View Full Version : Garage Vents

Charles Smith
07-10-2007, 07:11 AM
I have been searching for requirements for residential garage ventilation.
Typically there will be two (2) 12 inch louvered metal vents co-located just above the sill plate and usually near the vehicle entry end of the garage.

As I understand this is required due to combustible storage such as paints, thinners, gasoline as well as the potential car running with vehicle door closed (not recommended).

These are not for combustible gas appliances located in a garage.
Those have there own "hi and low" combustion air supply vents as well as 18 inch height above the garage floor requirement.

The local code enforcement is inconsistent; some new constuction has them and some don not. So the picky home inspector still calls it out.

Any code or inspect info would be appreciated.

"Santa Fe Home Inspection with an altitude"

John Arnold
07-10-2007, 09:28 AM
Typically there will be two (2) 12 inch louvered metal vents co-located just above the sill plate and usually near the vehicle entry end of the garage.
Must be a regional thing. We don't have those around here.

Jerry McCarthy
07-10-2007, 01:27 PM
That venting you're referring to was required in the UBC up until around the 1970s and we called them "suicide vents." I always installed them at the bottom of the garage overhead door and did so even after they where no longer required. MaMa puts baby in car that’s in garage and then goes back inside house to answer or make phone call while motor is running and forgets about baby. I think it's a big mistake to remove them as a code requirement.

Phillip Stojanik
07-10-2007, 03:01 PM
Sounds like a local code thing not seen around here.

Rick Hurst
07-10-2007, 04:45 PM

Once on one of the TAREI seminars, we went out on one of those field inspection trips and actually seen the garage vents down in the Austin area on some new construction.

First time I had even seen them, and someone called them "suicide vents" is where I first heard that term. I'm sure they are for garage ventilation and sound like a great idea. Seeing them on a slab home on the exterior wall was strange. At first we thought it was a P&B foundation.

Never have seen them elsewhere in State.

Matt Fellman
07-10-2007, 06:26 PM
I've never seen such a thing in my area (Oregon) but have to ask.... Do you really think they would work? Is that enough ventilation to exchange enough air to keep car exhaust from killing someone inside, as in the example given?

I'd think that a lot of testing, etc. went into it but then when I hear it was from the 70's I'm not so sure. I don't think anyone in that decade really understood airflow... perfect example would be the 1" holes drilled the soffits for attic ventilation.

Or, the louvered,screened and flap covered foundation vents?

Like mentioned, it's not really ever good idea to run the car inside with the doors closed and I know anything helping the ventilation is good. I'm more just curious if it would help.... hard to test though :)

Another one along the same lines is the clip on the damper with a gas line to a fireplace. How much would that really help? Again, not one I want to test... more just thinking out loud.

Phillip Stojanik
07-10-2007, 07:54 PM

Thinking back, I do recall seeing such vents one time only here in the Houston area in a new construction home. I remember thinking the same thing you did when I first saw them from the outside -- Wow a crawlspace! But no, turned out to just be vents into the attached garage down low along the side.

Personally I don't see how enough air would be exchanged by a passive vent system as described to keep up with the exhaust fumes of a running automobile in an otherwise closed-up garage.

Such vents might slow the buildup of CO somewhat, but I don't see it keeping up with CO accumulation unless the auto exhaust pipe was really close and pointed right at the vent.

There may however be some utility in such vents for keeping down the heavier-than-air accumulation of other fumes in the garage from stored items (gas cans, fertilizers, paints and so on).

By the way, didn't someone here post some photos not long ago of a garage that literally blew up from automobile exhaust accumulation that eventually ignited in a close garage?

Eric Shuman
07-11-2007, 06:48 AM
Yeah Rick,

I occasionally see these vents here in Austin, even on new construction. To my knowledge after reviewing the city adjustments to the 2000 IRC (yes, we are still on the 2000 IRC even though homebuilding is at an all time high here!) they are not required.

I don't see a problem with them but don't really see an enormous benefit to them either unless some HVAC equipment is in the garage, and even then, that equipment usually takes its combustion air from the attic or exterior.



Jerry Peck
07-11-2007, 09:45 AM
They were (meaning past tense) required by the South Florida Building Code, however, when that went to bed and was replaced with the Florida Building Code, that requirement was lost.

I agree with those who state it was a bad thing for that requirement to be dropped.

We always called them suicide vents too.