# Air Duct Penetration



## Francis Vineyard (Sep 25, 2012)

Haven't seen this done before; bathroom flex air duct penetrates sole plate from basement below then up through the top plate. Cannot see how this can be fireblocked; can someone point me to the code language where it is prohibited or allowed?

Thanks,

Francis


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## ICE (Sep 25, 2012)

Fiberglass batt insulation.  Foam that's listed as fireblock.  The code doesn't specifically say yes or no.  The code does say that the integrity of fireblocking shall be maintained.


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## Gregg Harris (Sep 26, 2012)

Francis Vineyard said:
			
		

> Haven't seen this done before; bathroom flex air duct penetrates sole plate from basement below then up through the top plate. Cannot see how this can be fireblocked; can someone point me to the code language where it is prohibited or allowed?Thanks,
> 
> Francis


 Francis try IRC 1601.1.1 (7) 7.4. and 602.8


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## Keystone (Sep 26, 2012)

Francis,

See this previous discussion, similar but not the same situation - http://www.inspectpa.com/forum/showthread.php?7641-Flex-Duct


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## north star (Sep 26, 2012)

*+ = +*

Francis,

Are you asking how to seal the bottom & top plates from

the flex ducting penetrations, ..or are you asking if the

flex ducting itself is an approved material to be

penetrating these locations....Sealing around the flex

ducting won't seal the fire blocked locations if a fire

propagates in the wall cavity it is located in.

*= + =*


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## DWM (Sep 26, 2012)

i always thought had to be rigid thru the floor - like 2" +/- but i dont have a book with me


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## steveray (Sep 26, 2012)

Is it listed for the use?

M1601.2 Factory-made ducts.

Factory-made air ducts or duct material shall be approved for the use intended, and shall be installed in accordance with the manufacturer's installation instructions. Each portion of a factory-made air duct system shall bear a listing and label indicating compliance with UL 181 and UL 181A or UL 181B.


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## Francis Vineyard (Sep 26, 2012)

Keystone said:
			
		

> Francis,See this previous discussion, similar but not the same situation - http://www.inspectpa.com/forum/showthread.php?7641-Flex-Duct


Keystone that's it, thanks.

From the above thread:



			
				mtlogcabin said:
			
		

> That's good news. It will help the fire get from the basement to the attic quicker.Seriously a chase is good because you have delt with the horizontial to vertical opening at the floor levels. However any unprotected shaft will create a chimney effect.


Exactly the concern.  Been out doing inspection this week; might be able to go back and get pictures before the finish.

Francis


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## Gregg Harris (Sep 26, 2012)

Francis Vineyard said:
			
		

> Keystone that's it, thanks.  From the above thread:
> 
> Exactly the concern.  Been out doing inspection this week; might be able to go back and get pictures before the finish.
> 
> Francis


Does this also help

According to the Air Diffusion Council that governs the installation of flexible duct systems states "Factory made ducts may not be used for vertical risers in air duct systems serving more than two adjacent stories.


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## Francis Vineyard (Sep 26, 2012)

It penetrates two stories and an attic; nothing prohibits this in IRC.  No changes in 2012.

On to another confusion.

Thanks again.

Francis


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## Gregg Harris (Sep 26, 2012)

Francis Vineyard said:
			
		

> It penetrates two stories and an attic; nothing prohibits this in IRC.  No changes in 2012.On to another confusion.
> 
> Thanks again.
> 
> Francis


Francis, I still think M1601.2 would apply. The UL 181 listing and the installers guide stating "Can not be used for vertical risers serving more than two stories in height".


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## Sifu (Sep 29, 2012)

Just to be sure, it is an air duct and not an air connector, right?


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## ICE (Sep 29, 2012)

Sifu said:
			
		

> Just to be sure, it is an air duct and not an air connector, right?


What's an air connector?


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## Francis Vineyard (Sep 29, 2012)

Sifu said:
			
		

> Just to be sure, it is an air duct and not an air connector, right?


Yes



			
				ICE said:
			
		

> What's an air connector?


The only place I'm aware where "air connector" is mentioned in the IRC;

*M1601.4.1 Joints and seams.* Joints of _duct systems_ shall be made substantially airtight by means of tapes, mastics, liquid sealants, gasketing or other _approved_ closure systems. Closure systems used with rigid fibrous glass ducts shall comply with UL181A and shall be marked_181A-P for pressure-sensitive tape, 181A-M for mastic or 181 A-H for heat-sensitive tape. Closure systems used with flexible air ducts and __flexible air connectors__ shall comply with UL 181B and shall be _marked_181B-FX for pressure-sensitive tape or 181B-M for mastic. Duct connections to flanges of air distribution system equipment or sheet metal fittings shall be mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply with UL 181B and shall be _marked 181B-C. Crimp joints for round metal ducts shall have a contact lap of at least 11/2 inches (38 mm) and shall be mechanically fastened by means of at least three sheet-metal screws or rivets equally spaced around the joint. Closure systems used to seal metal ductwork shall be installed in accordance with the manufacturer's installation instructions. 

*What is the difference between Flexible Air Ducts and Flexible Air Connectors?*



UL (Underwriters Laboratories) in their *UL 181 Standard for Factory-Made Air Ducts and Air Connectors*, defines two categories of flexible "ducts" 

The UL Listed Flexible Air Duct must pass all of 15 tests in the UL 181 Standard. Air Ducts are labeled with a square or rectangular label showing their respective listing. There is no limitation on the length of runs when using UL Listed Air Ducts. 

The UL Listed Flexible Air Connector must pass only 12 of the 15 tests of the UL 181 tests, and is labeled with a round shaped label, which states "_for installation lengths not over 14 feet_". An installer may not increase the 14-foot limitation by using a splice between 14' sections of Air Connectors. This length limitation is set by the requirements in NFPA 90A & 90B Standards. 

http://www.flexibleduct.org/ADC_FAQs.asp

Francis


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## ICE (Sep 29, 2012)

Thanks Francis.  I guess I shouldn't be so lazy.  I don't have the mechanical portion of the IRC but the CMC mentions air connectors.

602.3 Factory-Made Air Ducts. Factory-made air ducts shall be approved for the use intended or shall conform to the

requirements of the referenced standard for air ducts in Chapter 17. Each portion of a factory-made air duct system

shall be identified by the manufacturer with a label or other suitable identification indicating compliance with the referenced

standard for air ducts in Chapter 17 and its class designation. These ducts shall be listed and shall be installed in accordance with the terms of their listing.

*Flexible air connectors are not permitted.*


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