Microwave vent

**Sam Morris** · 09-09-2020, 03:42 PM

Inspecting a house today that had the microwave vent terminate into the attached garage, near seen this before. I know its wrong x2, 1. firewall has been compromised 2. should be vented to the outside.
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**Jerry Peck** · 09-09-2020, 05:58 PM

Originally Posted by Sam Morris

1. firewall has been compromised

Note: that is a separation wall, not a firewall. Referring to it as a firewall is poor practice as a "firewall" is a very specific type of wall, and offers much more protection than a dwelling/garage separation wall ... least an inspector get hung out to dry for implying that wall is capable of something it is not ... that could happen.

But would likely only happen if there was a fire and that wall came into play.

Otherwise, yes, that installation of venting into the garage is wrong and not code compliant ... not even common sense compliant.

**david shapiro** · 09-13-2020, 07:23 PM

Originally Posted by Jerry Peck

. not even common sense compliant.

Can't you see pulling into the garage, opening the car door, and saying to yourself, "Ah, lasagna tonight!"

**Hilario** · 11-19-2020, 02:37 AM

I had that problem too. I hope by reading this forum, my problem will be solved.

**ROBERT YOUNG** · 11-23-2020, 05:51 AM

Can I see the microwave over please. Over 2,500 homes inspected and I have never come across a microwave oven that required venting.
Thank you.
Robert

**Gunnar Alquist** · 11-23-2020, 10:12 AM

Originally Posted by ROBERT YOUNG

Can I see the microwave over please. Over 2,500 homes inspected and I have never come across a microwave oven that required venting.
Thank you.
Robert

Robert,

Really? We have a lot of them installed above ranges and cooktops over here on the left coast. Some will recirculate back into the interior of the home and others will be ducted out to the exterior. I don't understand why all range hoods are not required to be ducted to the exterior.

**ROBERT YOUNG** · 11-23-2020, 11:14 AM

Originally Posted by Gunnar Alquist

Robert,
We have a lot of them installed above ranges and cooktops over here on the left coast. Some will recirculate back into the interior of the home and others will be ducted out to the exterior. I don't understand why all range hoods are not required to be ducted to the exterior.

Morning, Gunner.
Hope this post find you and all the Inspection News members, Jerry, David, Sam, etc...well considering the ongoing pandemic.
Keep safe gentlemen please.

Gunner. This would be covered under kitchen ventilation if I am not mistaken. The Microwave vent as posted by the OP thwarted my effort to make sense of the the treads topic.

'The depth of the hood should be a minimum of 24? inches in height from the range and should not exceed 36? inches. Higher hood top vents can/may improve capture efficiency but the fan should match the cook tops needs.
Hood tops are typically/normally/usually installed a minimum of, 6'6? - six inches @ six feet and a maximum of 7'0? seven feet above the finished flooring in accordance with code requirements to allow sufficient headroom for personnel.'

**Dom D'Agostino** · 11-23-2020, 01:18 PM

The Microwave vent as posted by the OP thwarted my effort to make sense of the the treads topic.

While I'm not entirely sure what that means, almost every single OTR microwave in the past 30+ years has the capability to vent "somewhere".

**ROBERT YOUNG** · 11-23-2020, 03:58 PM

Originally Posted by Dom D'Agostino

While I'm not entirely sure what that means, almost every single OTR microwave in the past 30+ years has the capability to vent "somewhere".

Dom, I have a 'microwave oven' that sits on the countertop above the drawers and a hood top to vent for the range.

What the OP referred to, if I am not mistaken, was venting the range through the microwave in place of a hood top. Maybe 20% of the homes I inspect use OTR microwave oven venting feature. As explained. I was confused my the topic, Microwave vent.
Hope that helps.

**Jerry Peck** · 11-23-2020, 06:25 PM

Originally Posted by ROBERT YOUNG

'The depth of the hood should be a minimum of 24? inches in height from the range ...

Depends on the manufacturer's installation instructions, many end up much less and are installed in accordance with the listing information.

... and should not exceed 36? inches.

While I haven't seen that, I suppose that could be a reasonable presumption to make, although a lot of old houses which has exhaust fans over the stove had the exhaust fans in the ceiling and were still effective as to drawing the cooking moisture out. Those installed in the ceiling were too high to affect grease laden air, which is the requirement for restaurants, but not for houses.

Higher hood top vents can/may improve capture efficiency but the fan should match the cook tops needs.

Kitchen exhaust fans in houses are there for moisture as well as grease (they do typically have grease filters which need regular cleaning, however, heating/boiling water for and during cooking creates a lot of moisture which is good to be exhausted outdoors.

The IRC requirement is: Table M1505.4.4 - Kitchens - 100 cfm intermittent or 25 cfm continuous

Hood tops are typically/normally/usually installed a minimum of, 6'6? - six inches @ six feet and a maximum of 7'0? seven feet above the finished flooring in accordance with code requirements to allow sufficient headroom for personnel.'

Most kitchen countertops are 36" (give or take) above the floor, and combustible material above the cooking surface needs 30" clearance above, which makes for 5'6". Many hoods are not much more than 6" or so high, putting the bottom of the hood at 5 feet above the floor.

Specialized (custom homes) hoods are a different animal and are installed in accordance with the manufacturer's installation instructions, and some of those are around your measurements of 6'7 ft in height above the floor, but many are only about 5-6 ft.