How Can You Insulate Garage Walls That Already Has Drywall Up? (Step-by-Step Guide)

You don’t need to remove the drywall to insulate a garage as it will distort the aesthetic appearance of your garage. You can drill small holes and fill them using injection foam insulation. Alternatively, you can blow in the insulation as it is more straightforward.

The signs of air leaks are indicators that your garage needs insulation, even if it has a drywall up. You can save up to 10% of your energy costs by insulating your garage. Still in doubt? 

Read on to learn about garage insulation, drywall, and more. 

Importance Of insulating Garage Walls

Insulation of a garage wall should not be burdensome. In fact, it is worth it. But why can’t you replace the whole garage instead of insulating it? Is there any benefit of doing that? Yes. Let’s check it out.

There are numerous benefits associated with insulating your garage wall after drywall. It will cut down on the energy costs and make your garage more contented

By drilling small holes, you will also prevent damaging the items in the store within the garage’s store. You also soundproof your garage when you decide to insulate compared to constructing a new one.

Furthermore, you will curb precipitation effects like ice condensing on the floor of your garage. Therefore, it will be essential to insulate your garage wall, primarily if you reside in regions experiencing the winter season. 

Lastly, you will keep your garage warmer to make sure your cars last longer. 

After looking at these benefits, you must be interested in doing the insulation without doing away with the drywall. Check below how to do it. 

Insulation Methods For Garage That Already Has A Drywall

Using Injection Foam Insulation

You can insulate the drywall using injection foam insulation. This method involves filling holes and cavities using a resin agent and an aqueous solution. When the mixture dries, it hardens to form a sturdy insulation layer. 

The better part, this method is easy, fast, and reasonably priced. Unlike other methods where you have to spend so much, the labor cost begins from as low as $0.44 per square foot. Such cheap prices are enchanting, especially when your drywall remains intact while you only need to guide the person doing it. 

Spray Foam Insulation

Similar to injection form insulation, this method can be a perfect choice when you want your garage insulated while retraining the drywall. In a nutshell, the whole idea is about spraying a poly material that acts as an insulator. It either expands or contracts with the environmental temperature. The advantage of spray foam insulation is that it expands when the garage is warm to fill all the crevices, including smaller spaces. 

This way, neither warm air escapes from your garage nor does cold air penetrate outside. But, the method doesn’t work everywhere. Usually, foam insulation works well with roof rafters. It is one of the most effective ways of garage insulation because of the high R-value of the poly material used. So, what’s, does the R-value mean when talking about insulation? Let’s break it down.

What Is The R-value For Garage Insulation?

In simple terms, the R-value is the ability of an insulating material to repel heat loss. You can use it to determine the thermal efficiency of the insulating material for your garage. Usually, this value ranges from 1.5 to 7. A fabric with a higher R-value has the best insulation properties, while a lower R-value indicates poor thermal properties.

Hint: Choose a material with a higher R-value when insulating your garage. That’s firsthand information that you should know before selecting an insulating material. 

Now that you know how to get the suitable material let’s see how to insulate your garage.

How To Insulate A Garage?

Before we move to the anticipated step-by-step guide on how to insulate a garage, getting to know the exact area you need to insulate is crucial. 

First, get the linear measurements and multiply them with the height of your garage. However, you can add measurements as you can always have to preserve the leftovers for an emergency. The additional measurements will also be indispensable in the unlikely event that you overuse the insulation materials.

In addition, it is best to use fiberglass insulation for your garage. It is an insulating material made up of glass fibers sold in rolls. It is highly recommended due to its thickness with various R values, giving you a wide range of fiberglass materials to choose from. 

Step # 1: Clear Everything From The Wall

Remove all the dirt and mold by using suitable chemicals and detergents. You may use bleach if possible. For the drywall, you may choose to remove or leave it because you can still work without putting it away.

Step # 2: Fill The Crevices In The Wall

Shake your foam, insert a pipe in the can, and turn it upside down. Start spraying the crevices in the wall as long as you fill them halfway. The foam will expand until it covers the entire space, probably after 8 hours.

Step # 3: Install The Fiberglass

Using a stapler and pins, fix the paper on the stud’s sides. If you have removed the drywall, you will have to fix it in the stud’s face, where you should leave some space as you install the fiberglass. 

Step # 4: Seal The Insulation

Preferably, you can use glue to stick the fiberglass on the stud. Also, ensure the insulating paper is not exposed to mitigate any fire risk. 

The steps above are meant for the wall insulation that your garage needs. Nevertheless, it is insufficient to keep your garage warm during winter and at room temperature in hot summer. That’s why you will also need to insulate the roof and the doors—still interested? Let’s check out how you can insulate the roof and the door(s). 

Insulating The Roof And Door Of A Garage

Roof Insulation

The ceiling is more accessible, and the steps are almost similar to wall insulation. The only difference is that you will need to use a material with a higher R-value because most of the heat escapes through the roof. 

Reminder: Get the width and height measurements and cut all the pieces you need while on the ladder. It will save on time rather than climbing and coming down to pick the materials every time.

Insulating Garage Door

Next is insulating your garage door. Dissimilar to the insulation of walls and the ceiling, the process might be a bit involved, especially if you prefer doing it without professional help. Even experts would prefer that you purchase doors that are already insulated. Besides cutting down on the cost, it is easier to work with readily insulated doors. 

If you choose to do it the DIY way, buy a garage door insulation kit. It will make work more manageable since the kit comes with all the needed tools. Once you have the kit, follow the insulating walls and the ceiling steps, and you are done. Once again, fiberglass is the most recommended material, but you can also use batts and rolls. There are numerous advantages when you choose fiberglass, and here are the reasons.

Why Fiberglass Is Recommended Over Other Insulation Materials

Fiberglass is recommended for a reason. Fiberglass is multipurpose and can be used for doors, ceilings, and floors. Furthermore, it is also easy to use, affordable, and highly available in the marketplace. 

Pro & Cons Of Brickbats, Blankets, And Cotton Batts

Going for other materials instead of fiberglass has many cons than pros. Check them below:


1. Less dusty

2. Fire resistant

3. Health-friendly 


1. High moisture retention capabilities

2. They are expensive

3. Require special installation equipment

4. Vulnerable to destruction by pests and insects

5. They are bulky

Better Substitutes For Drywalls 

The advantages of fiberglass favor the drywalls being insulated in a garage. Sometimes all these processes may appear hectic, and you want to get a better alternative to drywalls. 

Why do drywalls work well for many places? They may not be the best for your garage. Before setting up drywall, you can consider other materials that will enhance the beauty of your garage. Of course, clients will also be attracted by the artistic appearance of your garage besides offering high-quality services. 

Wood Sheathing can be a better alternative, beginning with the ease of use to the whole process of installation. It can be suitable for framing since you only have to use screws when fixing your garage. The best part, it doesn’t require tapping, as is the case with drywalls. 

Cement Boards can also be suitable substitutes for drywalls. Unlike drywalls, you are free to add tiles within your garage with a combination of veneer. Surprisingly, your garage will have a rusty appeal yet is easy to maintain due to the durability of cement boards. 

Final Thought

To sum up, we have covered all requirements for insulating a garage with or without drywall, how to do it, and choosing the best insulation material. Now that you have all the necessary information about insulating your garage, why can’t you give it a try? 

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