My Garage

How can I insulate my garage cheaply?

No matter what the weather is like outside, the temperature of your garage will typically follow the same temperature pattern. For the average homeowner, the garage is an area where temperature control can be a bit of a challenge.

The garage is well-known to be plagued by constant temperature fluctuations. Not only do these fluctuations have the potential to damage all the items you store in side, but it can wreak havok on your energy bills. Depending on the layout of your home, a poorly-insulated garage can ever have an affect on the temperature inside your home, especially within any rooms with a connecting wall to the garage.

So, what’s a homeowner to do? An easy solution is to add insulation to the garage door. Here’s why every homeowner should invest in this (relatively) cheap project.

Insulating a garage is a task you can perform yourself with a small budget even if you possess little to no insulating experience. With a bit of planning, some basic tools, and moderate mechanical skills, you can insulate your own garage quite easily.

Check out our range of garage renovations here. 

Why should you insulate your garage?

The most notable benefit of adding insulation in your garage is the ability to have better comfort over the temperature. However, there are many other benefits you can expect from this easy DIY improvement.

One important benefit is the amount of energy you can potentially save. This can equate to a dramatic slash in your bills long after the insulation has been installed.

Another lesser-known benefit is that it can help create a sound-proof environment, keeping sounds out or in, depending on your situation. For example, if you live on a busy street, garage insulation can help quiet the loud noise of traffic. Or, perhaps, you are using your garage as a workshop or to learn to play the drums, insulation will help prevent that noise pollution from becoming an annoyance to your neighbors.

My Garage

Do I Need to Heat My Insulated Garage?

Before you jump in, ask why you’re insulating your garage. If you’re trying to heat the space, keep in mind that insulation alone may not be enough. Depending on where you live and how cold it gets, you’ll also want to use a heating source for the room. Insulation simply helps to contain the temperature, whether hot or cold, and prevent it from escaping through the walls and ceiling.

How Much Does It Cost to Insulate a Garage?

Garage insulation costs vary based on the size of the space and the insulation you purchase. Sebring estimates it costs about 50 cents to $1.25 per square foot to insulate a garage. This means insulating a two-car garage would cost about $338 – $845.

What Type of Insulation Should I Use?

There are several different types of insulation you can use, but Sebring recommends using fiberglass insulation sold in rolls or batts (precut sections) to insulate your garage yourself. He says this is the easiest DIY choice.

Everything You Need to Insulate Your Garage

We can recommend which type of insulation to use and how to install it, but you’ll need to determine how much of each material you’ll need for your particular garage. Below are some guidelines for determining the quantity or type you’ll need of each material.

  • Fiberglass insulation: To find out how much insulation you’ll need, measure the linear feet around the entire room and multiply it by the height of the room to get the square footage. We recommend buying an extra unit of insulation. You can always return it if you don’t use it.
  • Garage door insulation kit: You don’t have to use a kit for the garage door, but we recommend it. Use this to find one that works for you.
  • Expanding foam: If you have gaps and cracks in your wall, you’ll need to fill them in to make sure outside temperatures don’t creep inside. Expanding foam comes in a low-expanding and high-expanding form. The kind you buy will depend on how big the spaces in your wall are. 
  • Drywall: The same measuring technique and purchasing recommendation as insulation applies.
  • Gloves and long sleeves: Fiberglass can irritate your skin. We suggest wearing gloves and clothing for protection.

Gather the Tools You’ll Need to Complete the Job

  • Sharp utility knife: This will be used to cut the insulation.
  • Wood: This will be used as a guide on top of the insulation to make it easier to cut it down to the right size.
  • Staple gun and staples: These will be used to staple the insulation into place.

The Cheapest Way to Insulate a Garage


Choosing the cheapest type of insulation for your garage will depend on a few factors, such as the climate you live in and the construction of the garage itself. All insulation is rated with an R-value, which indicates the material’s ability to resist heat conduction. A higher R-value means that the material insulates better and is optimal for colder climates. Consult with a professional to determine what R-value will be the most beneficial for your location.

The two most popular materials for garage insulation are cellulose and fiberglass roll insulation. Fiberglass roll insulation is easily unrolled and installed on horizontal surfaces, but for vertical surfaces it must be installed behind the walls, which makes it preferable for garages that have not been fully constructed. Cellulose insulation is a recycled loose-fill insulation that can be blown into walls and attics, making it the ideal choice for garages that have been finished.

Types of Insulation for Your Garage

Insulating a garage makes sense if you’re planning to heat the space. When it comes to choosing materials, you can use the same types of insulation used on the rest of the house, but some are better than others, depending on whether the garage is finished or not. You also want to look at insulating the garage door, which has different installation requirements than walls or ceilings. 

Garage Insulation Basics

It pays to insulate your garage if you’re adding heat, whether on a permanent or as-needed basis. If you’re not adding heat, there’s little point in insulating. It’s a popular misconception that insulation adds warmth. In reality, insulation merely slows the transfer of heat through the insulated barrier (wall, ceiling, floor, etc.).

There is a school that maintains that an unheated garage that is attached to the house may get some benefit from insulating the walls and ceilings of the garage since it theoretically offers an additional thermal buffer between the exterior of the home and the outdoors. But no state requires this as part of energy-efficiency mandates, and it is unlikely that this minimum improvement in energy transfer will offset the costs of extensive insulation. The walls that are shared with the house, however, should obviously be insulated to their maximum value.

It’s also important to realize the value of air-sealing in conjunction with insulation. Garages typically aren’t built to be airtight and have lots of air gaps to the outdoors. You can insulate the walls, ceiling, and door of the garage to the highest R-value possible, but if you fail to fill those air gaps, you’ll still be wasting a lot of heat. So before insulating, go around the garage with a can of low-expanding spray foam and seal all gaps and cracks that let in the daylight. (Of course, your garage door is essentially a gigantic air gap when it’s open, but that’s another matter.) Also, make sure weatherstripping along the bottom of the garage door and along window and door frames are intact to seal against drafts.

Hitch Property Constructions has the biggest range of the garage renovations Melbourne. Check it out here.

Fiberglass Insulation

Fiberglass is the most commonly used type of insulation in garages (just as it’s the most popular type in homes). It’s sold in pre-cut batts and long blankets that fit between wall studs and ceiling joists. You can also get loose-fill fiberglass, which it suitable for blowing into a garage attic space above a finished ceiling.

If the walls and ceiling will remain open (not covered with drywall or plywood), it’s a good idea to use paper-faced or encapsulated fiberglass bats that are wrapped in a plastic film. These will give the walls a slightly more finished look, and you won’t have the itchy fibers of the insulation exposed and ready to catch dust at all times.

Fiberglass roll insulation is the cheapest and easiest type to install, provided that your garage’s interior walls have not been constructed. Unroll the insulation between the wall studs with the vapor barrier facing the inside of the garage. Use a staple gun to set 1/2-inch staples every 2 feet along the edge of the insulation into the studs so that it stays snug. For attics and horizontal surfaces, simply unroll the insulation between the joists and allow it to lay flat — it is not necessary to secure it down with any fasteners. It is important not to compress fiberglass roll insulation because it will lose some of its insulating effectiveness.

Cellulose Insulation

Cellulose is a loose-fill insulation that is growing in popularity. Made primarily from recycled newspapers and treated with a fire retardant, cellulose is usually blown into wall and ceiling cavities with a special blowing machine that also aerates the cellulose and fluffs it up. Blowers can be rented at many tool rental stores, and home centers will sometimes loan you a free one if you buy your cellulose from them.

Because it’s loose-fill, cellulose is suitable only for finished garage walls and ceilings. If the garage is already finished (but uninsulated), you can install cellulose by cutting strategic holes in the wall material, spraying the insulating into the cavities between framing members, then patching the holes.

Cellulose insulation will cost a bit more to install because you will probably have to rent an insulation blowing machine. It still remains the cheapest option, however, if your garage is already finished with interior walls. Use a staple gun with 3/4-inch staples to attach rafter vents into the wood framework adjacent to any soffit vents. The rafter vents will prevent any cellulose insulation from blocking airflow into the soffit vents.

Prepare an insulation blowing machine according to the manufacturer’s instructions and route the output hose into the crawl space above the garage. Start the machine and manipulate the hose from the crawl space so that the cellulose insulation is blown downward into the vacant wall spaces. Each space along the perimeter of the garage should be filled to the top with the cellulose insulation. After all walls are completely filled with insulation, continue blowing the material onto the attic floor to insulate the ceiling.

Rigid Foam Insulation

Rigid foam comes in 4 x 8-foot sheets and thicknesses of 1/2 inch to 4 inches. The most common materials include expanded polystyrene (similar to Styrofoam), extruded polystyrene, and polyisocyanurate. Rigid foam offers a high R-value per inch of thickness and can be cut to fit almost any space. It’s a good choice for thin walls and for insulating garage doors. If you’re turning the garage into living space or a full-time workspace and want to insulate the floor, one option is to use rigid foam covered in plywood or other subfloor material.

  • Note: Check the fire rating on rigid foam; some types are not fire-resistant and are not suitable for exposed applications.&

Spray Foam Insulation

Spray foam is excellent for both R-value and for air-sealing. As a high-end material typically used for energy-efficient construction, spray foam is overkill for most garage projects. But it might make sense if you’re converting the garage to living space.

Garage Door Insulation

Don’t insulate your garage walls and ceiling without insulating the big garage door, too. You can buy insulation kits for standard metal garage doors, or you can cut pieces of rigid foam insulation to fit each door panel/section. Keep in mind that the structural metal ribbing of garage doors is an excellent conductor of heat, and this typically doesn’t get insulated. As a result, the overall thermal performance of the door will be well below the rated performance of the insulation itself.

Air-sealing is particularly important with garage doors. Create a seal along sides and top of the door with special garage door trim with an integrated weatherseal strip. Seal along the bottom of the door with a new rubber gasket, or “bottom seal.” It’s available in different sizes to cover small or large gaps between the door and the garage floor.

Areas You Can Add Insulation

Within your garage, you have three main areas in which you can add insulation. While it would be ideal to sure all three areas are properly insulated, it’s not always going to be feasible, as least not for the average homeowner.

Garage Door

The easiest and cheapest area is to add insulation on your garage door. You can buy different types of insulation or buy a garage door insulation kit that has everything you need. Either way you go, this DIY project should only take a few hours to complete, and will save you thousands of dollars over the course of its lifetime.

As the main barrier to the exterior, adding insulation on your garage door is strongly recommended for every homeowner. This is especially true for anyone that has an interior wall connected to the garage.

Garage Walls

Adding insulation to your garage walls is going to be a little more complex of a project. Likely, this is one area you shouldn’t need to be concerned about as homes, by law, are built with insulation in the walls. This is primarily due to the fire hazards associated with garages. Specifically, the type of combustible materials stored in the area, as well as the fact that most garages do not have a smoke detector.

Regardless, insulating the walls in your garage is something you should consider, especially when your home has an interior wall connected to it.

The Ceiling

The often forgotten about area in your garage, the ceiling is an incredibly important area to have insulation. If you have a bedroom directly above the garage, that room will experience the wrath of the weather outside if your garage does not have proper insulation.

Of course, adding insulation inside a ceiling is a very complex project that your average homeowner will be hesitant to embark on. You would need to consider the air flow and whether condensation may build up, which could lead to mold. This is definitely a job for a professional.

While installing insulation in the ceiling of your garage will certainly slash your energy bills and add comfort to the room above, it’s going to be significantly more expensive and time-consuming to complete and you may never fully see a return on your investment.

Do I need to insulate my garage?

You should only insulate a room if it contributes to the comfort of the inhabitants or to the protection of objects, systems or installations housed there.

If you are only using your garage to store a vehicle, it is not necessary to insulate the space. Vehicles are designed to survive out in the elements and are therefore protected in a non-insulated garage.

However, the need for insulation changes if your heating system is located in the garage, a space has been reserved there for washing, or you use the garage for activities where a certain degree of comfort is required.

In such cases, it is appropriate to insulate your garage, which would thereby incorporate it into the protected volume (i.e. all heated rooms in the housing unit).

Sensible design

When designing your residence, it all comes down to making informed choices. The decisions you make affect the net energy demand of the residence.

If the garage is within the protected volume, the total energy demand will be higher. The exact degree to which energy consumption is affected depends on the surface area, orientation and solar gain.

No other option

You may have no other option but to incorporate the garage into the protected volume. In a terraced or semi-detached house, it may be cheaper to incorporate the garage into the protected volume, for example if it is completely surrounded by a protected volume.

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What should I insulate?

If the garage is outside the protected volume:

  • Insulate the inner walls between the garage and residence
  • Install a door between the garage and residence with sufficient insulation

If the garage is inside the protected volume:

  • Insulate the outer walls
  • Depending on the situation, you may also need to insulate the floor and the roof of the garage
  • The garage door is also important to consider. As with other parts of a building, a garage door should meet the maximum U values stipulated in energy regulations.

Insulating a garage door might sound like a daunting task, but as you can see, you can complete this project in just a couple of hours. If you are not up to fork out thousands of dollars for an insulated door, cheap foam board or batting is the way to go. Just be sure to select the right type of material for your particular climatic zone to realize the energy-saving benefits of insulating your garage.

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