How to Insulate a Detached Garage

A detached garage is perfect for storing your car, tools, and other treasures. It might be tempting just to put up some insulation yourself, but before you do anything else, make sure you have a professional come out and inspect the building for any structural issues first. 

But if you want to use it for any of these things in the winter, you will have a cold time with it. The building or buying an insulated garage door will keep out the cold air so that you can work comfortably this winter. Read on for more information about how to insulate a detached garage door!

How to Insulate a Detached Garage

10 Reasons Why You Should Insulate a Detached Garage:

1. The foundation of a home is constantly under attack from cool and warm weather, moisture, and humidity.

2. A detached garage is open to the elements 24 hours a day compared to the 20 hours (at most) that an attached garage is exposed, meaning it can be as much as 40% colder in winter and 10% cooler in summer.

3. A well-insulated home is more energy-efficient and less expensive to heat, cool, and light. The insulation you choose can improve the safety of your home by reducing the risk of fire from a faulty electrical appliance or system.

4. Improves safety for occupants against noises from outside such as traffic, people talking or shouting, or barking dogs.

5. Improved comfort for the house’s occupants, who are not subject to drafts from an unconditioned garage.

6. A well-insulated garage will protect your home’s interior and belongings against extreme outdoor temperatures and humidity that can lead to costly damage such as cracking of wood, warping of floorboards, or mold build-up that can damage the home.

7. A well-insulated garage provides better protection against moisture, which is an enemy to wood and other materials like concrete or drywall. It also reduces the risk of condensation forming on cold surfaces when warm air comes in contact with them.

8. The cost of installing insulation in a detached garage is a one-time expense in most cases that can pay for itself many times over by reducing your utility bills.

9. Many insulation materials can potentially add value to a home when it comes time to sell it.

10. In cold climates, particular care should be taken to ensure the roof of a detached garage is well insulated as radiant heat can rise through the ceiling and cause problems inside.

Tools Needed:

You’ll need several tools for the job, many of which probably already exist. Of course, other tools could be used to do the job, but these are probably the most accessible and most efficient for this project.

  • Corded drill
  • Utility knife with snap-off blades
  • Razorblade / box cutter
  • Table saw or circular saw
  • Tape Measure 1 or 2
  • Permanent marker to mark lines/measurements

Steps to Follow: How to Insulate a Detached Garage

A well-insulated garage is not only a valuable investment for your home’s comfort, safety, and overall value, but it’s also a great way to provide additional storage space to help you manage clutter and protect possessions from the elements.

The steps required to insulate a detached garage will vary depending on the materials used to build it and the climate where you live, but a few fundamental principles apply to most cases.

A Well-insulated Garage 
Is a Valuable Investment

Step 1: Plan Your Project

Careful planning is essential for success when insulating a detached garage because all insulation projects start with an air-tight seal. Ensure all windows and doors are sealed shut before you begin insulating the garage and check for gaps near cracks and vents.

Step 2: Install Insulation

Installing insulation is a step that will vary depending on your project and the materials used to construct your detached garage. For example, some garages may require wall studs and drywall, while others will only need to install insulation within the walls.

Step 3: Install Vapor Barrier

Once you have finished insulating your garage, installing a vapor barrier is an essential last step. It will help to protect any insulation or other items from damage due to moisture and keep it dry throughout the year. If you are going to be using a vapor barrier for this project, be sure to check its size and materials carefully. For example, a vapor barrier made of polyethylene sheets is recommended for most garages, but it will not stop the spread of mold or moisture on concrete walls.

Step 4: Clean Up

Once you have finished insulating your garage, cleaning up the area and disposing of any debris properly is essential. Insulation can lead to unpleasant odors or pests like rodents and insects that will only add to your problems if left in place. Dispose of all debris safely to avoid future issues with bugs and other pests.

Step 5: Enjoy Your New Space!

Once you have finished insulation, your detached garage will be more comfortable, safer for vehicles and equipment, and far less likely to accumulate water damage over the years. Overall, a great step toward better home value that provides more storage space while lowering energy expenses.

Precautions and Safety Measures:

Before starting how to insulate a detached garage project, be sure to take the necessary precautions and safety measures first.

1. Turn off all power sources to avoid electrical shock or other accidents. Unplug appliances, switch off circuit breakers, disconnect light fixtures, etc. These steps are especially crucial if you plan to remove existing insulation and old wiring in your garage.

2. Open exterior doors and windows to allow fresh air in. Be sure to leave this area open for ventilation after the insulation is complete, and it might take several hours to a day for the fumes from spray foam or fiberglass insulation (if that’s what you’re using) to dissipate completely. If there are any fumes, you’ll start to see a burning sensation in your eyes and throat.

3. Wear gloves, goggles/safety glasses, and other protective gear when handling fiberglass insulation: Fiberglass is made of very small glass fibers that can irritate your skin and cause cuts and scratches if you’re not careful. It’s best to wear long sleeves, jeans/trousers, and gloves when handling fiberglass insulation.

4. Be sure to have a fire extinguisher or garden hose ready in case of any small fires caused by electrical shorts or sparks from metal tools used while working on the garage insulation project.

5. Remember to ventilate the garage when working with spray foam insulation.

Pros and Cons of Insulating Garage:


  1. It can help keep the internal temperature at a constant and comfortable level, which can help save money on heating.  
  2. If well insulated, the garage will remain warmer in winter and cooler in summer, reducing both condensation and moisture problems.
  3. An insulated garage can be kept warmer in winter, cooler in summer, and more comfortable all year round.


  1. Factory-made insulation materials may not suit a garage as they can swell and harden when heat exposure.
  2. Some insulation materials may produce dangerous fumes, which may cause harm to the structure and its contents.  
  3. Insulation materials can significantly increase humidity levels in both summer and winter, causing mold and rot problems if such problems already exist or dew problems in summer.
Some Insulation Materials May 
Produce Dangerous Fumes

4. The application of insulation can dramatically increase the humidity levels, which can cause further structural problems if there are any present.


Insulation is a good way to keep your detached garage warmer in the winter and cooler in the summer. It also helps with energy efficiency, saving you money on utility bills over time. Many types of insulation will work well for your detached garage, but there are some factors to consider before deciding what insulation to use.

In general, more expensive materials tend to be better at insulating than less expensive ones; this isn’t always true, so make sure you do enough research! You should also consider how much heat or cool air from outside might pass through the walls during different seasons.

For example, if warm air inside your house can escape out an open window, you should consider insulating the walls of your detached garage. We hope these step-by-step instructions on insulating a detached garage article will help you make an informed decision about insulation for your detached garage walls.

Jennifer Branett
We will be happy to hear your thoughts

Leave a reply

DIY Quickly