Want To Slash Your Heating Bills? This Is the Garage Insulation You Need

Insulating the garage is a great way to ensure that the space can be used all year round and that the items stored inside are safe from extreme temperature fluctuations. Even just insulating your garage door can make a big difference in how much heat loss the space experiences (and how much your heating bill costs you). Before you start to insulate the garage, it’s important to consider what type of insulation is best for your garage walls and garage door based on the climate and how the space will be used. 

Some types of insulation are cheap and easy to use, but they may come with significant drawbacks, like being vulnerable to fire. To make the best choice about the type of garage insulation that is right for your home, it’s recommended to learn more about the various garage insulation types, so that you can make an educated decision before proceeding with your installation.  

Fiberglass Batts 

Fiberglass batts are often a top choice for DIY installation due to the low price to purchase the material and the relative versatility of the batts, which make it easier to handle. Steve King, workshop operation manager at Sheds Unlimited, says “fiberglass batts are widely available and budget-friendly, easy to use or at least familiar to most DIYers already, easy to cut to fit, and it works well in open framing. However, it can be less effective if it's super compressed or if it's installed with gaps, it can also trap moisture if installed without a proper air barrier, it’s not pest-proof, and it can get messy or damaged.”

Pros:

• Affordable and widely available: One of the most budget-friendly options, found easily at most home improvement stores.
• Good thermal performance: Offers high R-values (around R-3 to R-4.3 per inch) to keep homes warm in winter and cool in summer.
• Fire resistant: It's a non-combustible material, adding a layer of fire safety.
• DIY-friendly: Available in pre-cut batts, making it relatively easy for homeowners to install in standard framing.
• Environmentally conscious: Often made with a significant percentage (20 to 30 percent or more) of recycled glass.
• Sound dampening: Provides some noise reduction.

Cons:

• Poor air sealing: Doesn't naturally block air; gaps allow drafts, requiring separate air sealing and vapor barriers for best results.
• Moisture sensitive: Absorbs water, which drastically reduces its R-value and can lead to mold/mildew if it gets damp.
• Health hazards: Fine glass fibers can cause skin irritation, itching, and respiratory issues during installation.
• Installation sensitivity: Needs precise cutting and fitting to avoid gaps; compression reduces R-value.
• Can settle/degrade: May lose effectiveness over time, especially if not installed perfectly or in high-moisture areas.

Related: 9 Best Winter Garage Maintenance Tips for Homeowners

Rigid Foam Board

Rigid foam board is excellent for garage doors, since it can be cut cleanly to fit into the panels. Though, when you are using it for the walls or ceiling of the garage, it’s important to consider the potential drawbacks. King explains that “it will be more expensive than more basic options, it also needs to be carefully installed, especially at the seams, to make sure it performs well, and a lot of places will require that it is covered with a fire-code-approved barrier (like drywall). Though, it works well on concrete or block walls where you can’t as easily add other types of insulation, it can double as an air and moisture barrier when seams are taped and edges are sealed, its thin profile helps insulate tight spaces and in places like overhead door tracks.”

Pros:

• Excellent thermal performance: High R-value per inch, providing superior insulation and reducing heat transfer.
• Moisture resistance: Resists water and dampness, preventing mold and rot, great for basements and exterior walls.
• Air sealing: Creates a tight building envelope, blocking drafts and improving indoor air quality.
• Versatile: Usable in walls, roofs, floors, and foundations.
• Durable and stable: Doesn't settle or shift like some other insulations, maintaining performance.

Cons:

• Higher cost: More expensive material and installation than fiberglass.
• Installation challenges: Requires precise cutting and meticulous seam sealing, making DIY tricky.
• Fire hazard: Not fire-resistant; emits toxic fumes if it burns, requiring proper covering (like drywall).
• Pest vulnerability: Can attract pests like termites if exposed or damp.
• Environmental concerns: Petroleum-based, with potential for off-gassing.
• Leak detection issues: Can hide water leaks or pest infestations due to its dense nature.

Spray Foam Insulation

Installing spray foam insulation in the garage is a costly, but long-lasting choice that can greatly reduce energy waste and help keep the garage feeling comfortable in both the winter and summer months. “Spray foam is usually going to be one of your more expensive options. It also should be handled by a professional who has the right equipment and safety knowledge. Spray foam is hard to modify once it’s installed. Truthfully, it might be overkill for some garages, especially detached garages, but it is probably the best at keeping heat in during winter and out in the summer. It’s also excellent at air sealing, it’s great for reducing drafts and temperature swings, and closed-cell spray foam in particular adds a significant moisture barrier,” says King.

Pros:

• Superior air sealing: It expands to fill gaps and cracks, creating an airtight seal that prevents drafts and reduces air infiltration, improving indoor air quality and comfort.
• High R-value: Spray foam offers a high R-value per inch, providing more insulation in a smaller space, which is especially beneficial in tight areas.
• Energy efficiency: The airtight seal and high insulation value can significantly reduce energy consumption for heating and cooling, leading to long-term savings that can offset the initial cost.
• Moisture barrier: Closed-cell spray foam can act as a vapor retarder, preventing moisture from passing through, and it does not absorb water.
• Structural support: Closed-cell foam can add structural rigidity to walls.
• Resists mold and pests: As a synthetic material, it does not support mold growth and is not a food source for pests like fiberglass or cellulose can be. 

Cons:

• High upfront cost: The initial cost is generally higher than other insulation options like fiberglass.
• Professional installation required: Proper mixing and application are critical and require professional, licensed contractors. Incorrect installation can lead to a "fishy" smell, gaps, or other issues.
• Potential for moisture problems: Closed-cell foam can trap moisture from leaks, preventing it from drying out and potentially causing rot, especially in older homes with leaky roofs.
• Needs proper ventilation: The extreme airtightness can require a proper ventilation system to prevent issues like carbon monoxide buildup or superheating.
• Difficult for DIYers: The complex process, including the need for extensive safety precautions, makes it unsuitable for DIY projects.
• Difficult to remove: Once installed, it can be very difficult to remove, which is a major drawback when electrical work or other renovations are needed.

Related: Most Homeowners Forget This Critical Garage Door Tune-Up. Are You One of Them?

Radiant Barrier Insulation

Radiant barrier insulation can also be known as reflective barrier insulation because it has a reflective layer that is specifically designed to reflect heat. This type of insulation is best for warm climates, as it is primarily intended to reduce heat, but is not as effective when it comes to heat retention during the cold months of winter. Ideally, radiant barrier insulation will be used with thermal insulation, like fiberglass batts or blown-in cellulose, to maximize efficiency both during the summer and winter months of the year. 

Pros:

• Reduces cooling costs: Effectively lowers heat gain, significantly decreasing air conditioning use and energy bills in hot climates.
• Works in hot climates: Ideal for sunny regions because it reflects radiant heat away from the home.
• Lowers attic temperatures: Can drastically reduce attic temperatures, keeping stored items cooler and lessening strain on your AC.
• Durable and low maintenance: Made of reflective material, it's long-lasting and doesn't suffer from mold, pests, or insects like some other insulations.
• Easy installation: Radiant barrier sheathing can be inexpensive and doesn't usually require special tools.

Cons:

• Limited cold-climate value: Provides minimal benefit in cold regions where you need to keep heat in, not reflect it out.
• Doesn't add R-value: It reflects radiant heat but doesn't stop conductive or convective heat transfer, so it doesn't replace thermal insulation.
• Requires air gap: Needs an open air space next to the reflective surface to work; if installed directly against insulation, it loses effectiveness.
• Moisture/condensation risk: Can cause ducts to sweat (condense water) in humid climates if the attic gets too cool, leading to mold.
• Installation critical: Effectiveness hinges on correct installation, facing the air space and covering the right surfaces.

Related: Experts Reveal the Most Durable Garage Floor Coating You Can Buy

Blown-in Cellulose and Fiberglass

Blown-in cellulose or fiberglass are relatively affordable options for the garage, though this type of insulation is more commonly used in attics. King notes that “it’s not exactly DIY friendly; you usually will need special blowing equipment and some experience. It will also settle if it's installed incorrectly, which will cause gapping at the top of walls, and, same as above, it needs to be carefully air-sealed to avoid moisture problems. However, if done correctly, it will fill cavities more completely than batt application, it offers pretty good sound insulation if the garage shares a wall with a living space, and it's made from recycled materials, which a lot of people like.”

Pros:

• Excellent coverage and air sealing: Fills gaps, cracks, and hard-to-reach areas, creating a dense, seamless barrier that stops drafts better than batts.
• Energy efficiency: Reduces heating and cooling costs by improving thermal performance.
• Cost-effective: Often cheaper and faster to install than other options like spray foam, with lower material use.
• Good sound dampening: Cellulose and fiberglass help reduce noise transmission.
• Fire resistant: Materials like fiberglass and treated cellulose are naturally fire-retardant.
• Ideal for retrofits: Easy to install in existing homes, especially attics, without major disruption. 

Cons:

• Settling: Can compress over time (especially cellulose), reducing effectiveness and R-value.
• Moisture vulnerability: Can absorb water if there are leaks, leading to mold, mildew, and reduced R-value (cellulose is more prone).
• Air quality concerns: Can potentially trap allergens; needs proper ventilation and vapor barriers.
• Pest attraction: Can provide habitat for rodents if not properly sealed.
• Installation quality: Inconsistent depth or gaps can compromise performance, requiring professional installation.
• Weight (cellulose): Heavy cellulose can potentially damage older drywall or ceilings if applied too thick.

Related: How to Insulate Your Garage for Major Energy Savings This Winter

How to Pick the Right Type of Insulation for Your Garage

Deciding on the right type of insulation for your garage depends heavily on how you use the garage and the local climate. For instance, you won’t need to use spray foam insulation to insulate an attached garage in Florida, but spray foam may be the best choice for an attached garage in Minnesota, especially if you intend to use it as a workshop or home gym during the winter months of the year.

King explains that “an attached garage might need a heavier-duty insulation option because it will affect the temp/energy use of the house, but a detached garage will not. If the garage will be heated or air-conditioned, or if it has a living space above it or attached somewhere, then you might need a stronger option, something like spray foam or a combination. However, a simple, storage-only, unheated garage can be made cost-effective with options like fiberglass batts and a sturdy door.”

When is the Best Time to Insulate Your Garage?

Generally, the best time of the year to insulate the garage will be during the spring or the fall when the weather outside is mild and easy to work in. King also notes that it’s a good idea to “insulate a garage during its construction or during a major remodel. You need your framing to be exposed so that you can seal everything correctly (as well as coordinate any electrical, plumbing, heating/cooling additions).”

Related: The Ultimate Home Maintenance Checklist: Essential Tasks You Should Do Each Season

Can You Insulate Your Garage Yourself?

It is possible to insulate a garage yourself if you have the skills, materials, and general know-how. Though, there are some types of insulation that are best left to the pros, like spray foam or blown-in insulation, so it’s important to gauge your abilities accurately before deciding to take on a garage insulation project alone. 

“Depending on the size of your garage and your chosen insulation option, it’s reasonable that some DIYers can handle insulating with some basic tools and good instructions. Many homeowners could handle fiberglass batts, rigid foam on concrete walls, and sealing cracks with caulk or canned foam. Be sure to have gloves, eye protection, and a mask or respirator if working with fibers or spray products, and check any local code requirements first,” King says. 

When Should You Hire a Professional?

Whether you need to hire a pro or not depends on a few important factors. The first to consider is your own skill level. If you aren’t sure how to insulate a garage or you are not confident in your ability to insulate the garage properly, then it’s better to have a pro handle the work. Another factor is the type of insulation you are using. It’s usually better to have pros handle insulation that requires specialized tools for the installation, like spray foam or blown-in insulation.

You should also consider the current state of the garage. Professionals will be able to identify any problems, like mold, mildew, moisture incursion, and air leaks, then suggest or complete repairs before proceeding, while the average DIYer may miss these issues. “Professional help makes the most sense when you’re dealing with spray foam or dense-pack cellulose, as well as in any garage that is next to a living space, and if there’s evidence of existing mold or concern about moisture or air quality,” explains King.