Cold Concrete Garage Floor? Here’s How to Insulate & Heat
Trying to warm up a concrete garage can feel like trying to warm up a black hole. Whatever heat you throw at it just gets sucked away.
In this guide, we’ll explore how to make a concrete garage warm during a cold winter.
In short, the way to heat up a concrete garage is through smart insulation. Insulation the walls, door, and ceiling are the most important (heat rises). Covering a concrete garage floor with a more thermally conductive material (epoxy/rubber/carpet) can also help greatly.
We’ll explore this further below, as well as:
- Why concrete is so tough to warm up
- The best thought process for garage insulation
- Focusing warmth into one area
- Moisture considerations when covering concrete
- The best type of heater for a concrete garage
Ready? Then let’s dive in!
Back when I was a Civil Engineering student, I couldn’t believe how much we had to learn about concrete.
We had entire modules – just on concrete!
It’s such a prevalent building material. And there’s many characteristics that are important to understand.
One of them is it’s thermal conductivity.
Thermal conductivity might sound tricky, but it’s just the rate at which the material takes on heat. For example, steel has a high thermal conductivity. If you put a piece of wool in the oven for 5 minutes, it would sear your hand if you were to touch it! It takes on heat super quickly.
In scientific terms, wool has a thermal conductivity of around 0.7W/(mK).
(I won’t go too much into explaining the units – explanation here)
On the other hand, concrete has a thermal conductivity of around 0.6.
If you put concrete in a hot oven for 5 minutes, it’ll probably still be quite cool when you take it out. It takes a much longer time to heat up.
What Does This Have to Do With My Garage?
All you need to understand is that concrete takes a long time to absorb heat.
That’s why it’s such a difficult material to work with.
On a winter morning, a concrete floor has slowly dropped down to freezing cold temperatures. And you need a TON of warmth (and time) to bring it’s temperature back up again.
That’s why it’s so hard to heat a concrete garage.
Side note: concrete is also used because of it’s heat properties. Some modern concrete buildings are are built around heating efficiency. The concrete is warmed early in the day (through heating or sunlight). Then, since it holds a temperature for so long, it keeps the whole building warm until late in the evening.
The Best Thought Process for Insulating a Garage
When it comes to keeping a room warm, insulation is the key.
I won’t dive into too much detail here. (Though I have done in other posts like this one).
Basically, if you want your room to be warm, you must insulate it.
Otherwise the only thing your heater is burning are your dollars.
With that said, let’s walk through a general thought process for insulating a garage:
- Heat rises. Make sure your ceiling is insulated or your heat will quickly disappear.
- Make sure to include a vapor barrier between the warm area and the insulation. You don’t want moisture trapped in there.
- If you’re going to use propane to power a heater, makes sure you have some ventilation. Simple roof vents work great.
- Insulate your walls. After trying for the ceiling the heat will next try to escape out the walls. Standard wall insulation is R12 for 2×4 walls or R20 for 2×6.
- Vapor barrier again. Seal all gaps. Moisture will = damp air and mold.
- Now for the Garage door.
- Consider super lightweight insulation (ie bubble wrap style sheets).
- If desperate you could use heavier, but your door may not open!
- Seal edges with gaskets.
- And lastly, the floor.
- One of least important but can be hard to deal with if it’s straight concrete.
- Simplest solution is to lay down rubber mats, carpet, or similar materials. Condensation can occur on the coldest surface, so rubber mats with dimples can help with grip. (If you’re going to use it as a gym)
Why is the Concrete Floor the Last Priority?
I know what you may be thinking –
“who cares about insulating the ceiling, my floor is ice-cold!!”
Although your floor is cold, we first need to make sure the room is going to stay warm.
Here’s a good visualization – below is the heat flow from a standard space heater. If we don’t insulate the surfaces that heat is going to, then it’s going to fade away.
Making the floor warm isn’t the first priority. Making the room warm is.
Concrete vs Moisture
Back to engineering classes again.
This time, class, we’re learning about concrete and it’s mortal enemy – water.
While concrete looks solid, it’s actually full of microscopic holes. Moisture can pass through these material, risking mold or damage to the inside of your space.
(It can also damage the concrete. Water in the holes, if frozen in winter, will expand and put a lot of internal pressure on the concrete. Causing cracking.)
Putting down a simple water/vapor barrier between the concrete and any interior layers should always be done.
Best Material to Insulate Concrete Garage Floors
We know that concrete takes forever to warm up – so what’s the best way to deal with it?
Cover it with something that is quick to warm up!
Your garage floor itself just needs around an inch of material which will take on warmth (reasonably) quickly.
Some common options are:
- Epoxy finishes. Great for durability and to still drive over.
- Rubber tiles. Super quick to install, cheap, and can handle car weight.
- Vinyl flooring. Another easy option, available in cheap roll-out styles. Can be hard to patch-repair, unlike tiled rubber.
- Carpet. Not just any carpet, but ones made for the garage.
Separate Out A Smaller Area
If you’re only going to need a small area of the garage (for a workstation, gym, or workbench) – consider separating it out until it’s own smaller area.
By putting up a few stud walls, some insulation, and laying down a carpet you’ll create a much smaller space which is super easy to keep warm. Especially when combined with a space heater.
Using the space to work out?
Make sure you always start with plenty of layers on. You’ll soon warm up when working out, and can strip back on layers as your body heats up.
What Type Of Heater For A Concrete Garage?
Trying to warm up a large, cold, hard space is no easy feat.
That’s why choosing the right type of heater is so important.
We’ve done a ton of articles on this subject – so I’ll just give you a quick run-down here.
If you’d like more detail, check out these posts:
- Cheapest Electric Heaters to Run
- Are Propane Heaters Safe? Can You Use Them Indoors?
- Most Efficient Heaters for Small Rooms
Best Heaters for a Concrete Garage
- Propane Torpedo. Provided the garage has some airflow (roof vents or openings around the garage door) then a propane heater may be your best option. Torpedo heaters in particular are SUPER powerful, and can direct their strong heat to the area you’re working in.
- Propane Radiant. As above, but these radiant heaters radiate their heat outwards. These are better for small-medium sizes garages – they’re powerful enough to heat the whole space. Not just a small area.
- Oil-Filled Electric. If you need to go with an electric heater, than an oil-filled model is best. These take longer to warm up, but hold the heat for an extremely long time. The best bang for your buck in terms of energy used to heat provided.
- Infrared Heaters. One of my favorite options for a garage are infrared heaters. These are also super efficient, and their heat holds well even if the garage isn’t so well insulated. By heating up objects (like the sun does) instead of the air, they are fantastic for directing warmth towards a smaller working area.
There’s nothing worse than being shut out from your own garage due to the winter cold.
I hope this quick guide has helped give you some ideas about how to fight back.
As always, the bottom line is to insulate as much as you can. And, of course, to get a good heater.
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Have a great day!