# Dryer Exhaust duct - 1 hour wall penetration?



## Darren Emery (Dec 7, 2010)

In an apartment complex, 5B, 13R system - do you allow the dryer exhaust duct to penetrate the dwelling unit separation wall?  How about the floor ceiling assembly?  Or - must it be vented directly outside...

I know this is a fairly vague question - but I had to start somewhere.  The pertinent portions of the IBC and IMC are not clear cut on this issue, as we read it.


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## High Desert (Dec 7, 2010)

IMC Section 504.2 seems to allow it.

504.2 Exhaust penetrations. Where a clothes dryer exhaust

duct penetrates a wall or ceiling membrane, the annular space

shall be sealed with noncombustible material, approved fire

caulking or a noncombustible dryer exhaust duct wall receptacle.

*Ducts that exhaust clothes dryers shall not penetrate or be*

*located within any fireblocking, draftstopping or any wall,*

*floor/ceiling or other assembly required by the International*

*Building Code to be fire-resistance rated, unless such duct is*

*constructed of galvanized steel or aluminum of the thickness*

*specified in Section 603.4 and the fire-resistance rating is*

*maintained in accordance with the International Building*

*Code.* Fire dampers, combination fire/smoke dampers and any

similar devices that will obstruct the exhaust flow shall be prohibited

in clothes dryer exhaust ducts.


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## Darren Emery (Dec 7, 2010)

> and the fire-resistance rating ismaintained in accordance with the International Building
> 
> Code. Fire dampers, combination fire/smoke dampers and any
> 
> ...


Herein lies the challenge.  How do you maintain the rating, without a damper?


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## High Desert (Dec 7, 2010)

Through pentration firestop.


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## Francis Vineyard (Dec 7, 2010)

Had a 13R 5B apartment where they penetrated the rated dryer duct shaft a number of times with HVAC and bath vents with dampers, we permitted them to wrap the dryer duct with 3M Fire Rated Duct Wrap 615+.

Not everyone will approve.


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## Builder Bob (Dec 8, 2010)

100 inch rule for fire partitions..... seperations of dwelling units is by fire partitions not fire barriers..... Once the dryer duct or bathrom exhaust fans enters the wall face, it is allowed to turn 90 degrees and travel thru the stud cavity void to the exterior without dampers as long as the duct work is metal and continious from the inside to the point of termination ----- dryers are still sllowed to used the flexiable duct within the dwelling unit to the point of connection of the dryer duct where it penetrated the wall membrane.


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