How Does a Radiant Barrier Work?

Reflect on this cool home insulation feature

A worker is putting a sealant on the vapor barrier joints.
Photo: natali_mis / Adobe Stock
A worker is putting a sealant on the vapor barrier joints.
Photo: natali_mis / Adobe Stock
Highlights

  • Radiant barriers are made of reflective materials like aluminum that redirect sunlight.

  • They can reduce cooling needs by 6% to 16% but don’t offer heat retention.

  • Radiant barriers are best for homes in hot climates.

  • They cost $1,700 on average and last 80 to 100 years.

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If you’re deep into researching insulation types for attics or elsewhere, odds are you’ve come across radiant barriers. While a radiant barrier isn’t enough to insulate your home all on its own, it can offer some extra protection from hot days. That’s why radiant barriers are so popular in particularly hot climates, like the southern United States.

But how does a radiant barrier work, and is it right for your abode? Understanding the mechanism behind these energy-saving solutions will help you make an informed choice. 

What Is a Radiant Barrier?

A radiant barrier is an additional insulation measure, often paired with another, more intensive solution, that limits how much heat is absorbed into your home. It’s available in two types—foil and spray-on—both of which work to keep your domain cool despite high exterior temperatures. While it can be a good choice for those across the country, residents of especially hot climates will experience the biggest benefits. 

How Do Radiant Barriers Work?

a worker in a vest and cap is fixing the vapor barrier on the ceiling
Photo: juraj / Adobe Stock

Anyone who’s ever stood in the sun on a hot summer day knows just how quickly things can heat up, and that rule applies to houses, too. Radiant heat, or a type of heat that travels in a straight line and is absorbed by solid entities, is the reason for this. Without any protective measures in place, it will continuously be absorbed into a home the longer it goes unmitigated. 

Radiant barriers offer some relief from this phenomenon because they’re composed of reflective materials, applied on top of traditional insulation, and installed just underneath roof panels in order to redirect sunlight and its punishing heat.

There are a few problems with radiant barriers to keep in mind—namely, that they become less effective when dusty and won’t work at all if they aren’t installed properly. If they aren’t placed facing an open airspace, you might as well forget about installing them in the first place. 

Fortunately, there are ways to minimize dust build-up, like installing radiant barriers aluminum-side down (though you can always opt for a double-faced option for extra protection). Radiant barrier installation is fairly straightforward, especially if you hire an attic insulation pro near you.

Do I Need a Radiant Barrier? 

Radiant barriers are a worthwhile purchase for those living in places where the sun shines year-round because of their cooling properties. Experts estimate they can reduce cooling loads by anywhere from 6% to 16% during hot seasons.

However, if your local climate experiences a lot of cold and snow, spending extra on radiant barriers is unlikely to recoup the same amount in energy costs. Plus, there are still ways to regulate heat absorption that may make more sense depending on where you live—like installing additional thermal regulation, which will also be effective when it is cold.

Frequently Asked Questions

The cost to install a radiant barrier ranges from $700 to $2,800, depending on the size of your roof and the type you choose. Most people pay an average of $1,700 to install a radiant barrier. Foil options, both single- and double-sided, cost between $0.10 and $0.90 per square foot, while spray-on options start at $0.60 and go all the way up to $1 per square foot—which can add up quickly.

When installed correctly, radiant barriers can have a life span of anywhere from 80 to 100 years—which, in some cases, is more than certain roofs. While most homeowners who have them installed don’t start to notice any issues for one or several decades, you can ensure no problems pop up by semi-regularly removing dust from reflective sides.

It is possible to install a radiant barrier yourself. However, knowing how to install a radiant barrier and actually doing it are two totally different things. For example, it’s important that they be installed in a straight line but at an angle that creates a gap between the roof panels and the foil or spray. If this gap is too large or small, it won’t function as it should, and that may be hard to avoid if you’re only a novice. When in doubt, leave this job to a pro.

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