What is the R-Value of an Insulated Garage Door?

In the wake of all the craziness happening in the world right now, I’ve found myself spending more time in the woodshop in my garage. It’s relaxing – I build, I tinker, and sometimes I find something that is marketable, and I sell some of what I make. A buddy of mine recently reached out when he saw some acoustic panels that I had built and posted on Instagram. He was telling me about how he has gotten back into the woodshop too and how it had once again has taken over his garage. As I looked over the stacks and piles of wood I had accumulated, the array of clamps and the new table saw jig I had just put together, I chuckled. I could completely relate.

As we were talking about our projects and which new tools we had both scored in the name of forward progress, our conversation turned to our working conditions. It had been no joke trying to weather the hottest summer in recorded history out here in Phoenix while trying to get orders fulfilled.

He tossed around the idea of having an ac unit installed into the garage wall. This got me thinking about what other steps he could take to insulate his garage, so the ac did not have to work so hard. I suggested insulating the garage door. We started doing some research into this upgrade and were confronted with some new information. The question was then asked, “What is the R value of an insulated garage door?”

What is the R-Value of an Insulated Garage Door? Keeping your garage insulated via the garage door is a must if you do any kind of work in any extreme temperatures. But what is R-Value? And what does it tell you about how well your door is insulated?

If you are looking at insulating a garage door as a DIY project, the R-value of an insulated garage door can vary slightly depending on the material that you used to insulate the cavities. A typical aluminum garage door has an R-value of 0 (that is zero), which means heat is rapidly entering or leaving your garage depending on the season. Most garage door insulation kits will provide you with an R-value of 8 (R–8) once installed properly. For garage doors that are built and insulated at the factory, R-value can range greatly starting around R-8 on the low-end and can go up to R-32 on the high-end with the treatment options that can be performed during fabrication.

What is R-Value?

If you have never heard of R-value before, R-value represents resistance to heat flow. Basically, it is a measure of how resistant the material is from heat transferring through the insulative material.

In nearly every case when it comes to insulation, the bigger the number, the better for you. Now, having an R-value ranging from R-4 to R-8 might not sound a lot. Especially since the typical roll that you see at one of the big box stores starts at R-13, and insulation for ceiling can get well into the 30’s and beyond.

In comparison, you would be right. It is difficult to compare your R-38 ceiling with layers of insulation overhead of 13”-14″ thick, versus the limited space you have in the cavities of your garage door.

But you have to work within the limits you have, and the space you have for that matter, so that you better control the temperatures within your garage space.

What is the R-Value of an Insulated Garage Door After Installing a Garage Door Insulation Kit?

When it comes to the R-value of a DIY insulated garage door, there are limitations on the R-value that you will be able to work around some. When installing the garage door insulation, you are adhering the insulation into the large flat panels of the door between the flex joints.

When you use an insulation kit to insulate the garage door, you are covering the majority of the door in insulation, but the aluminum around the outer frame and around the flex joints are still going to allow heat to radiate through the metal. This is why you will see R-values ranging from around R-4 to R-8.

You are probably now asking if it is worth the cost and effort if you are not able to achieve a higher R-value with your insulated garage door. Well, the answer is still Yes! By providing your garage door with some heat transfer resistance, it will reduce how drastic the temperature changes in the thick of winter and summer.

For example, in the winter, the insulated garage door will help keep your garage about 10 degrees warmer. These 10 degrees can be the difference between something freezing and causing damage when the temperature drops or keeping you and your things problem-free in the dead of winter.

The same can happen in the summertime when you are working in your garage without an ac unit to cool the space. Speaking from experience, an insulated garage door is what makes the space semi-tolerable when it has been 116 degrees (46.6 Celsius) in the shade. Without being insulated, that aluminum door would heat up and would let temperatures of 140+ radiate in.

What is the R-Value of an Insulated Garage Door for Newly Fabricated Garage Doors?

If you are considering garage door replacement and are someone who is often working or tinkering out in the garage, we suggest you consider an insulated garage door with a high R-value.

Insulated garage doors that were insulated at the factory are far more energy efficient and have a much higher overall R-value. On the low-end, like garage doors that you insulate yourself, these insulated garage doors start at an R-8 rating.

On the high-end, insulated garage doors can range up to an R-32. This will greatly help when it comes to controlling the temperature of your garage. If you do spend a lot of time in the garage, consider upgrading your potential garage door to make the time you spend in the garage during the more extreme times of the year more comfortable.

The reason that the R-value of an insulate garage door that was insulated during fabrication has a much higher is because the manufacturer is able to close up the majority of the air gaps, providing a better barrier from the weather.

 Are There Other Ways to Increase the R-value of an Insulated Garage Door?

Beyond just wondering what is the R-value of an insulated garage door, the next follow up question normally is how can I increase it? If you are looking for more temperature control for your garage, we recommend that you also consider a radiant barrier.

Radiant barrier, also called bubble insulation or insulation foil is normally made of aluminum foil. Since aluminum foil is highly reflective, the radiant barrier reflects heat waves rather than simply resisting the heat from transferring.

The benefit of using both insulation and a radiant barrier when insulated a garage door is that it provides two different defenses from heat transferring through your garage door.

Some kits you find will have a combination of insulation and a radiant barrier. We suggest that you consider one of these kits when purchasing insulation to insulate your garage. The dual barrier will increase the R-value of the insulated garage door and will make it easier to control the temperature when working out in the shop.

Final Thoughts

I’m not sure about yours, but our garage’s functionality has changed over the years. Beyond just a place to park the cars, it has been used for storage, a proving ground of sorts for remodeling the house, and now a woodshop for me. We have gone in and out of seasons of being concerned with the extreme temperatures of the garage. And truthfully, I haven’t always been in a place to do much about it. After talking with my buddy, I could tell his experience had been similar. The mindset completely changed though when he started working on projects out in the extreme heat. Knowing the R-value you can achieve by insulating your garage door can help make the space more comfortable and will help protect the tools and items stored in the garage space.

If you would like to know more about the benefits of using garage door insulation, check out our article “6 Benefits of Garage Door Insulation.” R-value and temperature control are major factors when it comes to an insulated garage door, but there are other benefits to taking on the project as well.

Is this a project you might try to DIY? Are you concerned about how difficult it might be, or the process of doing so? The Garage Junkie has an article for that too! Check out “How to Insulate Your Garage Door” for more information.