# Makeup air from corridor



## mark handler (Sep 20, 2019)

International Code: 2015 International Mechanical Code
https://www.iccsafe.org/building-safety-journal/bsj-technical/talking-in-code-exit-access-corridor/
Section: 601.2
*Question: *Can a corridor in a Group R-2 apartment building supply makeup air to a dwelling unit to serve as the makeup air for the bathroom exhaust for a bathroom located in the dwelling unit?

*Answer: *The corridor in question is considered an exit access corridor. Section 601.2 does not permit an exit access corridor to serve as a supply, return, exhaust, relief or ventilation air duct. Exception #1 of Section 601.2, however, allows the corridor to supply air to be used for makeup air in rooms that open directly onto the corridor such as toilet rooms, bathrooms and janitor closets. These rooms would have an exhaust fan and the corridor would supply the makeup air for the exhaust fan. There would have to be an equal amount of outdoor air supplied directly to the corridor that would equal the amount of makeup air supplied by the corridor to the adjacent toilet room or similar space.
In your situation, the room that opens directly into the corridor is the dwelling unit. The room that requires the exhaust is the toilet room in the dwelling unit. Since the makeup air would have to go through the dwelling unit to get to the toilet room, the toilet room is not considered to be opening directly onto the corridor and, therefore, this Exception #1 of Section 601.2 would not apply.


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## e hilton (Sep 20, 2019)

From a practical perspective, to get the makeup air to the exhaust fan, the entrance door at the corridor would need a gap at the bottom to let air in.  And noise.  Who would wan5 that?


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## tmurray (Sep 20, 2019)

How would the make-up air be supplied by the corridor, while also controlling the movement of smoke and flame?

Is there no requirement for a fire separation between the corridor and suites?


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## cda (Sep 20, 2019)

Dampers required


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## ADAguy (Sep 20, 2019)

Should have been considered during initial planning.


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## Builder Bob (Sep 20, 2019)

Fire rated access corridor?

If fire rated access corridor, the simple answer is not allowed. 

BTW more than dampers would be required - Smoke dampers as well - but still not code compliant.


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## cda (Sep 20, 2019)

Quote


208 IBC
717.5.4 Fire partitions.
Ducts and air transfer openings that penetrate fire partitions shall be protected with listed fire dampers installed in accordance with their listing.

Exceptions: In occupancies other than Group H, fire dampers are not required where any of the following apply:

1. Corridor walls in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 and the duct is protected as a through penetration in accordance with Section 714.

717.5.4.1 Corridors.
Duct and air transfer openings that penetrate corridors shall be protected with dampers as follows:

1. A corridor damper shall be provided where corridor ceilings, constructed as required for the corridor walls as permitted in Section 708.4, Exception 3, are penetrated.

2. A ceiling radiation damper shall be provided where the ceiling membrane of a fire-resistance-rated floor-ceiling or roof-ceiling assembly, constructed as permitted in Section 708.4, Exception 2, is penetrated.

3. A listed smoke damper designed to resist the passage of smoke shall be provided at each point a duct or air transfer opening penetrates a corridor enclosure required to have smoke and draft control doors in accordance with Section 716.2.2.1.

Exceptions:

1. Smoke dampers are not required where the building is equipped throughout with an approved smoke control system in accordance with Section 909, and smoke dampers are not necessary for the operation and control of the system.

2. Smoke dampers are not required in corridor penetrations where the duct is constructed of steel not less than 0.019 inch (0.48 mm) in thickness and there are no openings serving the corridor.

#4


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## cda (Sep 20, 2019)

https://www.thebuildingcodeforum.com/forum/threads/r-1-corridor-wall-penetration-question.23343/


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## rgrace (Sep 23, 2019)

Guess where this came from .... I used this as an example once to other code officials. It didn't go over well, so as a team player, I don't promote it anymore. 

*Q*
A hotel room is 250 ft2 with a 50 ft2 bathroom. The bathroom is exhausted with an exhaust fan that runs continuously. Makeup for the exhaust comes from a pressurized corridor, which is supplied with 100% outdoor air, through the hotel room door that is located adjacent to the bathroom. The room is assumed to have two occupants. What are the ventilation requirements for this room?
*
A*
First calculate the breathing zone airflow rate for the hotel room using the design occupancy, floor area, and ventilation rates from Table ***:

Vbz          = RpPz + RaAz
                = 5*2 + 0.06*250
                = 25 cfm

Next determine the zone air distribution effectiveness from Table ***. The last row in this table was specifically provided to address this design. The makeup air from the corridor will substantially short-circuit the space so the air distribution effectiveness is 0.5.
Next, calculate the minimum zone outdoor airflow (Voz) rate:

Voz        = Vbz\Ez
              = 25\0.5
              = 50 cfm

To provide this zone outdoor airflow rate using the toilet exhaust, the toilet exhaust rate must be at least 50 cfm. This rate would need to be greater if the corridor contained both outdoor air and recirculated air (_my note; corridor must be provided with dedicated unit; cannot provide air to other locations and then recirculate it; that's not permitted_), rather than 100% outdoor air as assumed in this example. Per Table ***, the exhaust rate would only have to be 25 cfm for continuous fan operation to meet section ***, but the larger rate is required in this case for the fan to also provide space ventilation. The exhaust fan must run whenever the space is expected to be occupied so an exhaust fan manually controlled by a wall switch would not comply.


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## Paul Sweet (Sep 23, 2019)

Logically, using a pressurized corridor to supply makeup air shouldn't present a danger.  NFPA 80 par. 4.8.4.1 allows 3/4" clearance at the bottom of a door.  Fire doors are tested with a neutral plane 1/3 of the way up the door (IBC 716.6.1) so the bottom of the door is under negative pressure and smoke shouldn't escape into the corridor.  However, IMC 601.2 limits this to rooms opening directly into the corridor.


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