# Garage Ventilation R-2 Occupancy



## kluth (Feb 16, 2011)

I' m new, but going to jump right in. Our department requested an interpretation from the ICC regarding garage ventilation in R-2 occupancies. I would like to hear responses from others regarding the proposed question(s). I will refrain from indicating my opinion at this time. The interpretation request is as follows:

_Code Reference: International Building Code International Mechanical Code_

_Code Edition: 2006 IBC and 2006 IMC_

_Code Section: IBC Sec. 1203.4 and IMC Sec. 401.2_

_Questions: We have a situation where we have a common, multi-stall garage attached to a multi-family residential condominium. The garage is a private garage that is used for the storage of private or pleasure-type motor vehicles and is considered a U occupancy (IBC Section 406.1.2). The interior of the garage is open with no separation walls between stalls. Each stall is provided with a separate overhead door opening. IBC Section 1203.4 and IMC Section 401.2 appear to indicate that ventilation can be provided by natural means. The overhead door for each stall satisfies the required minimum openable area to the outdoors (IBC Sec. 1203.4.1 and IMC Sec. 402.2). Does this garage need to be provided with mechanical ventilation? Does IBC Section 1203.4.2 and IMC Section 401.6 require a mechanical exhaust system because of the exhaust fumes from the motor vehicles? _

The only "incorrect" statement above is relating to the garage doors. There are actually two garage doors for four stalls, not "Each stall is provided with a separate overhead door opening", as written. What do you guys think?

Kirk


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## mtlogcabin (Feb 16, 2011)

I don't believe the garage is an occupiable space under the IBC so 1203.4 would not be applicable

OCCUPIABLE SPACE. A room or enclosed space designed for human occupancy in which individuals congregate for amusement, educational or similar purposes or in which occupants are engaged at labor, and which is equipped with means of egress and light and ventilation facilities meeting the requirements of this code.


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## Frank (Feb 16, 2011)

S-2 use but natural ventilation is adequate


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## mtlogcabin (Feb 16, 2011)

Since you are in a cold climate area I would be concerned with a tenant using the remote car starter and warming their cars during the winter months. Exhaust could build up and enter into the living areas. I would be looking towards a mechanical exhaust activated by an exhust sensor. Look at section 404.


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## PORTEOUS (Feb 16, 2011)

Agree w/ cabin, nat. venting meets intent but as here in MT, garage doors are often closed in winter allowing exhaust to build-up, I would also suggest mechanical ventilation


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## Dr. J (Feb 16, 2011)

> The garage is a private garage that is used for the storage of private or pleasure-type motor vehicles and is considered a U occupancy (IBC Section 406.1.2).





> S-2 use but natural ventilation is adequate


I think it comes down to the use group.  If it is a private garage, it is already a fairly limited size.  I guess it is ***-u-me-d that the individual owner is not stupid enough to run their car in a closed garage which he has control over.  No ventilation (natural or mechanical) is required for a private garage, regardless of openings.

The "S2" assumes a more uncontrolled population.  S2 must be ventilated.  If it does not meet the definition of "open" it is "enclosed" and needs mechanical ventilation per IMC 404.  The overhead doors sound like it prevents it from meeting the interior openness test.

The call between U and S2 is an interesting one.  No where does it say U is limited to single building owners/occupants.  All that is required is that the vehicles do not have a sign on them (private, not commercial), and limited to 1000 or 3000 sf.  I could see the call going towards S2 because it is not "private" in the sense that multiple people have access, rather than a single person, but this is coloring outside the lines a bit.  The question is not if this particular U occupancy Private Garage needs ventilation - no Private Garage ever requires ventilation.  The question is S2 or U.


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## kluth (Feb 17, 2011)

Dr. J said:
			
		

> The question is not if this particular U occupancy Private Garage needs ventilation - no Private Garage ever requires ventilation.  The question is S2 or U.


So, when are the exhaust rates in Table 403.3 applicable?

Table 403.3

*Private dwellings, single and multiple*

Garages, common for multiple units

.75 cfm/ft 2

Garages, separate for each dwelling

100 cfm per car

Footnote b indicates an exhaust system and no recirculation.


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