You need to think about all the areas of your garage when you plan to insulate it including the ceiling and garage doors as well as the walls when you plan to add a cooling and/or heating system. You also need to take the type of flooring you have in the garage into account, which may or not need to be insulated as well.
What type of insulation you use, whether it’s a spray, blanket or batt, or blow-in, will also be a big consideration. Some of the insulation types need to be put in by a professional while others you can do on your own. Besides keeping out cold and keeping in heat, insulation can also keep out noise if that’s important to you. Here is more information on the types of insulation available as well as a step-by-step guide on how to insulate a garage.
Preparing Your Garage For Insulation
First, you will need to decide the size of the space you want to insulate. Next, add 10 to 20 percent that will account for odd spaces that you will need to fill as well as mistakes. Also, count in the areas above windows and doors and remember to measure the area between studs and joists to decide the insulation width that you will need. A typical rule of thumb is that these areas are spaced 16 inches on center, however, this may vary.

Second, choose the type of insulation you will be using. Fiberglass is usually the most common when considering blankets and batts with many natural options on the market. Make sure that you choose an insulation type that is not made with formaldehyde.
Third, determine your square footage number and then divide it by the square footage that each package or roll of insulation will cover. That number will tell you how many rolls or packages of insulation that you will need to buy. Then install as it directs, which typically involves cutting it to fit and then using a staple gun to make sure the vapor barrier is attached to the studs.
When you put in new garage doors, also make sure you install insulation. If you have old, uninsulated doors, then you can buy a retrofit kit that will add insulation panels.
If you want to keep your garage floor more comfortable in the winter months, add PVC mats or interlocking foam mats. Not only will they offer a little more insulating effectiveness, but they will keep the floor cushier and warmer under your feet.
Heating an Insulated Garage
Before you start the insulation process, ask yourself why you are insulating your garage. If you want to heat up space, consider that insulation by itself may not be enough depending on where you live and how cold the temperatures get there. You may also want to bring in a heating source for the garage. All insulation does is help contain the temperature that already exists, whether it’s cold or hot, and will prevent it from getting out through the ceiling and walls.
Types of Rolls and Batts Insulation
This is an easy to handle insulation that is used between framing. You can use it in any area including ceilings, floors, and walls. However, it’s widely available and can retain moisture, and some types can get pretty pricey.
- Loose-fill fiberglass– This is a loose application that tends to lose up to ½ of its effectiveness. Loose-fill fiberglass needs a special machine to install it and can be difficult to install in some areas.
- Loose-fill cellulose – Depending on where it is used, loose-fill cellulose can be too heavy and can require added work like framing and drywall. Remember that this type of insulation may settle over time, which can reduce its effectiveness.
- Polystyrene structural insulated panel – These panels can be cut it fit around outlets and pipes. Remember that it’s not structural, so you cannot nail anything into it, plus pests and insects are able to tunnel through it. This type of insulation is air-tight, so you may need fresh-air ventilation in order to meet building and safety codes.
- Polyisocyanurate structural insulated panels – Creating a moisture barrier, this foil-based insulation is on the pricey side. It should also not be used anywhere there is a moisture barrier.
- Fiberglass Insulation – Consisting of very fine glass fibers, fiberglass insulation has a paper face on top and is sold in bags or rolls giving it a fluffy appearance.
What Do You Need to Insulate Your Garage
While we can offer recommendations of the type of insulation you should use as well as how to install it, you will still need to figure out how much of the material you will need for your garage. here are a few guidelines that will help you to determine the type or quantity you will need of each material.
- Fiberglass insulation – To determine how much fiberglass insulation you will need, measure the distance around the entire garage and then multiply it by the height of the garage to determine the square footage. Always buy an extra unit of insulation in case you make a mistake, and, if you don’t use it, just return it.
- Garage door insulation kit – It is highly recommended that you use a kit when insulating your garage door.
- Expanding foam – If you see cracks or gaps in your garage walls, you will need to fill the gaps and cracks in to ensure that the cold or hot temperature won’t get inside. The expanding foam is available in either high or low expanding foam, which you should use will depend on how large the gaps and cracks are in the garage wall.
- Drywall – Use the same measuring process and then purchase the same amount of drywall as the insulation requires.
- Long sleeves and gloves – Fiberglass is well known for irritating your skin, so it is suggested to wear clothing and gloves for protection.

Tools You Will Need
- Sharp utility knife – You will need this to cut the insulation.
- Wood – Wood will be used as a guide to making it easier when cutting the insulation down to the right size.
- Staple gun – A staple gun will be used to staple your insulation into place.
How to Insulate a Garage Wall
Step 1: Clear out the Garage Walls
- Remove any drywall that already exists. You may want to rent a dumpster if there is a lot for easy trash removal.
- Clean up any dirt and also clean out the stud cavities.
- Check around for any mold and also clean up any chemicals that you may have in the garage like fertilizer or gasoline.
Step 2: Look for Cracks and Gaps in the Wall
- Fill any gaps or cracks that you find about 50% full as the foam will continue to expand and fill up space. It will have hardened completely in about eight hours.
Step 3: Install the Fiberglass Insulation
- First, staple the insulation’s paper face to the stud’s side and not the stud’s face. Make sure you leave the stud’s face exposed in order to install the drywall on top of the insulation.
- Use a piece of wood on top of the insulation as a guide in order to cut the insulation to the correct size. Then use a utility knife to cut away the excess insulation so that it will fit the size of the stud.
- Next, tuck the insulation in making it easier to staple. Make sure that the insulation all the way down on the side of the stud.
Step 4: Cover the Insulation with Drywall
- Screw and then glue the drywall to the stud without leaving the insulation paper exposed, which is a fire hazard.
How to Insulate Your Garage Ceiling
Insulating your garage ceiling will involve the same process as when you are insulating the garage walls. Make sure that you use insulation that is thicker R-40. Also remember to measure the width and height between the ceiling’s framing and cut the pieces beforehand, which will help when you are up on the ladder. Just remember to use thicker R-40 insulation.
The ceiling is the most important part of the garage to insulate since heat tends to rise up and then escape through the garage roof. It’s similar to when you wear a hat in the wintertime, so make sure that you protect the ceiling of your garage in order to keep the heat trapped inside. Make sure to check the reviews for the latest energy-efficient heater options in the market.
How to Insulate a Garage Door

When you insulate your garage door, remember that it can be more involved than when you insulate the ceiling and the walls. Your easiest option is to purchase a door that is already insulated. But, if you want to cut down on your costs and do it on your own, you can buy a garage door insulation kit, which has a process similar to when you insulated the ceiling and the walls.
Just remember that when you insulate the garage door, you will be adding weight to it. So, it may be necessary to change the door’s springs to retain balance and tensions so that it stays closed correctly. For this reason, it is often easies to hire a professional or to buy an already insulated door.
FAQs
How can I insulate my garage cheaply?
Garage insulation is a task you can do on your own. First, you need to choose a cheap type of insulation that will work with the climate you are in and the garage construction. Look for affordable R-value insulation like fiberglass roll and cellulose. Fiberglass is easy to unroll and install on horizontal surfaces as well as on vertical surfaces in a garage that hasn’t been completely constructed. Recycled loose-fill insulation, cellulose insulation can be blown into attics and walls, it is a good choice for a garage that has been finished.
Does insulating a garage make a difference?
Insulating your garage has a lot of benefits and will definitely make a difference in the temperature of your garage as well as provide safety precautions. Insulating your garage can eliminate uncomfortable temperatures when you walk out to your garage and allow you to store temperature-sensitive tools and paint. It will also improve your hobby space in your garage while decreasing noise from your neighbors and cars on the street.
If you own a classic car, an insulated garage will allow you to combat rust and better maintain your prized possession. Insulation is also good safety protection providing a layer in your walls that can protect cables and wires from damage by rodents. It can also provide significant fire protection and prevent carbon monoxide from coming through your walls and into your living area.
What is the best way to insulate a garage?
The best way to insulate your garage is to make sure that the ceiling, walls, and garage door are all insulated. Not only will this help maintain a consistent temperature, but it can also create a sound barrier from noise out on the street. The best type of insulation to use is either foam board, blanket batts and rolls, spray foam insulation, or blown-in insulation.
How much does it cost to insulate your garage?
The cost to insulate a garage will vary based on how large the garage is and the type of insulation you need to buy. The cost to insulate a garage can range from $0.50 to $1.25 a square foot, which means that insulating a two-car garage can cost between $338 and $845.