When to Use a Vapor Barrier With Insulation [Pro Guide]

January 24th, 2023 BY First American Roofing

Have you been dealing with unexplained drafts in your house? You may be dealing with an insulation problem!

Your insulation could be ineffective for a variety of reasons, including

The biggest culprit, though? Water damage.

If your insulation has any gaps in it, water can find a way in. Or, more specifically, water vapor. The good news? There is a solution.

A vapor barrier is an easy way to keep water out of your home and protect your insulation. But where should you install it? And what type is right for your house?

If you’re wondering when to use a vapor barrier with insulation, don’t worry. We’ve done the research for you so that you can start taking care of your home ASAP!

What Is a Vapor Barrier?

when to use a vapor barrier with insulation installing vapor barrier

So, what exactly is a vapor barrier?

A vapor barrier is a sheet that covers your insulation to stop water from causing moisture damage to your insulation. When water vapor gets into your insulation, it can cause a whole host of problems, including

A vapor barrier— also known as a vapor retarder— will help you avoid expensive repairs further down the road.

What Types of Buildings Need a Vapor Barrier?

Does your home need a vapor barrier?

Vapor barriers can be beneficial for a wide range of buildings, including both residential and commercial. For larger commercial properties, in particular, a vapor barrier could help you save on expensive energy costs for your larger properties.

What Climate Zones Need A Vapor Barrier?

Vapor barriers can be useful in all climate zones. However, if you live in a cold climate, a vapor barrier is absolutely essential. A vapor retarder will create an air seal that keeps the cold air out so that your home can maintain its internal temperature.

Additionally, homes in cold climates are particularly susceptible to condensation buildup, which can cause moisture damage to your insulation and surrounding walls. Condensation is formed when the external temperature of your home is vastly different from the interior. When the warm air cools? Bam! You’ve got a condensation problem.

By creating a moisture barrier, you can effectively protect your home and the existing insulation.

How Much Does it Cost to Install a Vapor Barrier?

Vapor barriers themselves are relatively inexpensive to purchase. Depending on what type of material you choose, it will only cost $2-$4 per square foot to install. However, you may find yourself with some extra costs if you are adding a vapor barrier to an existing room.

Not only will you have to budget to remove and replace drywall, but you should also factor in potential labor costs if you are planning to hire a professional to install it. As you install your vapor retarder, you may also discover that you need to replace worn-down sections of your insulation.

What Types of Vapor Barriers Are There?

When it comes to selecting what type of vapor barrier is right for you, you may feel overwhelmed by the many options available. Here are some of the more popular building materials on the market.

Vinyl Wallpaper

If you live in a mild climate, vinyl wallpaper may be a good option for your vapor barrier. These are installed inside of an exterior wall and work quite effectively at creating an air barrier for your insulation. That being said, this type of vapor barrier is not recommended for buildings located in hot climates.

Kraft Paper

Kraft paper is a popular type of vapor retarder. Kraft paper is pretty much exactly what it sounds like; a thin layer of brown paper that typically comes glued to the back of fiberglass batts.

Aluminum Foil

when to use a vapor barrier with insulation aluminum vapor barrier

While aluminum foil was originally used to help deflect heat away from the walls, it has since been discovered that it is quite an effective moisture barrier, as well. It’s also a very affordable option for homeowners on a budget.

Polyethylene Vapor Barrier

If you have a modern home, it’s likely that you have a polyethylene vapor barrier installed. this type of interior vapor barrier is the go-to for most homes these days due to the fact that it works as both a moisture barrier and an air barrier. For superior protection against outdoor air, as well as peace of mind, knowing that your home is protected from water damage, you can’t go wrong with a polyethylene vapor barrier.

Where Do I Need to Install a Vapor Barrier?

Vapor barriers are useful in various places in your home. In general, most homeowners prefer to install them as part of their roof deck, as well as on any exterior walls. Because these are the areas that are most susceptible to water vapor gathering, it’s important to make sure that they are protected.

A little extra moisture protection will go a long way when it comes to extending the life of your insulation. A professional vapor retarder installer should be able to help you choose the best places to install protection in your home.