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Multi family dryer venting

M

Michael Brown

SAWHORSE
Joined
Mar 27, 2017
Messages
37
Location
Covington, GA
Depending on the jurisdiction we work in we see different interpretations of the IBC concerning the penetration of the dryer pipes from the laundry area to the exterior wall. Some jurisdictions are requiring dryer wrap and others are not. 2015 IMC 607.1.2 states that the penetration must comply with 2015 IBC 714.4 which deals with horizontal assemblies not required to be in a shaft. 714.4 states that the assemblies must comply with 714.4.1.1 through 714.4.1.4.. 714.4.1.1 deals with through penetrations and 714.4.1.2 deals with membrane penetrations. Both have a similar exception 1 which seems to indicate that all that is required is that the annular space must be protected. I don't believe that the remaining two sections apply in our case. I believe the dryer wrap requirement is based on 714.4.1.1.2 which requires a through penetration fire-stop system but doesn't exception 1 apply to a dryer pipe and negate that requirement?
 
So are you penetrating a rated wall???

Most I see all pipe is ran in the Interstitial space
 
If the pipe is already in a rated ceiling floor assembly and does not penetrate a rated wall

It should be good to go
 
You need to follow the installation instructions of installing an additional layer of drywall and packing the stud cavity full of fiberglass or mineral wool insulation depending on the box used

https://dryerbox.com/firestop

The Dryerbox has been classified by Underwriters Laboratories, Inc. for models 350, 425, 480, 3D, and 4D for use in Through-Penetration Underwriters Laboratories Through Penetration Firestop System Firestop System Number W-L-7129.

Underwriters Laboratories Certifications Directory reference numbers: XHGK.R21933(US), XHGK7.R21933 (CANADA) and XHEZ.W-L-7129 (FIRESTOP SYSTEM). Cabinets For Use in Penetration Firestop Systems See UL Fire Resistance Directory <25XC>

Firestop System Number W-L-7129
Click here for a direct link to UL's online specifications for firestop system installation.
Click here for the Dryerbox Classification Listing (for Canada, here).

Quick One-Hour Wall Firestop Instruction Summary
These key components are noted on the instruction sheet that comes with every Dryerbox. The following are highlights to comply with the UL Classification for through-penetration firestop systems. To achieve a fire resistance rating (one-hour F & T) 2X6 framing is required. The Dryerbox unit must be installed in accordance with the UL Cabinet System listing.

Drywall requirements: An extra layer of type-X drywall must be installed in the ID of the stud cavity in which the Dryerbox is located. Drywall must be attached to nailers (minimum 1" X 2") located on the inside of the cavity wall studs. Secure nailers to wall framing at max 18 in. OC. The screws used to attach the inner layer of drywall shall be spaced a maximum of 18 inches apart.

Quick Reference Framing Configurations
Metal and wood framing configuration drawings used to assist with determining what additional materials are required in your particular 1-Hour rated demising wall assembly. Easy as: 1. Recognize your assembly. 2. Click to print out the respective engineer’s letter with UL’s Through-penetration Firestop System.

UL Labs Certification and Firestop Configuration for One Hour Wall
Studs and Insulation requirements - see table below.
Dryerbox Models Wall Studs Summary
350, 425, 3D and 4D Wood See Note 1
350, 425, 3D and 4D Steel See Note 2
480 Steel and Wood See Note 2

Note 1: The entire depth of stud cavity with Dryerbox® must be filled with R19 fiberglass batt insulation. Additional insulation shall be added within the cavity as necessary to completely fill all voids around the periphery of the Dryerbox and around the dryer vent pipe.

Note 2: The entire wall cavity containing the cabinet shall be tightly packed to full stud depth and cavity height with mineral wool batt insulation having a min density of 4 pcf. In addition, the wall stud cavities immediately adjacent to the cavity with the cabinet shall be insulated with min R13 glass fiber batt insulation (or min 4 pcf mineral wool batt material) for the full depth and height of the stud cavity.

fire_rated_assembly.jpg
Firestop Print Summary


Additional Information for Sprinklers and Corridors


 
Gonna resurrect this one for a bit.

Would you consider a dryer vent in this situation a through penetration or a membrane penetration or something else? I had a discussion today with someone who felt that the dryer pipe did not qualify as a through penetration because it did not penetrate the floor and ceiling of the assembly where I believe the intent of the definition is that the pipe enters and exits the assembly.
 
Michael Brown said:
Gonna resurrect this one for a bit.

Would you consider a dryer vent in this situation a through penetration or a membrane penetration or something else? I had a discussion today with someone who felt that the dryer pipe did not qualify as a through penetration because it did not penetrate the floor and ceiling of the assembly where I believe the intent of the definition is that the pipe enters and exits the assembly.
Click to expand...

If in the “void” space of the floor ceiling assembly

No Penetrartion, except at the dryer connection, which may or may not be a rated wall.
 
cda said:
If in the “void” space of the floor ceiling assembly

No Penetrartion, except at the dryer connection, which may or may not be a rated wall.
Click to expand...

Almost all of our dryers are not in rated walls. Would you then consider it a membrane penetration since we are penetrating into one side of the assembly at the top plate above the connection?
 
Michael Brown said:
Almost all of our dryers are not in rated walls. Would you then consider it a membrane penetration since we are penetrating into one side of the assembly at the top plate above the connection?
Click to expand...

Maybe

Good ahj answer

You would be running from a non rated void into a rated void assembly, but more than likely you are not going through any rated sheetrock ??? Would have to see where the rated meets the non rated

Yes just properly seal
 
DA0ADC99-C8D6-4CB9-89F6-7A11AD749ACE.jpeg


Like this

Appears where the vertical meets the horizontal wall, should be rated ???
 
Michael Brown said:
Gonna resurrect this one for a bit.

Would you consider a dryer vent in this situation a through penetration or a membrane penetration or something else? I had a discussion today with someone who felt that the dryer pipe did not qualify as a through penetration because it did not penetrate the floor and ceiling of the assembly where I believe the intent of the definition is that the pipe enters and exits the assembly.
Click to expand...

Yes, Michael, I will attempt to resurrect this topic again, and I will stay on track.

First, I am in a jurisdiction that does not support the use of dryer wrap. I am in agreement with the direction you are going, but I get there differently. I have expressed my frustration with IBC Chapter 7 in several posts in this forum. This will be no different.

Note, the end of your original post referred to Exception 1 of 714.4.1.1 and Exception 1 of 714.4.1.2. These do not apply to this installation. "conduits, pipes, tubes or vents" are not ducts. "Vent" has a definition in the IMC.

Starting with 2015 IBC, 717.6 references ducts that penetrate the ceiling membrane of a roof/ceiling assembly. This really should apply to the ceiling membrane of a floor/ceiling assembly as well but that's not how this is written. I cannot think of any good reason that it shouldn't apply, especially as I move forward. Just another fix to Chapter 7.

717.6.2 states that ducts that penetrate the ceiling membrane of a floor/ceiling or roof/ceiling (they got the floor/ceiling in this one!) be protected with a shaft or a ceiling radiation damper. I choose damper.

717.6.2.1 states that ceiling radiation dampers are not required if one of two apply. I choose two. "Where exhaust duct penetrations are protected in accordance with Section 714.4.1.2, are located in the cavity of a wall and do not pass through another dwelling unit or tenant space." .......... no damper required.

714.4.1.2 directs you to 714.4.1.1.2 which allows for the double top plate penetration of this 4" exhaust duct (because it is within the cavity of a wall and the double top plate is a continuation of the ceiling membrane of the floor/ceiling or roof/ceiling assembly) to be protected by an approved through-penetration firestop system.

Good luck finding one to match. Most systems are shown to penetrate the ceiling membrane and the floor. I haven't been able to find one that only penetrated the ceiling membrane and had the duct turn 90 degrees. Years ago, we had a fire protection engineer provide us with one that we used (approved). It was no different than many of the systems that we've seen and approved from the NRTL's except that it didn't penetrate the floor. The primary protection was simply annular space materials, no damper and no duct wrap required. Show me a NRTL system using a 4" duct that penetrates the ceiling and the floor, and I will most likely approve it for this application.

There is much similarity in 717.6.1 Exception.
 
rgrace said:
Yes, Michael, I will attempt to resurrect this topic again, and I will stay on track.

First, I am in a jurisdiction that does not support the use of dryer wrap. I am in agreement with the direction you are going, but I get there differently. I have expressed my frustration with IBC Chapter 7 in several posts in this forum. This will be no different.

Note, the end of your original post referred to Exception 1 of 714.4.1.1 and Exception 1 of 714.4.1.2. These do not apply to this installation. "conduits, pipes, tubes or vents" are not ducts. "Vent" has a definition in the IMC.

Starting with 2015 IBC, 717.6 references ducts that penetrate the ceiling membrane of a roof/ceiling assembly. This really should apply to the ceiling membrane of a floor/ceiling assembly as well but that's not how this is written. I cannot think of any good reason that it shouldn't apply, especially as I move forward. Just another fix to Chapter 7.

717.6.2 states that ducts that penetrate the ceiling membrane of a floor/ceiling or roof/ceiling (they got the floor/ceiling in this one!) be protected with a shaft or a ceiling radiation damper. I choose damper.

717.6.2.1 states that ceiling radiation dampers are not required if one of two apply. I choose two. "Where exhaust duct penetrations are protected in accordance with Section 714.4.1.2, are located in the cavity of a wall and do not pass through another dwelling unit or tenant space." .......... no damper required.

714.4.1.2 directs you to 714.4.1.1.2 which allows for the double top plate penetration of this 4" exhaust duct (because it is within the cavity of a wall and the double top plate is a continuation of the ceiling membrane of the floor/ceiling or roof/ceiling assembly) to be protected by an approved through-penetration firestop system.

Good luck finding one to match. Most systems are shown to penetrate the ceiling membrane and the floor. I haven't been able to find one that only penetrated the ceiling membrane and had the duct turn 90 degrees. Years ago, we had a fire protection engineer provide us with one that we used (approved). It was no different than many of the systems that we've seen and approved from the NRTL's except that it didn't penetrate the floor. The primary protection was simply annular space materials, no damper and no duct wrap required. Show me a NRTL system using a 4" duct that penetrates the ceiling and the floor, and I will most likely approve it for this application.

There is much similarity in 717.6.1 Exception.
Click to expand...
rgrace said:
Yes, Michael, I will attempt to resurrect this topic again, and I will stay on track.

First, I am in a jurisdiction that does not support the use of dryer wrap. I am in agreement with the direction you are going, but I get there differently. I have expressed my frustration with IBC Chapter 7 in several posts in this forum. This will be no different.

Note, the end of your original post referred to Exception 1 of 714.4.1.1 and Exception 1 of 714.4.1.2. These do not apply to this installation. "conduits, pipes, tubes or vents" are not ducts. "Vent" has a definition in the IMC.

Starting with 2015 IBC, 717.6 references ducts that penetrate the ceiling membrane of a roof/ceiling assembly. This really should apply to the ceiling membrane of a floor/ceiling assembly as well but that's not how this is written. I cannot think of any good reason that it shouldn't apply, especially as I move forward. Just another fix to Chapter 7.

717.6.2 states that ducts that penetrate the ceiling membrane of a floor/ceiling or roof/ceiling (they got the floor/ceiling in this one!) be protected with a shaft or a ceiling radiation damper. I choose damper.

717.6.2.1 states that ceiling radiation dampers are not required if one of two apply. I choose two. "Where exhaust duct penetrations are protected in accordance with Section 714.4.1.2, are located in the cavity of a wall and do not pass through another dwelling unit or tenant space." .......... no damper required.

714.4.1.2 directs you to 714.4.1.1.2 which allows for the double top plate penetration of this 4" exhaust duct (because it is within the cavity of a wall and the double top plate is a continuation of the ceiling membrane of the floor/ceiling or roof/ceiling assembly) to be protected by an approved through-penetration firestop system.

Good luck finding one to match. Most systems are shown to penetrate the ceiling membrane and the floor. I haven't been able to find one that only penetrated the ceiling membrane and had the duct turn 90 degrees. Years ago, we had a fire protection engineer provide us with one that we used (approved). It was no different than many of the systems that we've seen and approved from the NRTL's except that it didn't penetrate the floor. The primary protection was simply annular space materials, no damper and no duct wrap required. Show me a NRTL system using a 4" duct that penetrates the ceiling and the floor, and I will most likely approve it for this application.

There is much similarity in 717.6.1 Exception.
Click to expand...

rgrace, thank you. I followed the "must comply with's" again this morning and it only reinforced my belief that the dryer wrap is not required. I also happened upon the UL 1479/ ASTM E814 detail that is referenced several times in chapter 7. The one I found shows the duct turning 90 degrees upon entry into the assembly. I have attached a copy. Let me know what you think.

I would also like to thank everyone else who has responded. I appreciate having a place to discuss code interpretation with knowledgeable individuals such as yourselves.
 

Attachments

  • Through-penetration Firestop Systems_ XHEZ.F-C-7060 - UL Product Spec.pdf
    273.6 KB · Views: 22
Revive with a different condition. 2018 IBC/IMC, R2, VB, 3 story
Plans indicate the dryer exhaust running vertically to the rated ceiling within the room, not within the wall. The duct then penetrates the lower membrane of the 1-hr horizontal assembly. IMC prohibits dampers in dryer ducts, IBC requires ceiling radiation dampers. Is the only option to provide a rated floor/ceiling assembly tested with dampers as permitted by IBC 717.6.2 #2, exc. #1? There is also a bathroom exhaust fan, but I assume that can be provided with a damper.

1712086630816.png
 
Sifu said:
Revive with a different condition. 2018 IBC/IMC, R2, VB, 3 story
Plans indicate the dryer exhaust running vertically to the rated ceiling within the room, not within the wall. The duct then penetrates the lower membrane of the 1-hr horizontal assembly. IMC prohibits dampers in dryer ducts, IBC requires ceiling radiation dampers. Is the only option to provide a rated floor/ceiling assembly tested with dampers as permitted by IBC 717.6.2 #2, exc. #1? There is also a bathroom exhaust fan, but I assume that can be provided with a damper.

View attachment 13228
Click to expand...
Penetrate the wall and not the ceiling. Complies with Exception #3 to IBC Sec. 717.5.4.
 
Sorry, re-read my post, the option would be tested without dampers.
 
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