Ventilation Code Requirement - "Relief Opening"

[Gurvy522]

So I'm in the process of obtaining a permit for a new, detached masonry (brick and block) garage, and have run into a bit of a snag on a newer code requirement as it pertains to ventilation requirements in my jurisdiction (Chicago). I am working with an architect, but I guess this is a newer code change here and this is the first time he's dealing with it - along with the fact that this garage will be conditioned via a heat pump.

In Chicago, apparently, we have a "1.0 sf of opening per car" ventilation requirement categorized as a "relief opening" - for any garage with less than a 6-car capacity.

The code states RO's are "any duct that connects a room to the outside", and that a horizontal run cannot exceed 5ft and the cross-sectional area velocity shall not exceed 800 feet per minute.

But since my plan is to condition the garage, I wonder if there is a solution anyone here has looked at (or implemented) to achieve this, aside from your standard-fare roof vents or foundation vents? Do any other jurisdictions even have a requirement like this? I mean Chicago has always been a bit of code-hell, but this a detached garage. Ventilation for things like car fumes can be achieved with, I dunno.... maybe just opening a garage door? Hah. Just venting (pun intended) a bit here, but wondering if anyone has run into a requirement like this, and how they approached it?

Chicago 18-28-403.10 for reference.

 

[duneslider]

Well, I think this is absolutely crazy, but I guess you gotta do what they say. You are also combining multiple things. The 5' horizontal run stuff only applies to mechanical venting which you aren't required to do. You just need to provide 1cuft of vent per car. If it were me, I would pick a location to put the vent and build it to a size that a damper could later be put in its place. Have the opening for inspection then swap out for a closeable damper to use when you will be conditioning the space. I haven't heard of this sort of req any place else for residential garages, commercial spaces may require ventilation.

Good luck with this stuff!

 

[PCustoms]

You're paying an architect, what is the scope of their work?

I would expect whomever is designing my building (not just the aesthetics) to design a building that meets the code

 

[Gurvy522]

Well, I think this is absolutely crazy, but I guess you gotta do what they say. You are also combining multiple things. The 5' horizontal run stuff only applies to mechanical venting which you aren't required to do. You just need to provide 1cuft of vent per car. If it were me, I would pick a location to put the vent and build it to a size that a damper could later be put in its place. Have the opening for inspection then swap out for a closeable damper to use when you will be conditioning the space. I haven't heard of this sort of req any place else for residential garages, commercial spaces may require ventilation.

Good luck with this stuff!

Gotcha, was going off of 18-28-401.5.1.5 in regard to the horizontal runs, but didn't realize it only had to do with mechanical ventilation.

My architect and I were joking about just adding a few windows and leaving them open for inspection - technically would meet the definition of an RO.

You're paying an architect, what is the scope of their work?

I would expect whomever is designing my building (not just the aesthetics) to design a building that meets the code

Completely get it, but I'm just trying to be collaborative and explore options, given that this is a newer requirement that he hasn't run into yet. Hence I just figured I'd ask here, I've lurked on this forum for some time, but just wanted to see if anyone has dealt with a similar requirement.

 

[dscheidt]

Gotcha, was going off of 18-28-401.5.1.5 in regard to the horizontal runs, but didn't realize it only had to do with mechanical ventilation.

My architect and I were joking about just adding a few windows and leaving them open for inspection - technically would meet the definition of an RO.

It wouldn't, because there are other provisions requiring that openings be covered and protected from weather and vermin. But yeah, this is annoying.

you have a couple options, the simplest of which is a louvered vent on a side wall, or a roof vent, etc. The better (but more money) way of doing it is with an ERV, which you'd need to equip with some air quality sensors (monitoring CO2 as a code min, but you might well want CO and particulate for a garage). The ERV runs as required to keep the room CO2 below the threshold. There are ERVs with sensors built in, but most of them have dry contacts so they can be run by a remote sensor. You say conditioned by a heat pump. Do you mean a split system with a self contained head, or a system with ducts. If you're having ducts, the erv can be integrated into them (typically, exhausting return air, and supplying makeup air to be conditioned).

 

[danski0224]

I would suggest having a face to face with the HVAC inspector and ask him/her how to comply with the code.

It's been a while, but the 2012 Energy Code introduced some stuff for things like garages and sunrooms so they aren't tied into the regular HVAC system.

I suspect that this Chicago code requirement is in place to deter living space. Plenty of 2nd story "inlaw suites" that are part of detached garages in Oak Park for example.

 

[inphx]

In AZ the city was a stickler in requiring a slope on foundation plan in my toy barn which was minimized but not erased on plan by designating the area only immediate to the garage door as an imaginary parking area.

 

[Gurvy522]

It wouldn't, because there are other provisions requiring that openings be covered and protected from weather and vermin. But yeah, this is annoying.

you have a couple options, the simplest of which is a louvered vent on a side wall, or a roof vent, etc. The better (but more money) way of doing it is with an ERV, which you'd need to equip with some air quality sensors (monitoring CO2 as a code min, but you might well want CO and particulate for a garage). The ERV runs as required to keep the room CO2 below the threshold. There are ERVs with sensors built in, but most of them have dry contacts so they can be run by a remote sensor. You say conditioned by a heat pump. Do you mean a split system with a self contained head, or a system with ducts. If you're having ducts, the erv can be integrated into them (typically, exhausting return air, and supplying makeup air to be conditioned).

Mini-split with a wall-mounted head, non-ducted. I plan on using the space as a workshop, and wanted air conditioning in addition to heat. Since the garage is just shy of 1000sqft and one large open space, I felt a heat pump would be effective. We have solar on the house and tend to produce excess energy in the wintertime anyways, and I was eventually planning on installing batteries (for self-consumption) in the garage. Hence the heatpump vs an NG heater.

Was exploring ERVs, and just mechanical ventilation in general. The trouble is the code calls for static ventilation, but I'd imagine an inspector wouldn't necessarily ding us for adhering to more stringent code requirements, such as the 0.75 CFM intake / 1 CFM exhaust per SF requirement for garages that hold 6 cars +

Seems like the mechanical ventilation is not required to be on all of the time - only if CO levels exceed 50ppm. Has anyone used one of these sensors ? Would it just trigger off a relay or low-voltage switch?

 

[PCustoms]

Are you parking in this garage?

If not, then it's a shop.

 

[Gurvy522]

Are you parking in this garage?

If not, then it's a shop.

I do plan on storing cars in this garage, but not to it's maximum (3 car) capacity. Most of the time, I will only keep cars in the center bay, which will also have a 4-post lift.

Arguably, one of the spots will primarily for a camper (trailer), not a car.... but even if it we make it past permitting, I'd rather not roll the dice depending on the mood the inspector will be in.

Edit : Arguably, if I classified this building as a workshop, I don't think it would even make it past zoning here.

 

[dscheidt]

Are you parking in this garage?

If not, then it's a shop.

Which, ignoring the 'can't build a shop building in a residential zoned area' problem, would require a different set of ventilation requirements, which would require mechanical equipment to meet. And it's entirely different section of the energy code, so you'd have to meet those performance requirements, which are higher. You'd probably also trip over having to have indoor plumbing, too.

 

[75gmck25]

Make sure your architect understands the pitfalls of building a garage as conditioned space. If it's considered habitable space it may lead to requirements for an air leak test and other residential code requirements. It usually best to get it approved as just a well-insulated garage and allow for adding HVAC later on. Use the same process with electrical and don't get carried away with wiring for every possible piece of equipment.

 

[Gurvy522]

Make sure your architect understands the pitfalls of building a garage as conditioned space. If it's considered habitable space it may lead to requirements for an air leak test and other residential code requirements. It usually best to get it approved as just a well-insulated garage and allow for adding HVAC later on. Use the same process with electrical and don't get carried away with wiring for every possible piece of equipment.

Understood. Haven't gotten any pushback on the conditioned aspect of it, and the HVAC is included in the plans being sent in for permitting. When they kicked the plans back to us, they mentioned nothing of the electrical or HVAC, just strictly this new venting requirement.....

After further research, as far as the venting issue goes... it seems like we might be able to meet code by just adding a louver to the side door or overhead doors. Adding a louver to the garage doors seems a bit unattractive, so if we can swing it, I think we'll probably just do an adjustable louver on the side door, as long we can find a fire-rated assembly....

Verifying it now, but if anyone runs into a similar issue, this is what I think we'll use : https://www.activarcpg.com/wp-content/uploads/Louver-1900ASG-Submittal.pdf

 

[bamawildcat]

There are plenty of fart fans installed in garages to get rid of humidity or fumes. Fart fans also go into conditioned bathrooms. Install one of those, and they have built in dampers.

 

[dcg9381]

Here are the particulars. It reads to me that a 600 sqft garage would require a "relief opening" than can do 600 cfm at a vent rate of under 1000 cfm.

It doesn't say that you have to vent it, it just says you need a big enough hole not to cause air noise if you did vent it.

HRV/ERVs are common up north for conditioned space. But as a I read this a simple manual attic fan, through wall vent - sized appropriately meets code. But none of that is required, just an intake hole area big enough not to make a bunch of noise.

After further research, as far as the venting issue goes... it seems like we might be able to meet code by just adding a louver to the side door or overhead doors. Adding a louver to the garage doors seems a bit unattractive, so if we can swing it, I think we'll probably just do an adjustable louver on the side door, as long we can find a fire-rated assembly....

That's how I'd do it, or a "wall louver" and if I wanted, after the fact, close it up on the inside.


If you HVAC this space and tightly insulate it (probably not a factor with garage doors) your HVAC guy may have opinions on "fresh air intake".

 

[Gurvy522]

Here are the particulars. It reads to me that a 600 sqft garage would require a "relief opening" than can do 600 cfm at a vent rate of under 1000 cfm.

It doesn't say that you have to vent it, it just says you need a big enough hole not to cause air noise if you did vent it.

HRV/ERVs are common up north for conditioned space. But as a I read this a simple manual attic fan, through wall vent - sized appropriately meets code. But none of that is required, just an intake hole area big enough not to make a bunch of noise.





That's how I'd do it, or a "wall louver" and if I wanted, after the fact, close it up on the inside.


If you HVAC this space and tightly insulate it (probably not a factor with garage doors) your HVAC guy may have opinions on "fresh air intake".

You're correct - if we went with mechanical ventilation we're looking at 1cfm/sf - code points out that this does not have to run all of the time if you have a sensor/switch that turns on mech. ventilation if CO exceeds 50ppm. That's technically the "commercial" code requirement, but I'm sure would be accepted on a residential project. But all of that seems like time, money, and complexity... if we can get away with a louver, seems like a simpler option.

 

[dcg9381]

But all of that seems like time, money, and complexity... if we can get away with a louver, seems like a simpler option.

I get it 100%. But this is the fun part of designing it so it passes inspection. Your area is a little "tighter" than most. You're doing it right!

I'm way south of you so heat is an issue, I installed a simple "attic fan" that is triggered by over-temperature (heat soaked cars) - it vents out the perforated soffit, but unsure how you calculate that. Wasn't required by code, just a nice-to-have. Not sure I'd handle it in a "cold" area.

 

[u3b3rg33k]

You're correct - if we went with mechanical ventilation we're looking at 1cfm/sf - code points out that this does not have to run all of the time if you have a sensor/switch that turns on mech. ventilation if CO exceeds 50ppm. That's technically the "commercial" code requirement, but I'm sure would be accepted on a residential project. But all of that seems like time, money, and complexity... if we can get away with a louver, seems like a simpler option.

for the sake of argument, if you did an ERV on an off-the-shelf CO2 sensor, it'll trip on max speed if you had a car running with the door shut real fast. CO monitoring may be a requirement for commercial garages, but an engine would make more CO2 than CO anyways, so you'd get the same result (engine on, fan on).

set for something like 600PPM CO2 and it'd only run when occupied/something was making CO2.