Should an unheated attached garage be insulated?

Author: Dr. Mackenzie Dooley IV  |  Last update: Wednesday, July 16, 2025

If you're simply storing your car in the garage, which is the intended purpose, you don't need insulation. However, if you plan to use your garage like an extension of your home, as many homeowners do, adding insulation can definitely be a worthwhile upgrade.

Should you insulate the ceiling in an unheated garage?

During the winter, the floor may feel cold and uninviting, while in summer, the room might become uncomfortably warm. Without proper insulation in the garage ceiling, temperature extremes can seep into these living spaces, making them inconsistent and inefficient to heat or cool.

Is it worth insulating a non-heated garage?

Insulating a garage can lead to significant energy savings by maintaining stable temperatures, especially in attached garages where cold air can seep into nearby rooms, affecting your home's overall efficiency.

Will insulating an unheated garage cause mildew?

Insulating an unheated garage alone may not necessarily cause mildew, but the risk of mildew increases if there isn't proper ventilation.

Do I need vapor barrier in unheated garage?

The majority seem to agree that insulated, unheated garages, should be allowed to breathe. If the garage is heated, you will need a vapor barrier, otherwise you will get frost and mold.

Should I insulate my garage attic?

Should I insulate an unheated attached garage?

Do you really need to insulate a garage? If you're currently heating or cooling an uninsulated garage, insulation will make a major difference. However, if you don't plan to add supplemental heat or cooling to the garage space, adding insulation won't necessarily be much of an upgrade.

How do I keep moisture out of my unheated garage?

Five Ways to Reduce Condensation in A Garage
  1. 1 - Use climate control. Fundamentally, condensation happens when there's a lot of moisture in the air, and then that air becomes cool enough to lose that moisture. ...
  2. 2 - Use a dehumidifier. ...
  3. 3 - Install vapor barriers. ...
  4. 4 - Don't store wet vehicles in the garage.

When should you not use a vapor barrier?

Because a vapor barrier is a low permeable barrier, it keeps moisture from passing through. This is beneficial to keep moisture away from a dry surface but will trap moisture behind it if installed on a water-damaged concrete wall, causing the wall to fail further.

Why aren't garages insulated?

It can be expensive to insulate your garage, depending on its square foot—how much insulation you need (and where you need it). It's a really big, messy project—especially if you have to punch holes in existing drywall. If you DIY garage insulation, there's the risk of doing it incorrectly, causing long-term problems.

How much does it cost to insulate a 24x24 garage?

The cost to insulate a 24' x 24' garage is $3,000 - $8,000. Garage size influences the cost of insulation. The 24'x24' garage will house 2 cars and some extra space for other purposes. The average cost to insulate a 24x24' garage with spray foam is $6,000.

How do I keep my garage warm when it's unheated?

Freezing Cold Garage? Here Are 5 Tips to Keep it Warm
  1. Get Warm and Toasty With a Heater.
  2. Insulate the Garage Door.
  3. Insulate the Garage Walls.
  4. Repair Or Replace the Weatherstripping.
  5. Consider Caulking.

How to insulate a non-heated garage?

5. How to Insulate a Garage Ceiling
  1. Use thicker batt R-40 insulation.
  2. With a staple gun, install rafter vents on top of the rafters. ...
  3. Cut insulation to fit between the rafters and shove it into position with the paper side down.
  4. Repeat across entire ceiling and ensure there are no gaps or crevices when done.

Do I need an insulated garage door for a detached garage?

They are particularly advantageous for attached garages and garages used for activities beyond vehicle storage. On the other hand, non-insulated doors provide basic protection from the elements and may be a suitable option for detached garages or outbuildings where budget is a primary concern.

What is the cheapest way to insulate a garage ceiling?

As a homeowner, learning how to insulate a garage requires proper preparations and safety precautions. The cheapest way to insulate a garage is by using do it yourself spray foam insulation.

Does insulating a garage door make a difference?

Does Insulating a Garage Make a Difference in Temperature? Yes, insulating a garage door can make a significant difference by acting as a barrier between the outside and inside temperatures.

Can insulating a garage cause mildew?

Moisture issues.

Fiberglass and cellulose will retain moisture, which can lead to problems with not only mold and mildew, but wood rot as well. Solution: Update the insulation in your garage with a material that doesn't retain moisture.

What is the best insulation for an attached garage?

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 precut batts and long blankets that fit between wall studs and ceiling joists.

Do you need a vapor barrier when insulating garage walls?

Homes in areas with high humidity and occasional temperature drops will also experience garage condensation. Combining a vapor barrier with Comfortbatt® insulation will further improve moisture control in the space as it's water and moisture resistant. It does not absorb moisture to maintain its insulating value.

Should you put plastic over insulation in a ceiling?

Exposed insulation is at risk of catching fire if not covered properly because it is extremely flammable. Installing a fire retardant plastic sheeting over insulation slows the fire damage rate in the case of an adverse event.

Will mold grow under a vapor barrier?

However, if not installed correctly or if damaged, vapor barriers can actually contribute to mold growth.

Is Tyvek a vapor barrier?

Is DuPont Tyvek® a vapor barrier? No, DuPont Tyvek® is not a vapor barrier. It is made with unique material science to keep air and bulk water out while allowing moisture vapor inside walls to escape.

How do you keep an unheated garage warm?

If you want to keep your garage warm, installing a unit heater is a good idea. These appliances do not take up much space and are quite affordable. You can choose an electric or gas heater, and if you want a highly energy-efficient option, you can opt for a mini-split heat pump.

Why is my attached garage so humid?

This is because most garages aren't designed to regulate temperature like the rest of your house. On hot summer days, the humidity in your garage can hang in the air, and as temperatures cool, they stick to surfaces in the garage and can build up into the winter months.

Why is everything rusting in my garage?

Excess condensation and humidity levels in your garage have a negative affect on your home. They can damage your garage's foundation and cause tools, vehicles, and storage cabinets to rust faster.

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