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Clothes Dryer Exhaust

M

Mech

REGISTERED
Joined
Oct 30, 2009
Messages
1,054
Location
Eastern PA
2009 IBC & IMC

3 story R-2 Apartment building

Is there any way to penetrate the ceiling membrane of the 1 hour floor/ceiling assembly with a domestic clothes dryer duct? IMC prohibits fire dampers, combination fire / smoke dampers and any similar devices that will obstruct the exhaust flow. Can I use a damper where the movable blades / pieces are retracted out of the airstream? Air flow should be unobstructed, but there is always the chance that lint will collect in the sliders.

Thanks
 
Mech said:
2009 IBC & IMC3 story R-2 Apartment building

Is there any way to penetrate the ceiling membrane of the 1 hour floor/ceiling assembly with a domestic clothes dryer duct? IMC prohibits fire dampers, combination fire / smoke dampers and any similar devices that will obstruct the exhaust flow. Can I use a damper where the movable blades / pieces are retracted out of the airstream? Air flow should be unobstructed, but there is always the chance that lint will collect in the sliders.

Thanks
Click to expand...
A little more detail would help. Vertical, and horizontal distance, residential or commercial dryer.
 
Can they put it in the vertical wall or in the assembly itself, without the penetration ??

What section says you cannot penetrate the ceiling??

Lights, bathroom vents , hvac other stuff that penetrates the ceiling
 
For whatever reason not all AHJ will allow listed duct wraps but it usually works well; use approved hangers to avoid damaged to the wrap. The problem with a chase is it interferes with HVAC ducts, sprinklers and joist penetrations.

Francis
 
If the duct is running horizontally above the membrane, it can turn down through the top plate of a wall and come out of the side of the wall, assuming its not a rated wall. See the exception to 607.6.1 of the IMC. Fire/radiation dampers are specifically prohibited in dryer ducts. All HVAC penetrations of a rated ceiling membrane require radiation dampers, including bath fans. Because dryers can't have dampers, they can't penetrate directly through the lid into the space. They have to come down in a wall and turn out of the wall. Bath fans can be put in the same way, mounted in the wall to save the cost of a radiaiton damper in the ceiling.

Any electrical boxes in the ceiling would also need to be listed for a rated assembly.
 
Even more specifically, look at IMC 607.6.2 Membrane penetrations. This gives 3 choices; 1- shaft, 2- ceiling radiation damper, or 3- ceiling radiation damper. 607.6.2.1, number 2, provides relief for the radiation damper provided the through penetration firestop system used in IBC 713.4.1.2 can be complied with. For me, T ratings are still in question ...

Francis, there are no "listed duct wraps" for this installation. There are no ventilation duct wraps listed for use in lieu of shaft construction. The PDF that cda provided earlier appears to indicate that there is, but this is not so. If a duct wrap was tested to ISO 6944 (which you will find on most ventilation duct wrap systems and the newest version of a clother dryer wrap system), it was tested to be used in lieu of a fire damper, not shaft construction.

This should stir things up :)
 
rgrace said:
Even more specifically, look at IMC 607.6.2 Membrane penetrations. This gives 3 choices; 1- shaft, 2- ceiling radiation damper, or 3- ceiling radiation damper. 607.6.2.1, number 2, provides relief for the radiation damper provided the through penetration firestop system used in IBC 713.4.1.2 can be complied with. For me, T ratings are still in question ...Francis, there are no "listed duct wraps" for this installation. There are no ventilation duct wraps listed for use in lieu of shaft construction. The PDF that cda provided earlier appears to indicate that there is, but this is not so. If a duct wrap was tested to ISO 6944 (which you will find on most ventilation duct wrap systems and the newest version of a clother dryer wrap system), it was tested to be used in lieu of a fire damper, not shaft construction.

This should stir things up :)
Click to expand...
Specifies a method of test and criteria for vertical and horizontal ducts under standardized fire conditions. The general purpose is to measure the ability to resist the spread of fire from one fire compartment to another without the aid of fire dampers. Is applicable to vertical and horizontal ducts with or without branches, taking into account joints, air supply and exhaust openings and suspension devices etc.
 
Gregg Harris said:
Specifies a method of test and criteria for vertical and horizontal ducts under standardized fire conditions. The general purpose is to measure the ability to resist the spread of fire from one fire compartment to another without the aid of fire dampers. Is applicable to vertical and horizontal ducts with or without branches, taking into account joints, air supply and exhaust openings and suspension devices etc.
Click to expand...
Exactly :)
 
716.6.1 Through penetrations.

In occupancies other than Groups I-2 and I-3, a duct constructed of approved materials in accordance with the International Mechanical Code that penetrates a fire-resistance-rated floor/ceiling assembly that connects not more than two stories is permitted without shaft enclosure protection, provided a listed fire damper is installed at the floor line or the duct is protected in accordance with Section 713.4. For air transfer openings, see Exception 7 to Section 708.2.

Exception: A duct is permitted to penetrate three floors or less without a fire damper at each floor, provided such duct meets all of the following requirements: You have to meet all 5 requirements in order to use this exception. Now with a dryer duct there is no grille opening so you would only need to meet requirements 1 through 4 correct?



1. The duct shall be contained and located within the cavity of a wall and shall be constructed of steel having a minimum wall thickness of 0.187 inches (0.4712 mm) (No. 26 gage).

2. The duct shall open into only one dwelling or sleeping unit and the duct system shall be continuous from the unit to the exterior of the building.

3. The duct shall not exceed 4-inch (102 mm) nominal diameter and the total area of such ducts shall not exceed 100 square inches (0.065 m2) in any 100 square feet (9.3 m2) of floor area.

4. The annular space around the duct is protected with materials that prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E 119 or UL 263 time-temperature conditions under a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.

5. Grille openings located in a ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly shall be protected with a listed ceiling radiation damper installed in accordance with Section 716.6.2.1.

716.6.2 Membrane penetrations.

Ducts and air transfer openings constructed of approved materials in accordance with the International Mechanical Code that penetrate the ceiling membrane of a fire-resistance-rated floor/ceiling or roof/ceiling assembly shall be protected with one of the following:

1. A shaft enclosure in accordance with Section 708.

2. A listed ceiling radiation damper installed at the ceiling line where a duct penetrates the ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly.

3. A listed ceiling radiation damper installed at the ceiling line where a diffuser with no duct attached penetrates the ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly.

Nothing here that helps



716.6.2.1 Ceiling radiation dampers.

Ceiling radiation dampers shall be tested as part of a fire-resistance-rated floor/ceiling or roof/ceiling assembly in accordance with ASTM E 119 or UL 263. Ceiling radiation dampers shall be installed in accordance with the details listed in the fire-resistance-rated assembly and the manufacturer's installation instructions and the listing. Ceiling radiation dampers are not required where either of the following applies:

1. Tests in accordance with ASTM E 119 or UL 263 have shown that ceiling radiation dampers are not necessary in order to maintain the fire-resistance rating of the assembly.

2. Where exhaust duct penetrations are protected in accordance with Section 713.4.1.2, are located within the cavity of a wall and do not pass through another dwelling unit or tenant space.

The OP can't use this section unless the dryer duct is located within the wall where it penetrates the horizontal assembly

It seems to me the code permits a horizontal penetration of a floor/ceiling assembly only if the duct is located within a wall. In my 15+ years as a sheetmetal worker I never penetrated a ceiling assembly with a dryer duct. We always went through the wall first.
 
MT nailed it. You can't come through the drywall ceiling membrane with a dryer vent. It has to come down inside of a wall assembly. Once you do that you can turn the dryer vent to come out of the wall.
 
Yea, and it cannot pass through another dwelling unit or tenant space. I think IMC 607.6.2.1, number 2 and IBC 706.6.2.1, number 2 (identical sections) nailed it.
 
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