gas stove, that the venting should be to exterior. I am running into a lot of such kitchens, new construction, where the only fan is the fan installed under overhead microwave that seems to only disburse the air inside, not vented to outside. What should I comment on such? Is it really a safety issue? Thanks

GS & TJ Services

Yes as an Indoor Air Quality inspector the levels of particles climb if not removed from the home and those particles can stay for hours mixing in with chemicals of off gassing. There is lots of info out about this kind of danger and not just CO is in question.
Personally if I had it my way I would not allow you to cook without a hood fan on just like you see in restaurants. An interlock that prevents cooking without would be a safety feature I would be all for.

It is not required to have the hood vent to the exterior. However, the appliance manufacturer will have installation recommendations. If they say it’s OK to have a recirculating fan, then it’s “OK”.
I am like Kevin, I prefer having the fan vent to the exterior.

Thanks William, do you think the manufactures care if you do or you don’t. NO!!! They want to sell sell sell and to put a hood in costs big bucks more depending on location requirements. I have always said this to my clients when they say **but but **the manufacture says it is OK or the AHJ says it is OK ect.

InterNACHI’s online course, “Inspecting the Attic, Insulation, Ventilation and Interior,” may be of help to ya.

Spot Ventilation in the Kitchen

75% are not vented to the outside.
Recommend ventilation if possible and if not I recommend a charcoal filter to cut down on the grease.

Make sure the fan is turned in the proper position also.

This is one of my pet peeves as I see newer construction that is ventless all the time.

You are getting no argument from me.
I am just saying that it is recommended, however, nowhere in the IRC is it required to have the fan vented to the exterior.

Here is another thread where we talked about it:

I have remodel my kitchen and my engineer suggest us to have exterior vent. I have done quite a lot survey and everyone says to have the fan vented to the exterior.
granite west palm beach

It’s not required but will be when states start to adopt the IECC. I often test gas burning ranges during my energy audits. When an over fires up it takes 5-10 min for it to get to steady state. During this time I have measured CO reading of up to 1500 ppm at the exhaust port for the oven. A CO meter on the counter was at 100 ppm. These levels are high for a short time but why would you want CO in your house at all. I suggest people get the fan to the exterior if possible.

It’s certainly a good idea, and exterior ventilation should be established whenever possible, however, as pointed out earlier, there is no requirement to do so in residential construction. Commercial kitchens are different, and do require exterior venting.

…and since you understand (I’m assuming) building science, you wouldn’t recommend a ‘restaurant’ style hood fan. Unless you want to create a massive backdraft with the flues on the furnace and water heater.


I see it all the time. Just did a brand new home with hood venting to inside. I just shake my head. I guess it’s how much money you want to spend. Personally vent to the outside is by far the best method. The only thing a cheap hood vent does is move the steam up and away from the stove for visibility. The same house they forgot to install a dryer vent in the laundry room.:mrgreen:

I recommend a vent to the outside for every I find even though it is not required.

Most clients had never even thought about it.

We are having our new house built. When talking about all the options, the builder’s sales rep asked us if we wanted electric or gas cooktop. We said gas. Then she asked if we wanted the hood to vent to the exterior or keep the standard recirculating one. We said vent to outside. So for an extra $180, we get to have the hood vent through the roof. We then proceeded to bathrooms, which have windows in them. She asked if we wanted bathroom exhaust vents. We said yes please. So for an extra $80 each, we get to have bath exhaust vents…
This is how this builder makes his money. He will build to the strict minimum (which is the code) and then will give you “options”. Moving an INT. door is an extra 50 bucks, just to move it.

Did you get a quote for a hip roof?

[quote=“jwicklander, post:11, topic:68997”]

…and since you understand (I’m assuming) building science, you wouldn’t recommend a ‘restaurant’ style hood fan. Unless you want to create a massive backdraft with the flues on the furnace and water heater.

Correct and an interlock with HRV.

Would you believe it if I said the hip roof was standard :shock: :mrgreen:

Did you make sure the bath vents are also vented to the exterior, not just dumped into the attic?

Sounds like a good deal

They haven’t started digging the foundation yet, so we have time to let them know :slight_smile:
The house will have spray foam insulation thought walls and attic, so they better vent it all to the exterior.