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Garage Open Air Calculations

iodinej

Member
Joined
Dec 18, 2011
Messages
2
I am designing a garage, and trying to achieve natural ventilation. I think I have achieved the required 20% open, as well as 40% perimeter open as per IBC 2006, but what if your garage is really deep? It seems like if you have a very large garage, if you're 150' from the perimeter, air is not likely getting in to the inside of the garage. Is there any requirements, i.e. maximum distance to perimeter opening req'd before needing to implement mechanical ventilation?
 
Just want to say welcome

Have no knowledge about garages

How did you find us????
 
I've been trying to track down code information, and came across this forum.
 
2006 INTERNATIONAL BUILDING CODE®

406.3.3.1 Openings. For natural ventilation purposes, the exterior side of the structure shall have uniformly distributed openings on two or more sides. The area of such openings in exterior walls on a tier must be at least 20 percent of the total perimeter wall area of each tier. The aggregate length of the openings considered to be providing natural ventilation shall constitute a minimum of 40 percent of the perimeter of the tier. Interior walls shall be at least 20 percent open with uniformly distributed openings.

Exception: Openings are not required to be distributed over 40 percent of the building perimeter where the required openings are uniformly distributed over two opposing sides of the building.

Don't worry about the depth, worry about the Interior walls at least 20 percent open
 
If you don't meet the requirements you and Mark described, then you fall under the enclosed parking garages, and Section 404 of the 2006 IMC would then apply. It appears you are on the correct path. I am not sure if there any further applicable requirements in the ANSI/ASHRAE STANDARD 62.1-2004, but you may want to check that standard, as it has come into play, and proven helpful, in other areas such as recirculation limitations, etc.
 
Welcome iodinej, natural ventilation requires that the over all openings need to equal 4% of the floor surface. IMC 402.2.

All bets off if it used for almost anything other than parking, then mechanical ventilation is required.
 
gbhammer said:
welcome iodinej, natural ventilation requires that the over all openings need to equal 4% of the floor surface. Imc 402.2. All bets off if it used for almost anything other than parking, then mechanical ventilation is required.
Do not concider a garage as occupied space? IMC 401?
 
IMC is not applicable to the determination of open vs enclosed parking garage. Only if a garage does not meet the requirements for an "open" parking garage in IBC 406.3 does mechanical ventilation in compliance with the IMC come into play. The only time percentage of floor area or distance from an opening is a factor is the area and height increasses of 403.6.

So, yes, it is possible for a Type 1A garage to have a million square foot floor plate with openings 1000 feet from the most remote part of the floor without either spinklers, mechanical ventilation, or interior airshafts.
 
mark handler said:
Do not concider a garage as occupied space? IMC 401?
IMC 401.2 Every occupied space shall be ventilated...

If a garage is not considered occupied why would the IBC section 406.3.3.1 (open parking) require openings for natural ventilation, and 406.4.2 (enclosed parking) require mechanical ventilation?
 
gbhammer said:
IMC 401.2 Every occupied space shall be ventilated...If a garage is not considered occupied why would the IBC section 406.3.3.1 (open parking) require openings for natural ventilation, and 406.4.2 (enclosed parking) require mechanical ventilation?
Just asking the questions.
 
Please do not go down the road that a parking garage is occupied. What then about IBC 1204 requiring occupied spaces to be heated to 68 deg, or 1205 requiring 10 fc of lighting, or the IECC building envelope requirements?
 
Dr. J said:
Please do not go down the road that a parking garage is occupied. What then about IBC 1204 requiring occupied spaces to be heated to 68 deg, or 1205 requiring 10 fc of lighting, or the IECC building envelope requirements?
I don't want to :beatdhrs but:IBC 1204.1 exception: ... not associated with human comfort.

You would perhaps call the open garage a building?

IBC 1203.1 Buildings shall be provided with natural... or mechanical ventilation

IBC 311.1 Storage Group S. Storage Group S occupancy... (Last time I looked an occupancy is a space that can, well be occupied. Perhaps not comfortably but none the less if you can enter the structure/building you are occupying it.)

And

If you occupy it, it needs to be lit IBC 1205.

At least that is how we look at it in our jurisdiction. :D
 
gbhammer said:
IBC 311.1 Storage Group S. Storage Group S occupancy... (Last time I looked an occupancy is a space that can, well be occupied. Perhaps not comfortably but none the less if you can enter the structure/building you are occupying it.) And

If you occupy it, it needs to be lit IBC 1205.

At least that is how we look at it in our jurisdiction. :D
Kind of like how warehouses are inhabited/occupied by boxes (see futurama, season 01, episode 5, for further explaination of places inhabited by stuff), parking garages are inhabited/occupied by cars...and the people who leave and retrieve those items stored there. An open air S-2 parking garage is still an inhabited building, albeit exempt from the IMC by the IBC qualifications.
 
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Originally Posted by Dr. J

Please do not go down the road that a parking garage is occupied. What then about IBC 1204 requiring occupied spaces to be heated to 68 deg, or 1205 requiring 10 fc of lighting, or the IECC building envelope requirements?

I don't want to :beatdhrs but:
The answer is in

2009 IBC 406.3.12 Ventilation.

Ventilation, other than the percentage of openings specified in Section 406.3.3.1, shall not be required.

 
Idoinej.

Once again welcome to the forum

It does have people with years of experience

But they do not always agree, which is good
 
* * * *

I think that there needs to be some more definitive

descriptions of habitable spaces, ...inhabitable

[ spaces / areas / rooms ] & ...structures vs. buildings.



* * * *
 
Dr. J said:
Please do not go down the road that a parking garage is occupied. What then about IBC 1204 requiring occupied spaces to be heated to 68 deg, or 1205 requiring 10 fc of lighting, or the IECC building envelope requirements?
I have to agree with GB, the road isn't that bumpy. 1204.1 is NA. 1006 & 1205 are still applicable. 2009 IECC 101.5.2 Low Energy Buildings. ....shall be exempt from the building thermal envelope provisions of this code: 2. Those that do not contain conditioned space

2006 IBC 1204.1 Exception for interior spaces where primary purpose is not associated with human comfort.
 
mtlogcabin said:
The answer is in 2009 IBC 406.3.12 Ventilation.

Ventilation, other than the percentage of openings specified in Section 406.3.3.1, shall not be required.

*Mechanical ventilation systems are not required in a structure that is inherently open to the exterior atmosphere.

So long as you meet the definition of an open parking garage and all of its requirements then you’re good to go, if you do not meet those requirements then you can't meet the definition and the garage falls under all the requirements for an S-2 building.
 
Dr. J said:
Please do not go down the road that a parking garage is occupied. What then about IBC 1204 requiring occupied spaces to be heated to 68 deg, or 1205 requiring 10 fc of lighting, or the IECC building envelope requirements?
An open parking garage as defined in the code is not a room or interior space

OCCUPIABLE SPACE. A room or enclosed space designed for human occupancy ............and which is equipped with means of egress and light and ventilation facilities meeting the requirements of this code.

1204.1 Equipment and systems.

Interior spaces intended for human occupancy shall be provided with active or passive space-heating systems capable of maintaining a minimum indoor temperature of 68°F (20°C) at a point 3 feet (914 mm) above the floor on the design heating day.

Exception: Interior spaces where the primary purpose is not associated with human comfort.

1205 would be applicable

JMHO
 
For the purposes of the OP, I think I am seeing that MT, and Papio say that while a Parking Garage is considered Occupied/Occupiable, they do not have to meet the provisions of IMC 402.2. and 402.3 (percentage of floor area and adjacent space). Therefore, the million sf garage with openings 1000 ft away is still legal, right?
 
Now that we got iodinej's question out of the way, I hope you really are not requiring parking garage lighting levels 10 times higher than the IESNA levels. IBC 1205 requires 10 fc, whereas IESNA is 1 fc. IECC, which is based on IESNA lighting values, has a LPD of 0.3 w/sf for parking garage lighting. How do you meet that with lighting levels 10 times as high as the energy code is expecting?
 
Ah, in this jurisdiction they just keep deleting most of the IECC, out here people like the freedom of choice. Most of everyone feels like global warming climate change is a joke/hoax perpetrated by corrupt legislature to line the pockets of contributors and to create golden parachutes.
 
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