Home & Garden

Garage ventilation

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  • Aug 28th, 2021 8:19 pm
[OP]
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May 30, 2016
71 posts
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Garage ventilation

Hi,

I would like to ventilate my garage. The door is exposed to the sun most of the time, and the garage's temperature can reach 35 Celcius when the outdoor temp is 30C.

I am thinking of installing an exhaust fan on the top of the sidewall close to the garage door. Since the door is constantly closed and the walls and ceiling insulated, I guess I also need an intake that would be installed at the bottom of the other end of the same wall. The good thing is that the intake will pull the fresh air from the side of the house which is never exposed to the sun.

Since there is a wind tunnel between my and neighbor's house, do I need to install an exhaust fan or a simple vent would do the job?

How big need to be the vent and air intake ducts?

Any advice?
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33 replies
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Mar 4, 2007
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Hi,

Why do you want to ventilate your garage? How cold do you want the garage to be when it's 30*C outside? You realize that with simple ventilation, the coolest the inside of your garage is ever going to get is the same temperature outside.
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Feb 8, 2014
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Its not a terrible idea, lowering the garage temperature will lower the house temperature/AC load a bit as there is one less hot wall. Or at least less hot.

That said passive vents probably won't do the job the temperature differential is not huge. If you kept the garage door open all night that would cool it down. And expose all your tools and stored items to anyone with sticky fingers.

Active cooling may not be worth the savings.
Also the garage door is not very airtight, fixing that is not easy, its a contraption with lots of moving pieces. Insulated garage doors are not that insulated becasue the edges and metal is not good at insulating. But that might be your best bet because at least the radiated heat will be reduced. But will that ever pay for itself, i am skeptical. But i have not run any numbers.

Perhaps the best idea is just to keep the garage door open for a couple hours after the sun sets, a cheap solution and just move your loose items elsewhere?

Are the walls/ceiling between the garage and house well insulated?
In fact in Rand McNally they wear hats on their feet and hamburgers eat people
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Sep 22, 2009
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Markham
Superbobby wrote: Hi,

I would like to ventilate my garage. The door is exposed to the sun most of the time, and the garage's temperature can reach 35 Celcius when the outdoor temp is 30C.

I am thinking of installing an exhaust fan on the top of the sidewall close to the garage door. Since the door is constantly closed and the walls and ceiling insulated, I guess I also need an intake that would be installed at the bottom of the other end of the same wall. The good thing is that the intake will pull the fresh air from the side of the house which is never exposed to the sun.

Since there is a wind tunnel between my and neighbor's house, do I need to install an exhaust fan or a simple vent would do the job?

How big need to be the vent and air intake ducts?

Any advice?

Untitled.png
IMG_2914_2.jpg
You will need to knock out 2 holes on the side (brick wall). Then install 2 fans (that you can get from Princess Auto). Then do the electrical.
All this just to lower the garage temperature for a few degC.

Do you work inside your garage often?

When I work in the garage during hot days, I open the garage doors and the rear door. Turn on the portable fan. I work on cars and welding. It will be warm but I am only in the garage once a month and only for a few hours.
[OP]
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May 30, 2016
71 posts
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Quentin5 wrote: Insulated garage doors are not that insulated becasue the edges and metal is not good at insulating. But that might be your best bet because at least the radiated heat will be reduced. But will that ever pay for itself, i am skeptical. But i have not run any numbers.
I am skeptical too. Not counting that I would have to remove the insulation in winter. I like to keep my cars in the garage and want to slow down the process of rust by keeping a low temp ;) Another reason why I want to ventilate it.
Quentin5 wrote: Perhaps the best idea is just to keep the garage door open for a couple hours after the sun sets, a cheap solution and just move your loose items elsewhere?
I wish I could just do that :) but I forgot to mention that I occasionally spend some time detailing or doing some maintenance on my cars. The neighbor is often with his family in his garage or in front of his house. Our houses are 4 FT apart so I am in need of privacy and don't want to disrupt their peace when using power tools.
Quentin5 wrote: Are the walls/ceiling between the garage and house well insulated?
They are but there is some limitation as you probably know. Since there is no ventilation, heat is probably finding its way to the second floor and through the walls.

Homedepot could not give me any advice on this. The reason why I am here. I am afraid of ending up with some useless holes in the wall and an angry wife ;) I will keep looking for some solutions. Thanks for your reply!
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Nov 28, 2016
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Ive thought about this the last 15 years in my two houses now. And for the few weeks a year its like this, I just live with it and decided, its a garage, I dont live in there.

Its the cost to do this versus the outcome, and then basically in the winter, have two holes to worry about when its -35 in a heated garage, I found the best way to handle the heat are the following

1. Increase your attic insulation, usually garage insulation is done poorly compared to the rest of the house
2. Install a big ceiling fan. At least it moves the air around when you are in there, making it feel cooler. I did that this winter for the first time and it definitely helped this summer
3. Don't park in the garage when you get home. The heat from the motor and the metal will increase the heat in the garage
4. If all else fails and you are home, open the garage doors 1/4 of the way, and then your entrance door. At least you can get a cross breeze going.
5. Cool the garage off at night if you can with a side entrance door open. Realize this all depends on the door location and your neighborhood But the cooler you can get the garage, the longer it will take to heat up
6. Minimize the amount you open any door to the outside.
7. Have a window, make sure you have a blind to block the sun

I had the garage many times this summer at 35 or 36 degrees. But that was when it was +39 outside as well. On days that we were on vacation and no one was home with thsoe temps, the garage was mid 20's all day because no heat was being let in with the usual activity (I have an Ecobee sensor in my garage so I can check temps)

We have always had a fridge or a freezer, or both in our garages the last 15 years, and I was always worried the increased heat would cause issues for them. Im sure they had to run more, but Ive never had an appliance crap out on me yet
[OP]
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May 30, 2016
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BDSL wrote: You will need to knock out 2 holes on the side (brick wall). Then install 2 fans (that you can get from Princess Auto). Then do the electrical.
All this just to lower the garage temperature for a few degC.

Do you work inside your garage often?

When I work in the garage during hot days, I open the garage doors and the rear door. Turn on the portable fan. I work on cars and welding. It will be warm but I am only in the garage once a month and only for a few hours.
No brick, just siding ;) The electrical part is what I am worried about the most. According to the building code, it seems that I am not allowed to connect anything to the ceiling outlet used by the garage door opener. So I might have to install a junction box and run a new cord.

I occasionally do detailing and maintenance on my cars. The rear door gives access to the house ;(
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Nov 28, 2016
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Superbobby wrote: No brick, just siding ;) The electrical part is what I am worried about the most. According to the building code, it seems that I am not allowed to connect anything to the ceiling outlet used by the garage door opener. So I might have to install a junction box and run a new cord.

I occasionally do detailing and maintenance on my cars. The rear door gives access to the house ;(
So the only entrance door you have to the garage is from the inside house?

I thought all attached garages had to have 2 entrance doors, one to the house, and then one to the outside.
Last edited by WikkiWikki on Aug 25th, 2021 10:59 am, edited 1 time in total.
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Oct 2, 2018
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I don't think adding a vent or two is going to assist you much if at all, you may get a couple of degree's cooler however not getting below ambient temp so on a scorching day you'll still be scorching hot.

I have a work bench in my garage and a work out area, a large industrial fan circulates air more so that a vent fan and again makes it bearable but temp wise not too much better. I also leave a window cracked open 6 inches (rear of garage in backyard space), again don't know if it really makes a big difference.

On super hot days it is just that, super hot. Only you can decide if the juice is worth the squeeze, but for the cost and having to make holes in the wall and run electrical you would also need really big fans to get the circulation you desire. I would be tempted to just go with an industrial sized fan to move the air, might accomplish the same goal without making holes in the walls.
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Sep 22, 2009
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Superbobby wrote: No brick, just siding ;) The electrical part is what I am worried about the most. According to the building code, it seems that I am not allowed to connect anything to the ceiling outlet used by the garage door opener. So I might have to install a junction box and run a new cord.

I occasionally do detailing and maintenance on my cars. The rear door gives access to the house ;(
Since you are only occasionally doing detailing/maintenance on your vehicles, I would try a big portable fan from Princess Auto or any big box store.
It is only hot in Canada for a few months. And you are probably only in the garage once every few weeks and only for a few hours.
A $20-50 fan can potentially solve your problem.
[OP]
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May 30, 2016
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WikkiWikki wrote: So the only entrance door you have to the garage is from the inside house?

I thought all attached garages had to have 2 entrance doors, one to the house, and then one to the outside.
Unfortunately, I have only one entrance door and it is for the inside house ;( There is only 4FT between the houses so I doubt a side door will be legal.
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Superbobby wrote: Unfortunately, I have only one entrance door and it is for the inside house ;( There is only 4FT between the houses so I doubt a side door will be legal.
I thought for code you needed to doors. But then again Im not a builder.

Why would the 4 feet matter? The door can be an inward swing.

Maybe look into that, if you were planning on cutting holes. See how much a door would be to install. or check to see if its allowed
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Superbobby wrote: Hi,

I would like to ventilate my garage. The door is exposed to the sun most of the time, and the garage's temperature can reach 35 Celcius when the outdoor temp is 30C.

I am thinking of installing an exhaust fan on the top of the sidewall close to the garage door. Since the door is constantly closed and the walls and ceiling insulated, I guess I also need an intake that would be installed at the bottom of the other end of the same wall. The good thing is that the intake will pull the fresh air from the side of the house which is never exposed to the sun.

Since there is a wind tunnel between my and neighbor's house, do I need to install an exhaust fan or a simple vent would do the job?

How big need to be the vent and air intake ducts?

Any advice?
Is your garage door insulated? I'm in a similar situation to you and with my insulated garage door and garage walls, my garage is only a couple degrees warmer (25C) than the house, despite the outer surface being almost too hot to touch.
WikkiWikki wrote: I thought for code you needed to doors. But then again Im not a builder.

Why would the 4 feet matter? The door can be an inward swing.

Maybe look into that, if you were planning on cutting holes. See how much a door would be to install. or check to see if its allowed
My 1979 built in garage only has one pedestrian door.
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engineered wrote: Is your garage door insulated? I'm in a similar situation to you and with my insulated garage door and garage walls, my garage is only a couple degrees warmer (25C) than the house, despite the outer surface being almost too hot to touch.


My 1979 built in garage only has one pedestrian door.
Im probably wrong then, or maybe thats changed over time and new builds have two doors for attached garages and code has changed.
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WikkiWikki wrote: Im probably wrong then, or maybe thats changed over time and new builds have two doors for attached garages and code has changed.
Building codes also vary from location to location. But in my last home with an attached garage in the Edmonton area, there was only a single door into the dwelling, and then the big vehicle door. And it was built in the 90's, I believe.

C
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CNeufeld wrote: Building codes also vary from location to location. But in my last home with an attached garage in the Edmonton area, there was only a single door into the dwelling, and then the big vehicle door. And it was built in the 90's, I believe.

C
Or cost, extra door costs more. My previous house had to outside doors, front and back and then the one in the house. Probably design of the house, garage, location, etc, etc all have the reasons why
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Buy some rigid foam insulation, cut to size and insulate the door yourself.
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Superbobby wrote:
I am skeptical too. Not counting that I would have to remove the insulation in winter. I like to keep my cars in the garage and want to slow down the process of rust by keeping a low temp ;) Another reason why I want to ventilate it.
It will still stay cold in winter, the floor is not insulated.


I wish I could just do that :) but I forgot to mention that I occasionally spend some time detailing or doing some maintenance on my cars. The neighbor is often with his family in his garage or in front of his house. Our houses are 4 FT apart so I am in need of privacy and don't want to disrupt their peace when using power tools.
Makes sense. However if you punch some holes in the walls sound will go through them very easily. Fans in the holes will not help much. Brick is good at dulling sound, Metal is not. Plastic is in between. Ditto for foam.


They are but there is some limitation as you probably know. Since there is no ventilation, heat is probably finding its way to the second floor and through the walls.
Heat travel through studs is known as thermal bridging. Often hard to mitigate. But cooling the garage a few degrees will make only a small difference here.
If the stud bays between the garage and house are empty then you can fill them with blown in cellulose for low cost. This will keep heat out of the house. It will actually make the garage a bit hotter but the point will be that your HVAC is using less power. Similar to insulating your attic or exterior walls, the outside will actually get hotter but there you don't care becasue its the inside you care about.

Homedepot could not give me any advice on this. The reason why I am here. I am afraid of ending up with some useless holes in the wall and an angry wife ;) I will keep looking for some solutions. Thanks for your reply!
This is informally known as leaning on the counter advice.
Unless you want to spend more than you will save i suggest just leaving the garage door open for an hour or two in the evenings. Don't do anything noisy that might annoy the neighbours but don't leave your loose items unattended. Perhaps the kids can play basketball in the driveway or something?

Edit: Perhaps the best advice is to rotate your entire house, so the garage is pointing north. Hence no direct sun will fall on the uninsulated garage door Smiling Face With Open Mouth And Smiling Eyes

Very cost ineffective Winking Face
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Dec 31, 2007
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Superbobby wrote: I am skeptical too. Not counting that I would have to remove the insulation in winter. I like to keep my cars in the garage and want to slow down the process of rust by keeping a low temp ;) Another reason why I want to ventilate it.



I wish I could just do that :) but I forgot to mention that I occasionally spend some time detailing or doing some maintenance on my cars. The neighbor is often with his family in his garage or in front of his house. Our houses are 4 FT apart so I am in need of privacy and don't want to disrupt their peace when using power tools.



They are but there is some limitation as you probably know. Since there is no ventilation, heat is probably finding its way to the second floor and through the walls.

Homedepot could not give me any advice on this. The reason why I am here. I am afraid of ending up with some useless holes in the wall and an angry wife ;) I will keep looking for some solutions. Thanks for your reply!
If you want to have privacy, limit noise pollution, and have ventilation, have you considered/tried opening up the door just a few feet? It would allow air flow and allow you to add a fan, give some privacy, reduce some noise.
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