Should I Insulate My Garage Ceiling?

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Jul 19th, 2021 4:23 pm

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Jul 13th, 2021 11:16 pm

Jagstyles [OP]: Deal Addict; Aug 7, 2013; 1625 posts; 524 upvotes; GTA

Jul 13th, 2021 11:16 pm

Should I Insulate My Garage Ceiling?

I’m going to be remodeling my garage. The garage is attached to my home but it’s a separate space with no bedrooms above the garage. Currently, it’s completely open to the rafters and I can see the roof plywood and it has two existing vents. Not sure why they vented it since it’s not insulated and has no HVAC going into the garage.

As part of the remodeling, I’m dropping the ceiling and closing it off with a nice loft area for storage. My question is whether I should insulate the ceiling in the garage? I’m also having the entire roof of my home done and what I do with the garage will determine if I keep the two vents when redoing my roof as well.

Would insulating the garage ceiling make it cooler in the summer and warmer in the winter? I’ve noticed my garage is like an oven in the summer, more so that my precious home.

Any feedback would be appreciated.

23 replies

Jul 13th, 2021 11:51 pm

SubjectivelyObjective: Deal Addict; Jun 26, 2019; 2034 posts; 1772 upvotes; GTA

Jul 13th, 2021 11:51 pm

Jagstyles wrote: ↑ Would insulating the garage ceiling make it cooler in the summer and warmer in the winter? I’ve noticed my garage is like an oven in the summer, more so that my precious home.

The long story short of it is yes, it will. If the whole garage is insulated it will absorb or transfer heat to the house at a faster rate before relative to the exterior walls. So you will get leech a bit of cool in the summer and heat in the winter off your house so it will be better than the outdoors.

If you don't have a insulated garage door and the whole place is not air sealed, I would say the insulation is basically worthless. Air leakage and thermal bridging will be way worse than losses through insulation. An insulated garage door will likely keep you garage above freezing all winter.

Also, unless you plan on heating the garage or cooling the garage to use it as a functional space for a workshop or working out in the winter, then I don't think insulation is worth the effort imo.

Jul 14th, 2021 1:07 am

Jerico: Deal Guru; Jan 25, 2007; 12418 posts; 7592 upvotes; Paris

Jul 14th, 2021 1:07 am

SubjectivelyObjective wrote: ↑ Also, unless you plan on heating the garage or cooling the garage to use it as a functional space for a workshop or working out in the winter, then I don't think insulation is worth the effort imo.

For once I disagree. My parents had their garage builder insulated (walls, door and ceiling) and just the heat of the vehicle in and out would keep it above freezing all winter.

If OP is doing some work, the extra $200 to insulated the garage ceiling is well worth it for future.

+3

Jul 14th, 2021 1:40 am

IcarusLSC: Deal Addict; Nov 7, 2016; 2655 posts; 1591 upvotes; Ontario

Jul 14th, 2021 1:40 am

If your closing in the ceiling with drywall you will defiantly want the roof vented at the soffit and top...

Jul 14th, 2021 1:53 am

Quentin5: Deal Expert; Feb 8, 2014; 28905 posts; 12564 upvotes; Socially Distanced

Jul 14th, 2021 1:53 am

Yes insulate it. It will help a great deal in summer and a bit in winter.

Since the garage door is a crummy insulator, the garage walls are likely not insulated and your garage is not conditioned it won't stay as cool as the house in summer or as warm in winter, but insulation will moderate temperatures noticeably and as mentioned earlier reduce some indirect costs to your house heating and cooling bills.

In fact in Rand McNally they wear hats on their feet and hamburgers eat people

+2

Jul 14th, 2021 8:49 am

The Canterbury Tail: Deal Addict; Jan 10, 2009; 1676 posts; 1058 upvotes; Toronto

Jul 14th, 2021 8:49 am

Oh and they vented the garage because running an internal combustion engine in an enclosed space tends to give off dangerous fumes and you really need them vented out one way or another.

Jul 14th, 2021 9:04 am

Jagstyles [OP]: Deal Addict; Aug 7, 2013; 1625 posts; 524 upvotes; GTA

Jul 14th, 2021 9:04 am

IcarusLSC wrote: ↑ If your closing in the ceiling with drywall you will defiantly want the roof vented at the soffit and top...

Would two vents through the roof of the garage not be sufficient? You mention venting through the soffits?

Jul 14th, 2021 9:28 am

Jon Lai: Deal Expert; May 30, 2005; 48262 posts; 9155 upvotes; Richmond Hill

Jul 14th, 2021 9:28 am

The Canterbury Tail wrote: ↑ Oh and they vented the garage because running an internal combustion engine in an enclosed space tends to give off dangerous fumes and you really need them vented out one way or another.

I mean, you're not supposed to be running an engine with the doors closed...

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+1

Jul 14th, 2021 9:31 am

Jon Lai: Deal Expert; May 30, 2005; 48262 posts; 9155 upvotes; Richmond Hill

Jul 14th, 2021 9:31 am

Kind of off topic, but what am I looking at in terms of cost to have my garage fully insulated, for an attached garage on 2 sides (back and side) and room above the garage, double doors? And what is the feasibility of running heating/cooling in the garage other than to run portable heaters or A/C? The house will be powered by geothermal so ideally I'd love to tap into the central system since it would be "free" but I understand that's against code.

Tons of things for sale!
Silver Coins and Numismatics | Hardwood cutting boards, dining tables, home decor, and more | Heatware

Jul 14th, 2021 10:03 am

IcarusLSC: Deal Addict; Nov 7, 2016; 2655 posts; 1591 upvotes; Ontario

Jul 14th, 2021 10:03 am

Jagstyles wrote: ↑ Would two vents through the roof of the garage not be sufficient? You mention venting through the soffits?

It depends on the type of vents and square footage of the roof. Lots of calculators online for figuring it out once you do some measuring.
Air is usually drawn in through the soffits and out the roof vents.

Jul 14th, 2021 10:47 am

Quentin5: Deal Expert; Feb 8, 2014; 28905 posts; 12564 upvotes; Socially Distanced

Jul 14th, 2021 10:47 am

Jon Lai wrote: ↑ Kind of off topic, but what am I looking at in terms of cost to have my garage fully insulated, for an attached garage on 2 sides (back and side) and room above the garage, double doors? And what is the feasibility of running heating/cooling in the garage other than to run portable heaters or A/C? The house will be powered by geothermal so ideally I'd love to tap into the central system since it would be "free" but I understand that's against code.

Its most certainly not free. The energy to run the pumps and accoutrements can make it less energy efficient than an air source heat pump.
That said its a fools errand to heat and cool your garage unless your made of money. I would accept the moderation done by insulation.

In fact in Rand McNally they wear hats on their feet and hamburgers eat people

+1

Jul 14th, 2021 11:04 am

The Canterbury Tail: Deal Addict; Jan 10, 2009; 1676 posts; 1058 upvotes; Toronto

Jul 14th, 2021 11:04 am

Jon Lai wrote: ↑ I mean, you're not supposed to be running an engine with the doors closed...

But what you do run when you drive in and out won't be fully cleared just by the doors opening and closing. Mostly but not fully. And how many people run the car to warm it up before they open the garage door and drive out?

Jul 14th, 2021 11:09 am

BDSL: Deal Addict; Sep 22, 2009; 3273 posts; 2154 upvotes; Markham

Jul 14th, 2021 11:09 am

Adding just the ceiling insulation will help a little. But how far do you want to go ( (i.e. insulating the ceiling, ceiling hatch, the garage doors, the garage walls)?
Another question is...how often do you spend time in the garage that you need it to be partially or fully insulated?
Most people here just park the vehicles in there and use it for storage.

Jul 14th, 2021 11:10 am

rilles: Deal Fanatic; Aug 29, 2001; 6228 posts; 1478 upvotes; rural ontario

Jul 14th, 2021 11:10 am

No (unless you plan to live/work in there). I fully insulated my last house garage including the door. Other then cash out the door, I'm not sure what I gained. But summer was way hotter, winter was wet mess in the garage.
Next house did not have an insulated garage (no rooms above it) and I like it much better.. summer is much cooler and winter is snow blobs I can shovel away.

72 69 6c 6c 65 73

Jul 14th, 2021 11:11 am

BDSL: Deal Addict; Sep 22, 2009; 3273 posts; 2154 upvotes; Markham

Jul 14th, 2021 11:11 am

The Canterbury Tail wrote: ↑ But what you do run when you drive in and out won't be fully cleared just by the doors opening and closing. Mostly but not fully. And how many people run the car to warm it up before they open the garage door and drive out?

You are not suppose to leave the vehicle running inside the garage with the doors closed.
And it is never a 100% seal between the garage and the home interior.

Jul 14th, 2021 11:51 am

Jon Lai: Deal Expert; May 30, 2005; 48262 posts; 9155 upvotes; Richmond Hill

Jul 14th, 2021 11:51 am

Quentin5 wrote: ↑ Its most certainly not free. The energy to run the pumps and accoutrements can make it less energy efficient than an air source heat pump.
That said its a fools errand to heat and cool your garage unless your made of money. I would accept the moderation done by insulation.

Fair enough. I plan on using my garage as a workshop so even moderation of +/- 10C would be fine with me.

What would be the cost and how much real estate will I be losing on the exterior walls/door?

Tons of things for sale!
Silver Coins and Numismatics | Hardwood cutting boards, dining tables, home decor, and more | Heatware

Jul 14th, 2021 12:15 pm

Jagstyles [OP]: Deal Addict; Aug 7, 2013; 1625 posts; 524 upvotes; GTA

Jul 14th, 2021 12:15 pm

rilles wrote: ↑ No (unless you plan to live/work in there). I fully insulated my last house garage including the door. Other then cash out the door, I'm not sure what I gained. But summer was way hotter, winter was wet mess in the garage.
Next house did not have an insulated garage (no rooms above it) and I like it much better.. summer is much cooler and winter is snow blobs I can shovel away.

Are you saying that insulating the garage ceiling in your previous home resulted in an even hotter garage in the summer and why was it wet in the winter? I would expect with proper roof vents that the opposite should occur.

Jul 14th, 2021 12:36 pm

ChubChub: Deal Addict; Oct 9, 2010; 3138 posts; 1321 upvotes; Windsor

Jul 14th, 2021 12:36 pm

The Canterbury Tail wrote: ↑ But what you do run when you drive in and out won't be fully cleared just by the doors opening and closing. Mostly but not fully. And how many people run the car to warm it up before they open the garage door and drive out?

Very few people do this. And those that do, it's a situation that slowly solves itself.

One who is offended by truth, has no place among those who seek wisdom.

+2

Jul 14th, 2021 1:22 pm

rilles: Deal Fanatic; Aug 29, 2001; 6228 posts; 1478 upvotes; rural ontario

Jul 14th, 2021 1:22 pm

Jagstyles wrote: ↑ Are you saying that insulating the garage ceiling in your previous home resulted in an even hotter garage in the summer and why was it wet in the winter? I would expect with proper roof vents that the opposite should occur.

The last house had a room above it. No ventilation from above. Winter it retained so much heat it melted the snow on the vehicles vs now the space is colder. A nitpick but I didn't see any value in the insulation.

72 69 6c 6c 65 73

Jul 14th, 2021 3:02 pm

Quentin5: Deal Expert; Feb 8, 2014; 28905 posts; 12564 upvotes; Socially Distanced

Jul 14th, 2021 3:02 pm

Jon Lai wrote: ↑ Fair enough. I plan on using my garage as a workshop so even moderation of +/- 10C would be fine with me.

What would be the cost and how much real estate will I be losing on the exterior walls/door?

Insulating the roof correctly should give you moderation in summer and some in winter.
Insulating the walls should help a bit as well. I would suggest dense pack cellulose if the stud bays are empty. It won't address thermal bridging (loss through the studs) but should be low cost and decent.
But you still have the garage door and the floor. Insulating the floor is impractical and the door is tricky, Many insulated garage doors claim fake numbers and/or have lots of thermal bridging through the metal components. And are not close to airtight.

As for cost for all this there is no number i can give you becasue every garage is different. You need to get quotes.

In fact in Rand McNally they wear hats on their feet and hamburgers eat people

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