Range hood exhaust: proper duct material?

The Texas SOP says the following:

TAC 535.232(c) Range Hoods and Exhaust Systems:
The inspector shall report as deficient: improper duct material.

It also says the following:

TAC 535.231(h) Dryer Exhaust Systems
The inspector shall report as deficient: ducts that are not made of metal with a smooth interior finish.

In your opinion, what is “proper” duct material for range hood exhaust systems?

Before looking at the SOPs more closely, I would have told you that range hood exhaust ducts should be “metal with a smooth interior finish”. But now I’m second-guessing myself because TREC bothered to spell it out like that for dryer exhaust ducts, but wrote it differently for range hood exhaust ducts.

I am not from Texas, check local code. But I suspect smooth rigid metal pipe is fairly universal for range hoods.


Yea, thats how it always is in new construction around here. I think I found it. Thanks Brian!

504.3 Domestic Range

Ducts used for domestic kitchen range or cooktop ventilation shall be of metal and shall have smooth interior surfaces.

Exception: Ducts for domestic kitchen downdraft grill-range ventilation installed under a concrete slab floor shall be permitted to be of approved Schedule 40 PVC provided:

  1. The under-floor trench in which the duct is installed shall be completely backfilled with sand or gravel.
  2. Not more than 1 inch (25.4 mm) of 6 inch diameter (152 mm) PVC coupling shall be permitted to protrude above the concrete floor surface.
  3. PVC pipe joints shall be solvent cemented to provide an air and greasetight duct.
  4. The duct shall terminate above grade outside the building and shall be equipped with a backdraft damper.
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Texas has unique rules as compared to other states, but typically Code and the manufacturer’s installation instructions are go to sources for references to back up your observations.


yea, thanks. im mostly reviewing them to make sure I’m covering my ass from TREC complaints. You can look at all the violations online that they have issued to inspectors, and sometimes they can be strict!

One guy got fined $500 for neglecting to report missing exterior door weatherstripping! :roll_eyes:

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I think they are just purposely excluding the flexible foil and plastic dryer ducts because they are so common and readily available (and advertised as suitable) at the stores. Nobody uses those materials for range hoods so they didn’t feel the need to spell it out there. :man_shrugging:


I’ve seen flex used as a kitchen exhaust vent. Never say never :wink:. Florida Building Code (based on the IRC) calls for min 28 GA metal (going from memory, look it up yourself).


Never say never! :wink:
I was just reviewing a friends report last night and behold! A unicorn.



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Mine was a one of kind too. I’m not gonna take the time to locate the photo, I remember which neighborhood, but not the specific address. That is funny though! :grinning: :+1:


You would think it would be common sense that a range hood duct vent is metal considering cooking and grease and fire probabilities. I guess some people in this world need it spelled out. LOL


Oh, you’ve seen me cook then huh?



Yeah, a 4" foil slinky duct from a range is usually an indication that I’m in for a long day of report writing.


I can typically know that I’m in for a long day from the address. Sad but true.


Another thing to consider is was make-up air provided?

Just shooting from memory here but aren’t residential hoods limited to 600 CFM? That allows for enough make up air for a standard residential dwelling. Above that and you are into commercial kitchen hoods, etc. with a whole bunch of other requirements. This is along the same lines as why commercial cooking equipment isn’t allowed in residences - too many BTUs of fuel to the appliances. The guy that trained me as an HI 25 years ago is now a city inspector and does commercial… I still have beers with a few times a year and have learned a ton from him. Buying a few beers a year is the cheapest/best CE I’ve ever got… other than what I get here, of course :slight_smile:


This might come handy for some here on this subject, Matt.
CFM Requirements for Range Hoods: How Many CFM Do I Need?.

Room Size for Range Hoods

Next, consider the size of the room. The trend toward open kitchen layouts and higher ceilings influences the extent to which uncaptured particulates can travel. An effective range hood should be capable of exchanging the air in the kitchen every 4 minutes (15 times per hour) by volume to keep your indoor air clean.

For example, if you have an open-concept home, your kitchen may be located in a 20’ x 20’ room with 10’ ceilings.

20’ x 20’ x 10’ = 4,000 cubic feet

To figure the CFM needed for your size kitchen, divide the cubic feet by 4 (minutes)

4,000 ÷ 4 = 1,000 CFM range hood (or higher)


Here’s a reliable range duct in New Jersey :rofl:


I did an inspection that had a gas water heater vented with flexible plastic vent hose. Guess that fails! He didn’t get a license. Never say never.

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You’re right. I should have said “it is not common for people to use those materials for kitchen venting, unlike dryer venting where it is very common.”