Garage Insulation: A Comprehensive Guide

*We may earn a commission for purchases made using our links. Please see our disclosure to learn more.

Garage Insulation is perhaps the most important thing you can do to your garage in the winter months. Not only will it keep the room warmer, but it will save you money on heating bills and is therefore well worth the investment of time and money to do so.

The actual insulation itself can be done without the need for a specialist. Therefore, if you’re looking to learn more about how it’s done, or you’re just eager to learn more, you’ve come to the right place.

Why You should Insulate your Garage

Apart from the aforementioned savings on your heating bills, there’s actually more to it than that. A lack of insulation, or insulation done wrong can result in a cold, damp room and may even cause mould if you’re unlucky which may cause damage to your health in the long run.

Also, insulating your garage is a job that will only take you 1-2 days depending on the size of your garage but will last you years and will help you survive the winter months. This will mean you can do whatever you do in your garage without the unpleasant winter chill making you cold, it will also help to regulate the temperature of your garage all year round.

Finally, insulating your garage takes DIY knowledge that a beginner should know. Therefore, if you’re not confident with your ability to be a handyman/woman, you should still be able to do this yourself.

Types of Garage Insulation

First of all, let’s get familiar with the term R-value. The R-value basically measures how well a room is insulated with a higher R-value being better.

So, each type of garage insulation I’ll talk about will have varying R-value levels and varying amounts of effort to put in place. It’s therefore up to you on which method you choose.

Rigid Foam Insulation

Rigid foam will often come in materials similar to Styrofoam and comes in sheets with various sizes. Rigid foam insulation will offer your garage a high R-value per inch of thickness and can be cut to fit almost any space. This therefore makes a good choice for thin walls and for insulating garage doors.

If you want to insulate garage floor, one option is to use rigid foam covered in plywood or other subfloor material.

It is worth noting however, that you should check the fire rating on the rigid foam. Some types of rigid foam are not fire resistant and are therefore not suitable for garages with exposed applications.

Fibreglass Insulation

This type of insulation is the most commonly used in garages. It is usually sold in long blankets that will fit between your wall studs and your ceiling joists. If you’re looking to insulate the ceiling or roof better, you can always buy loose-fill fibreglass.

However, loose fibreglass has a low R-value, meaning you’ll usually have to install a minimum thickness of around 3 inches to properly insulate your garage.

Apart from that, it is easy to install, made from fireproof material, cheap and recyclable. Due to its compressibility, it is also perfect for sealing uneven surfaces. This makes it a good option for your garage if you can fit the few inches of fibreglass along each wall/ceiling.

Spray Foam Insulation

Spray foam is another strong option as it has a great R-value and is great for air-sealing. Usually used for warehouses or commercial garages, it may be slightly overkill for your garage, but a great option, nonetheless.

This is the case as it usually involves using high-end material which is mainly used for energy-efficient construction. I’d recommend this type if you’re converting your garage into a proper living space or maybe a workshop/gym that you use every day.

Cellulose Insulation

This type of insulation wasn’t commonly used until recently but is growing in popularity. This type of insulation is only really suitable for finished garages that need insulation.

Make sure you stack up on old newspapers or just buy a load (they’re really cheap) as you’ll need them. This is because cellulose insulation is made mainly from recycled newspapers and treated with a fire retardant.

You’ll also need a blowing machine (I’d suggest just renting one if you don’t own one). This is because the cellulose is blown into the wall and ceiling cavities, also aerates the cellulose and fluffs it up.

You’ll want to install cellulose by cutting holes in the wall material, filling the cavities between the frames, and then patching the holes. Cellulose insulation will offer your garage a good R-value while being fairly easy to install, definitely a good option if your garage is already built but in need of insulation.

Now we’ve had a look at the different types of insulation for your garage, let’s have a quick look at the costs.

Costs of Insulating your Garage

The cost of insulating your garage depends on the size of your garage and the type of insulation you use. Insulation doesn’t cost a fortune with most estimates putting it at 50 cents to $1.25 per square foot.

This means that the cost of insulating a two-car garage will cost you anywhere from $338-$845. Other factors come into play as well, such as if you have certain materials in your toolbox needed for the job.

I spoke about the materials needed for the job in my garage conversion article, but I’ll repeat it here for your convenience:

• Expanding foam
• Drywall
• Gloves and sleeves
• Fibreglass insulation
• Garage door insulation kit

This should have you sorted for most types of commonly used insulation methods. It is hard to give a more exact estimate as prices will vary massively depending on where you live. I’d suggest looking at Amazon for the best prices, I’ll also have an article on the best garage door insulation kits up soon so you can pick the perfect one for your garage.

One tip I’d use for insulating your garage is being consistent with the type you’re using for each area. For example, if you’re using fibreglass for your walls, use it for your ceiling too. This will save you money overall as you’ll be buying materials more in bulk, making it cheaper than switching the materials up. It will also be easier for beginners as you’re not overwhelming yourself with lots of different types of insulation.

Once you’ve taken a look at how much it will cost for your garage, you’ll need to consider the different areas that you need to insulate.

The Areas of your Garage to Insulate

You don’t need to insulate every single area of your garage, but of course the more you do, the better in terms of keeping the nice warm air in. Each area is important here as leaving one out could render a lot of your work useless.

Wall insulation:

You may not need to worry about this if your garage was built to the same standard as the rest of your house. However, many garages aren’t, so if you do need to insulate your walls, fiberglass is most commonly used. You will first need to remove the drywall in your garage (if you have it), clear up any dirt and remove any mould and chemicals.

Then look for gaps or cracks in the wall, use your expanding foam to fill them in, and then basically remove anything that shouldn’t be there or anything that will impact heat escape. After that you can install the fibreglass installation with drywall covering it, and you’re done.

This is perhaps the most important part of your garage to insulate, and you have many options, you don’t just have to use fibreglass. This will most likely be the part of your garage that takes the most time, material, and effort, but if done right, it could be the only part you need to insulate if you’re on a budget.

Ceiling insulation:

This is the one of the most important parts to insulate in your garage as heat rises and escapes by exiting out the roof. The process is very similar to insulating your garage walls, using thicker, R-40 insulation will do the trick.

Like I said earlier, you’ll want to use loose fibreglass with at least 3 inches thickness, installing this may be trickier than your walls so make sure you have someone with you for safety reasons if you’re not completely confident.

Garage door insulation:

This is as simple as buying a garage door insulation kit, these can be found on Amazon, and the process is similar to insulating the walls and ceiling, or you can buy an already-insulated door.

If you’re looking for guidance on how to install your garage door, check out my article on garage door installation.

Garage door insulation kits are usually pretty inexpensive and easy to install, my article on them which will be live soon, will show you the best, value for money ones you can buy now.

Door and window insulation:

This is the same as anywhere else in the house, Double glazing for the windows and insulating tape for your door should be more than enough.

These are the areas of the garage I’d recommend the least for insulating, as you may want to keep some fresh air coming into the room from your windows without having to open them each time.

Also, the air coming from your house through to your garage is likely to be warmer air than what’s outside. Therefore, you don’t need to concentrate on this area, but if you do, it’s very easy to as you can use the same tape as the tape from a garage insulation kit.

Garage floor insulation:

Although garage floors can get freezing especially if they’re concrete, you may not need to worry about this as much if you’re using underground heating. That being said, assuming your floor is concrete, you need to make sure it is level and moisture free. From there you can install wood sleepers with foam panels placed in between, or rigid foam insulation.

Therefore, the process for the floor is fairly similar to the walls. Just make sure to clear your whole garage first, if you’re planning on putting it outside, wait for some good weather!

If you’re looking to reinforce your garage floors and perhaps substitute the freezing cold concrete without the need to insulate it, be sure to check out my article on the best interlocking garage floor tiles.

Garage Insulation Tips

Using the same material is one tip, but I thought I’d be nice and give you a few more since you’ve made it this far:

Seal Gaps to keep the Draft Out

While you’re insulating your garage, you may notice certain gaps around your doors and/or windows. These will cause drafts and will undo some of your work while you’re insulating your garage. Therefore, be sure to seal them wherever they crop up with tape as nobody likes a cold draft in their garage.

Address any Moisture Problems

This is important to do before you start insulating your garage as any sort of water or moisture as a result from a leak in your roof or window will end up damaging your insulation.

There are many ways you can go about fixing this depending on the size of the leak. Smaller leaks may only require some waterproof tape, but bigger ones may require professional help. It is worth doing this right as you may have to remove the insulation you out on if the leak starts damaging your hard work.

Decide if/what Garage Insulation is Right for your Garage

Not every garage needs insulation. For example, if you’re not using any additional heating or cooling in your garage, it may be unnecessary to insulate it.

It is also worth weighing up costs/effort/time and what it will offer to your garage. If you only use your garage for storage and you don’t use it for a living or workspace, it’s probably not worth insulating your garage. The exception here might be if you’re storing objects that might rust, in that case, I’d recommend insulation.

Plus, if you’re using your garage just to store objects, it may be too much work to remove everything especially if you can’t fit it anywhere else easily. In this case, I’d recommend just doing the basics and checking for drafts, and insulating the windows, door, and garage door.

Consider Safety

Finally, garage insulation can involve getting your hands dirty, but if you want to keep your hands, make sure you’re diligent of your surroundings and invest in the correct protective gear for the job.

The right gear for this can include safety glasses, gloves, fibre-proof masks, pants, and long-sleeved shirts. But make sure you include common sense alongside your equipment, and you should be good to go.

Final Thoughts

Garage insulation is clearly very important, especially if you’re planning to use it as a multi-purpose room or a living space. Each type of garage insulation offers their own unique benefits and costs, the trick is to find the one that works the best for your garage.

Just be sure to take extra care to do the job properly as it will last years if done right but may be expensive and time consuming if it goes wrong.

That being said, if you think insulating your garage is the right option for you, I hope this guide helped you to understand how to go about it. Thank you for reading this far and please feel free to share this article if you found it useful.

garage insulation

James Johnson

What started out as an intention to create my dream garage has turned into a mission to share my research, whether that's guides or product recommendations, with as many people as possible. I believe that everyone should be proud of their garage, and by reading my guides, you are in good hands to make that a reality.


More to Explore