Do I need a vapor barrier in my garage walls?

Author: Delia Gutkowski  |  Last update: Monday, April 7, 2025

The primary function of a vapor barrier is moisture control. In the garage, like other spaces in the home, condensation results from moisture in the air. Excess condensation and humidity levels in your garage can damage your garage's foundation and cause tools, vehicles, and cabinets to rust faster.

Can drywall be used in an unheated garage?

Yes. The biggest thing to worry about is moisture, not heat. If there are large swings in temperature, moisture could form inside your walls and form mold or rot.

Should an unheated garage be insulated?

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.

Do you need a vapor barrier on concrete walls?

It is best to place vapor barriers on foundation walls in basements before installing posts and doing primary insulation. Installing a moisture barrier will help keep moisture in the basement and prevent it from seeping into the walls and floors, leaving no room for mold.

Can you leave insulation exposed in a garage?

Exposed insulation can cause a variety of problems that can significantly impact your health and comfort. The level of risk depends on the type of exposure, the duration of the exposure and the location of the exposed insulation in your home. Exposed insulation in basements, attics and garages is the most common.

Vapor Barriers: Need one or not?

Can insulation sit on concrete?

Rigid Foam Boards: These are commonly used for concrete slabs due to their high insulating value and resistance to moisture. Spray Foam: Provides excellent air sealing and can be applied directly to the slab.

Where is most heat loss in a garage?

Heat loss can occur through air leaks in windows, doors and walls. Warm air can also leave through materials like glass or uninsulated walls or doors. Common areas for air leaks and heat loss in the garage include the following: Walls: A lot of garages have uninsulated walls.

Should I use a vapor barrier in my garage walls?

The primary function of a vapor barrier is moisture control. In the garage, like other spaces in the home, condensation results from moisture in the air. Excess condensation and humidity levels in your garage can damage your garage's foundation and cause tools, vehicles, and cabinets to rust faster.

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.

What happens if you don't have a vapor barrier?

“For minor projects, the absence of a vapor barrier leads to water intrusion, leading to an unstable foundation or a cracked slab.” The American Society for Testing and Materials (ASTM) outlines national standards for underslab vapor barriers.

Should I use faced or unfaced insulation in my garage?

Faced insulation is also a good idea if you are putting in first time insulation. Perhaps you've liked the warmth and energy protection of an installed insulated garage door and want even more insulation. If you're already adding insulation over existing insulation, faced insulation isn't necessary or suggested.

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.

What is the best insulation for garage walls?

We recommend using fiberglass insulation, since this type is easier to handle and can be used throughout the entire garage, including the walls, floors and ceiling. If you plan to use a different type of insulation, we suggest hiring a professional, since other materials can require more experience.

What is the best wall covering for an unheated garage?

Plywood, MDF, or OSB is the best material for building garage walls because it is both inexpensive and easy to work with. They may be attached to the studs with frame screws and, unlike drywall, don't necessitate any finishing touches.

Do I need a permit to drywall my garage?

You'll likely need a permit since this project may require soil grading to avoid drainage issues. Repairing your floor may be more cost-efficient than replacing it if grading is necessary. No permit may be required to hang drywall on exposed wooden wall studs in your garage.

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. Insulation can trap moisture in the garage, especially in humid climates, creating a perfect environment for mildew growth.

How do I know if I need a vapor barrier?

If you live in a mixed climate – hot and humid with several heating months in the winter, you probably need a vapor retarder. Specifically, if you live in climate zones 4C (marine), 5, 6, 7 and 8. Not sure your climate zone? You can check here.

Can I use plastic sheeting as a vapor barrier?

For crawl space projecs that require a vapor barrier installed within walls, builders commonly use a thinner plastic sheeting option such as 6 mil, but for the best durability in the crawl space, our vapor barrier experts instead recommend choosing 8 mil plastic sheeting.

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 thick is a garage vapor barrier?

Vapor barrier thicknesses range from 6 mils to 20 mils. 6 mil is the minimum for moisture control, with 20 mils being the most sturdy and puncture-resistant. The ideal thickness of a moisture barrier depends on how prone the area is to dampness. For dry areas, a 6-11 mil is standard.

Can you drywall a garage without insulation?

No 'need' to insulate it, the drywall should be fine over large temperature swings. If it's a detatched garage that you'll never heat, then don't bother. If it's an attached garage, then insulate as it's cheap and you'll benefit for decades.

Should you put a vapor barrier behind drywall?

Regardless of your environment, you should consider using a moisture barrier in basements and crawlspaces as well as beneath flooring and behind the drywall in high-moisture places like kitchens and bathrooms. It's better to be safe than sorry when moisture damage could put your home's structural integrity at risk.

How to keep a garage from getting so hot?

How to Keep Your Garage Cool This Summer: 11 Quick Tips
  1. Insulate your garage. Temperature regulation is key for a comfortable garage. ...
  2. Seal air leaks. ...
  3. Declutter your garage. ...
  4. Use reflective surfaces. ...
  5. Avoid heat-generating appliances. ...
  6. Let your car cool down before parking. ...
  7. Plant a tree. ...
  8. Shade the garage.

Where is the biggest heat loss in a house?

An estimated 25% of all heat loss occurs through the attic or roof of a home. Cracks or holes in an attic, along with improperly placed vents, allow for significant amounts of heat loss through the attic space. In addition, improper ventilation in attics leads to even more heat escaping.

What is the best heat source for a garage?

At the end of the day, it all depends on your needs. If you have a smaller garage that's well-insulated, then a propane heater or a combustion space heater would work well. If you're looking for a heated garage floor, then infrared heaters are the best option.

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