Duct penetration of existing floor/ceiling

[Scott Dillow]

Curious what others opinions are on this. Code is 2018 IEBC & IBC. I have a two-story wood-frame dormitory style youth detention facility with a basement (Type VB construction). We are adding a single-user toilet room off a dayroom on the first floor (So Level 2 alteration). To get air into the room we are tapping off a supply duct in the basement and running a 4x6 duct up into the new toilet room wall cavity and then above a suspended ceiling to a diffuser. The existing floor/ceiling assembly does not appear to be rated, and under VB does not have a rating requirement, but I assume we'd need a minimum 1-hour duct damper? Section 717.6.1 does not seem to permit a fire damper because we are an I-3 occupancy. As this duct would only be connecting 2 floors, I would think a fire damper should cover it. Building is not sprinklered. What am I missing?

 

[classicT]

I'm not sure that a definitive answer can be given without identifying wherein the fire and smoke barriers are provided. Undoubtedly, given the I-3 occupancy, there will be some compartmentalization. Particularly if there is any mixed use within the building.

Something that initially comes to mind is the special requirements from Ch. 4.

2021 IBC (non-amended)​

408.5 Protection of Vertical Openings​

Any vertical opening shall be protected by a shaft enclosure in accordance with Section 713, or shall be in accordance with Section 408.5.1.

408.5.1 Floor Openings​

Openings in floors within a housing unit are permitted without a shaft enclosure, provided that all of the following conditions are met:​

1. The entire normally occupied areas so interconnected are open and unobstructed so as to enable observation of the areas by supervisory personnel.
2. Means of egress capacity is sufficient for all occupants from all interconnected cell tiers and areas.
3. The height difference between the floor levels of the highest and lowest cell tiers shall not exceed 23 feet (7010 mm).
4. Egress from any portion of the cell tier to an exit or exit access door shall not require travel on more than one additional floor level within the housing unit.

408.5.2 Shaft Openings in Communicating Floor Levels​

Where a floor opening is permitted between communicating floor levels of a housing unit in accordance with Section 408.5.1, plumbing chases serving vertically staked individual cells contained with the housing unit shall be permitted without a shaft enclosure.​

 

[classicT]

2021 IBC (non-amended)​

408.5 Protection of Vertical Openings​

Any vertical opening shall be protected by a shaft enclosure in accordance with Section 713, or shall be in accordance with Section 408.5.1.

408.5.1 Floor Openings​

Openings in floors within a housing unit are permitted without a shaft enclosure, provided that all of the following conditions are met:

1. The entire normally occupied areas so interconnected are open and unobstructed so as to enable observation of the areas by supervisory personnel.
2. Means of egress capacity is sufficient for all occupants from all interconnected cell tiers and areas.
3. The height difference between the floor levels of the highest and lowest cell tiers shall not exceed 23 feet (7010 mm).
4. Egress from any portion of the cell tier to an exit or exit access door shall not require travel on more than one additional floor level within the housing unit.

408.5.2 Shaft Openings in Communicating Floor Levels​

Where a floor opening is permitted between communicating floor levels of a housing unit in accordance with Section 408.5.1, plumbing chases serving vertically staked individual cells contained with the housing unit shall be permitted without a shaft enclosure.

Noticed your input on the 2018 IBC. Note that the code language is the same in the 2018 Pennsylvania Building Code is the same as the 2021 IBC.

 

[classicT]

At minimum, it would appear that the floor in question should be at least a smoke barrier per the following.

2018 Pennsylvania Building Code​

408.6 Smoke Barrier​

Occupancies in Group I-3 shall have smoke barriers complying with Sections 408.6 and 709 to divide every story occupied by residents for sleeping, or any other story having an occupant load of 50 or more persons, into not fewer than two smoke compartments.
Exception: Spaces having a direct exit to one of the following, provided that the locking arrangement of the doors involved complies with the requirements for doors at the smoke barrier for the use condition involved:

1. A public way.
2. A building separated from the resident housing area by a 2-hour fire-resistance-rated assembly or 50 feet (15 240 mm) of open space.
3. A secured yard or court having a holding space 50 feet (15 240 mm) from the housing area that provides 6 square feet (0.56 m2) or more of refuge area per occupant, including residents, staff and visitors.

 

[north star]

# ~ #

Is there a Return Air Duct in this mix ?

# ~ #

 

[mtlogcabin]

Returns are not permitted in a restroom. It should have an exhaust duct to the outside.

 

[Scott Dillow]

# ~ #

Is there a Return Air Duct in this mix ?

# ~ #

No return. Just an exhaust.

 

[Scott Dillow]

At minimum, it would appear that the floor in question should be at least a smoke barrier per the following.

2018 Pennsylvania Building Code​

408.6 Smoke Barrier​

Occupancies in Group I-3 shall have smoke barriers complying with Sections 408.6 and 709 to divide every story occupied by residents for sleeping, or any other story having an occupant load of 50 or more persons, into not fewer than two smoke compartments.
Exception: Spaces having a direct exit to one of the following, provided that the locking arrangement of the doors involved complies with the requirements for doors at the smoke barrier for the use condition involved:

1. A public way.
2. A building separated from the resident housing area by a 2-hour fire-resistance-rated assembly or 50 feet (15 240 mm) of open space.
3. A secured yard or court having a holding space 50 feet (15 240 mm) from the housing area that provides 6 square feet (0.56 m2) or more of refuge area per occupant, including residents, staff and visitors.

We are figuring on filling the annular space around the duct to prevent smoke and gas passage.

 

[classicT]

We are figuring on filling the annular space around the duct to prevent smoke and gas passage.

That may work, if the floor is non-rated and meeting an exception to 408.6.

I would highly suggest having the complete layout of all fire and smoke assemblies prior to proceeding. Simply cannot be sure what is necessary without.

 

[Scott Dillow]

I'm not sure that a definitive answer can be given without identifying wherein the fire and smoke barriers are provided. Undoubtedly, given the I-3 occupancy, there will be some compartmentalization. Particularly if there is any mixed use within the building.

Something that initially comes to mind is the special requirements from Ch. 4.

2021 IBC (non-amended)​

408.5 Protection of Vertical Openings​

Any vertical opening shall be protected by a shaft enclosure in accordance with Section 713, or shall be in accordance with Section 408.5.1.

408.5.1 Floor Openings​

Openings in floors within a housing unit are permitted without a shaft enclosure, provided that all of the following conditions are met:​

1. The entire normally occupied areas so interconnected are open and unobstructed so as to enable observation of the areas by supervisory personnel.
2. Means of egress capacity is sufficient for all occupants from all interconnected cell tiers and areas.
3. The height difference between the floor levels of the highest and lowest cell tiers shall not exceed 23 feet (7010 mm).
4. Egress from any portion of the cell tier to an exit or exit access door shall not require travel on more than one additional floor level within the housing unit.

408.5.2 Shaft Openings in Communicating Floor Levels​

Where a floor opening is permitted between communicating floor levels of a housing unit in accordance with Section 408.5.1, plumbing chases serving vertically staked individual cells contained with the housing unit shall be permitted without a shaft enclosure.​

As our scope doesn't go beyond adding a single-user toilet room off a dayroom, we have not checked what the existing smoke separation situation is, room-to-room or floor-to-floor. All the sleeping rooms are on the second floor and we are not doing any work there. Just doesn't make sense to have a shaft from the floor to the terminus of our duct above our toilet room ceiling (but below the existing building floor/ceiling assembly) that ends in a fire damper when a fire damper can just be added at the floor line.

 

[classicT]

we have not checked what the existing smoke separation situation is

Then you cannot get an answer as to what is required by code. This is critical information.