# Grease Duct Enclosure Termination



## fatboy (Feb 14, 2013)

We have a new steak house going into an old building. The grease duct has been routed through the building, penetrates an exterior wall at the top of first floor, goes up the side of the building to the third floor where it the goes back onto the roof and exhausts. The contractor terminated the duct enclosure (wrap) where it exits the building at the first floor. At final my inspectors call the contractor on it, citing 2012 IMC 506.3.11.2, which states the enclosure must be continous to the outlet terminal. The engineer is claiming the outlet terminal is where the duct exits the building, not the exhaust outlet. I know they need to protect it as required by 506.2, and part of me has trouble with requiring the wrap on the exterior of the building, but I think the outlet terminal is the point of exhaust. Opinions?


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## cda (Feb 14, 2013)

Sorry hate to say, I have to agree with an engineer

Thank about even when it goes straight up and you have say three feet of duct  above the roof line, that three feet is not protected

Yes I have seen your set up before with no protection

Now do not know if you had a property line near, if that would change the answer


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## Codegeek (Feb 14, 2013)

Since the purpose of the grease duct enclosure is to protect other areas of the building from the spread of smoke and fire from the kitchen, I'd say once it penetrates the exterior wall, it's reached the outlet terminal.  If you believe the installation is not achieving providing for this protection, then I think you may have an argument.  Otherwise I think the engineer is correct.


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## north star (Feb 14, 2013)

*$ = = $*

What about Section 506.3.11. [ `12 IMC ]......*506.3.11 Grease duct enclosures.*

"A grease duct serving a Type I hood that penetrates a ceiling, wall, floor or any

concealed spaces shall be enclosed from the point of penetration to the outlet

terminal." ?



*= $ $ =*


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## fatboy (Feb 14, 2013)

That was the question.....what constitutes the "outlet terminal"?

I had pretty much worked myself into accepting the installation, as long as they protect it as 506.2 requires. Just wanted some reinforcement that I was looking at it as in under the intent of the code.


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## mtlogcabin (Feb 14, 2013)

Question

1 is the exterior of the building combustible and is there sufficient clearance from combustibles?

2 It gets pretty cold on Colorado will the duct maintain sufficient temps and keep excessive build up of grease on the inside?


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## fatboy (Feb 14, 2013)

Non-combustible construction, 3" separation. The temp question was raised with the engineer, he said at the velocity they are moving the air, it will only be in that part of the duct 4-5 seconds.


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## north star (Feb 14, 2013)

*= =*

fatboy,

Im my simple mind, an exhaust "outlet terminal" would be where the duct stops

[ i.e. - stops / ends ].

Also, I'm thinking along the lines of **mtlogcabin** as well, ...the congealing

of F.O.G. in that vertical duct.

*= =*


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## north star (Feb 14, 2013)

*# #*

So the question becomes, ...is the "wrap" required for thermal protection

of the duct system [ on the exterior, ...in colder climates ], as well as,

protection from combustible surfaces  ?

*# #*


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## cda (Feb 14, 2013)

Well you install a rated shaft or wrap

Are you trying to protect the building from the duck or the ducks from the building??

Come on get your ducks in a row


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## klarenbeek (Feb 15, 2013)

I agree with north star. Outlet TERMINAL would mean where the duct ends.  The reason for the code change was based on the listing of the grease duct wrap.  It was never actually listed to only wrap just portions of the duct for clearance reduction only.

Perhaps the contractor could avoid the problem by using the shaft enclosure in section 506.3.11.1.  I haven't seen it used in years, but it is an option.


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## cda (Feb 15, 2013)

So is the base of the exhaust fan the terminal?

And everything below that is duct work???

So on this one do you wrap it to the base of the fan??????

http://www.michiganexhaustcleaning.com/neglected_coney_island_exhaust_fan.jpg


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## north star (Feb 15, 2013)

*+ + +*





> "So is the base of the exhaust fan the terminal?"


Where the ductwork actually stops/end is the termination point [ i.e. - the terminal ].







> "So on this one do you wrap it to the base of the fan??????"


Section 506.3.11 [ from the `12 IMC ] requires that all duct work be enclosed, not necessarily"wrapped" per se', except, Section 506.3.11.4 does not require enclosure......From *Section*

*506.3.11.4 - Duct enclosure not required: "*A duct enclosure shall not be required for

a grease duct that penetrates only a nonfire-resistance-rated roof/ceiling assembly."

**cda**,

In your picture, that exhaust outlet does not appear to be 40 inches above the roof surface.

[ RE: *Section 506.3.13.1 Termination above the roof.* "Exhaust outlets that terminate above

the roof shall have the discharge opening located not less than 40 inches (1016 mm) above the roof

surface."......Am I just seeing it wrong?  



*+ + +*


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## cda (Feb 15, 2013)

north star said:
			
		

> *+ + +*
> 
> Where the ductwork actually stops/end is the termination point [ i.e. - the terminal ].
> 
> ...


S

I do not know, one of them Internet things

To me in that picture the duct ends at the bottom of the fan


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## fireguy (Feb 15, 2013)

While not part of the code, an exhaust system must be cleaned, to remove combustable grease.  If that duct is away from the building, how far would be comfortble leaning over the edge of the building.  Now think about doing that at 2:00 AM, ice on the roof.

Back to the code.  A fan is to be hinged so the fan and duct can be cleaned of the grease.  NFPA 96-2011-11.6.2 Hoods, grease removal devices, fans, ducts, and other appurtances shall be cleaed to remove combustable contaminants jprior to surfaces becoming heavily contaminiated with grease or oily sludge.  Defining depth of contaminants is  A.11.6.2, grease should be cleaned to 0.002 " depth.

 No way would I accept a job, knowing the duct and fan is not accessable.  And having to lean over the edge of the roof is not accessable.


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## cda (Feb 15, 2013)

Op

Appears to state that the exhaust fan winds up on the roof


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## Codegeek (Feb 18, 2013)

Fatboy, I would contact Sam Dardano since he's from your neck of the woods and very involved in the IMC.  See what he has to say about it.


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## fatboy (Feb 18, 2013)

Yeah I thought of that also, I will be seeing him Friday for our Chapter meeting, he is presenting.

I also have an interp request in with the ICC.

Thanks all........


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## cda (Feb 18, 2013)

so they wrap the outside duct work.

How long is that going to stand up to the weather??

and once again why is the wrap there in the first place?? what are you trying to protect


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## cda (Feb 18, 2013)

if you have a handbook it shows that the wrap or shaft ends at the roof line


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## fatboy (Feb 18, 2013)

yes it does, on both illustrations.................


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## cda (Feb 18, 2013)

View attachment 676


OpIs this kind of what they are proposing ???Sorry about the orientation And someone wants a shaft or wrap from where it comes out of the building all the way to the fan???
	

		
			
		

		
	

View attachment 676


/monthly_2013_02/image.jpg.191503633b33dbf339c808f39ac25c5e.jpg


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## fatboy (Feb 18, 2013)

Exactly.......and the someone was my inspectors, but then I had some heartburn with it. BTW, the building is masonry, and the duct has the required 3" separation. I'm still waiting on an interp from ICC.

BTW, seldom do I question my inspectors, but based on the responses here, it is not a clearly written section. Can someone say, code change?


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## cda (Feb 18, 2013)

fatboy said:
			
		

> Exactly.......and the someone was my inspectors, but then I had some heartburn with it. BTW, the building is masonry, and the duct has the required 3" separation. I'm still waiting on an interp from ICC.BTW, seldom do I question my inspectors, but based on the responses here, it is not a clearly written section. Can someone say, code change?


My boss questions my calls all the time.

Of course I give him good reason to


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## fatboy (Feb 21, 2013)

Well, the response from ICC backs my initial gut check;

RE:  Sections 102.9 and 506.3.11 of the 2009 International Mechanical Code

 This staff opinion is in response to your correspondence, dated February 14, 2013, regarding the above referenced code.

 Q.   Does Section 506.3.11 require grease duct enclosure protection of an  exterior grease duct that runs through the exterior wall to the outside  and up three stories along  an exterior wall to its termination point at the exhaust fan above a  roof?

 A.   The purpose of a grease duct enclosure is to protect the occupants and  building from a fire within a grease duct.  As most of the figures in  the 2009 IMC Commentary  illustrate, our opinion is that the grease duct enclosure requirement  intends to address grease duct enclosure protection for grease ducts  within the building, but assumes the termination point at the exhaust  fan discharge is near the penetration of the wall  or roof assembly.  The verbiage in the text is silent on the  requirement for a grease duct enclosure for an exterior grease duct that  runs through the exterior wall to the outside and up three stories  along an exterior wall to its termination point at an exhaust  fan above a roof.  In our opinion, an exterior grease duct enclosure is  not required since the duct is not connecting floors of a building and  is not located within the building.  Please note that a grease duct that  runs up the outside of a combustible exterior  wall must still maintain a clearance to combustibles of 18-inches.  The  code official needs to determine on a case-by-case basis, whether there  is a potential fire and life safety risk to the building and its  occupants.  The code official might need to consider,  but not be limited to, the grease ducts proximity to openings and exits  along with the type of exterior wall finish material.

 Code  opinions issued by ICC staff are based on ICC published codes and do  not include local, state or federal codes, policies or amendments. This  opinion is based on  the information which you have provided. We have made no independent  effort to verify the accuracy of this information nor have we conducted a  review beyond the scope of your question.  This opinion does not imply  approval of an equivalency, specific product,  specific design, or specific installation and cannot be published in  any form implying such approval by the International Code Council. As  this opinion is only advisory, the final decision is the responsibility  of the designated authority charged with the  administration and enforcement of this code.


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## cda (Feb 21, 2013)

fantastic>>>>


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## north star (Feb 21, 2013)

*+ + +*

fatboy,

Thanks for posting the ICC interpretation!.......That information helps

us all!    :agree

*+ + +*


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