Can You Paint Over Radiant Barrier?

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Does the plain look of your radiant barrier bother you - so much so that you're thinking of having it painted to match the rest of your ceiling? In this article, we'll answer the question of whether you can paint over a radiant barrier. We've consulted the experts and here's what they say.

You shouldn't paint your radiant barrier because it will lose its inherent superior reflectivity. This characteristic is the main reason that it's able to block off up to 97% of the sun's heat from entering your homes. Painting it, even with Interior Radiation Control Coatings, will reduce its effectiveness in preventing heat gain.

Keep on reading so we can explain further why painting your radiant barrier is a bad idea. We'll also answer which way radiant barriers should face upon installation, if they can damage your roof shingles, if they can block cellphone signals, and whether they would still work in winter. Let's get started!

Picture of steel roof structure inside the house With a thermal insulation sheet for heat resistance of roofCan You Paint Over Radiant Barrier?

Can a radiant barrier be painted on?

Inside gable and joist view of ongoing project, insulation of attic with fiberglass cold barrier and reflective heat barrier between the attic joists

Some homeowners might have the idea to have radiant barriers painted so that they'll match the color of their attic. However, experts discourage you from doing this and we'll tell you why.

Radiant barriers work by reflecting radiant heat back to its source. They don't absorb the heat. They prevent it all together from getting inside our homes. And for them to do that, they have to have a highly reflective surface.

Painting their surface, even with a metallic or silver coating, will reduce their effectiveness. These coats are referred to as Interior Radiation Control Coatings or IRCC. The best performing IRCC can only reflect up to 75% of the heat, allowing 25% to enter our homes.

This would mean more heat gain. The warmer the house gets, the more your cooling system has to work to get the temperature to your desired level. This translates to more energy consumption and increases in electricity bills. This is why it's not recommended to paint radiant barriers. They are already very effective the way they are.

And while we're at it, it would also help a lot if you keep the surface of your radiant barriers clean and free of dust. Unwanted particles will only block the reflective surface and reduce their ability to prevent heat from gaining access to your homes.

What are radiant barriers made of?

Insulating of attic with fiberglass cold barrier and reflective heat barrier used as baffle between the attic joists to increase the ventilation to reduce humidification

Radiant barriers are used to block the heat coming from the sun. They are usually installed on the attic or underside of the roof because this is the part of the house that primarily covers it from the sun's rays.

The exterior of these sheets is made of a highly reflective material usually in the form of aluminum foil. Other layers beneath it can be made of plastic film, cardboard, kraft paper, or fiber-reinforced materials to help make it more durable and flexible. The reflectivity of its skin is very crucial in its effectiveness in blocking off radiant heat, which is the heat coming from the sun.

As it is, radiant barriers have a reflectivity of 90% to 97%. This means that they are able to prevent most of the heat from entering our homes through our roofs. Only 3% to 10% of the heat can pass through and add to the heat gain in the interior.

As such, the cooling system doesn't have to work very hard to keep the temperature inside the house at a comfortable level for its dwellers. Consequently, the energy consumption is lower and you'll see the reduced costs on your electricity bill.

Which way should radiant barrier face?

Radiant barrier, as the name implies, blocks radiant heat. This kind of heat is from the sun and the part of the house that is most exposed to the sun's heat is our roof. That is why radiant barriers are installed right at the underside of the roof so that they can block off this radiant heat.

When it comes to installation, there is a proper way of putting this barrier in place to optimize its usefulness. Experts say that the foil-side of the radiant barriers should be facing down or towards the interior side of the room. They should be positioned beneath the roof sheathing with at least three-quarters of an inch of air space in between.

This can be confusing since these reflective barriers are said to block the heat coming from the sun. Shouldn't they be positioned the other way around where they are directly facing the heat source? And by facing down, wouldn't they just reflect the heat back to the inside of the house making it warmer?
The answer to this lies in the fact that radiant barriers do not keep our homes cool by reflecting heat. Rather, they do this so effectively by not emitting heat.
Radiant barriers, being reflective materials, neither radiate nor emit heat. In principle, there is an inverse relationship between the material's reflectivity and its emissivity.
Since radiant barriers can reflect 90% to 97% of heat, they only emit 3% to 10% of the heat that falls on them. That's why there's minimal heat gain when you use these materials.
The air space is needed to create a vacuum where radiant heat is reflected. When there's no gap between the barrier and the roof, the metal sheet of the radiant barrier will act as a heat conductor instead. Heat will flow into your home and contribute to increased heat gain. Then, your cooling system will have to work harder to keep the temperature within the desired level which defeats the whole purpose of the barrier.

Do radiant barriers damage shingles?

Close-up on damaged asphalt shingles over the roof of a shed in the backyard

Shingles are materials that are placed at the base of the roof to give it additional protection from the elements. Since they are located near the radiant barriers, some homeowners are concerned that the reflected heat from the barriers would shorten their life expectancy.
Experts say that radiant barriers do not affect the lifespan of shingles. They won't damage them. This is because both materials do not absorb radiant heat. They both reject it.
As the radiant barriers reflect 90% to 97% of the heat, the roof shingles emit 90% of the heat out of the roof.
They do this continuously throughout the day that even at the hottest period, there's only a 5% heat increase on the shingles' surface which isn't enough to cause it any harm. They are built to fight off heat and withstand extreme temperatures.

Does radiant barrier block cellphone signal?

Close-up on damaged asphalt shingles over the roof of a shed in the backyard

One of the most common concerns regarding the use of radiant barriers is that it can interfere with the signal reception of cellular phones. Of course, this becomes a problem if ever it's true because no one will be able to reach you through your cellphone when you're at home.

This is rooted in the fact that metals block off radio wave signals. These signals are used in communication technology so that you can make and receive calls and messages wherever you are. But if there's something blocking these signals, then other people won't be able to contact you and vice versa.

According to experts, radiant barriers don't have a significant effect on your home's signal reception. Even though they are made of metal sheets, the foils aren't thick enough to really block off the radio wave signals.

These heat barriers are only about 3 to 5 mils thick which is the unit of measurement used to indicate a thousandth of an inch.

Also, radiant barriers are installed on your roof which makes up about 20% to 35% of your home's surface area. This means that even if the metal sheets would ever be thick enough, radio wave signals will still be able to pass through the walls and other portions of your house that aren't made of metal.

Besides, your cellphone most likely comes with a strengthened antenna that can overcome blockage of signal reception so it's very unlikely that your communication device will be affected by radiant barrier installation.

Do radiant barriers work in the winter?

Winter snow walk woman walking away in snowy forest on woods trail outdoor lifestyle active people.

Radiant barriers are primarily used to block off radiant heat coming from the sun and prevent it from entering the house and increasing the temperature inside. As such, these heat barriers are usually recommended during summer when the sun's heat can become intolerable.

But it doesn't mean that radiant barriers are only useful during hot weather. Homeowners can still benefit from its ability to reflect heat back to its source. As the heat rises and is about to flow out of the house, the reflective surface of the radiant barrier will bounce off the heat back into the interior side of the house.

Together with your roof insulation, minimal heat is allowed to escape. This means your heating system at home won't have to work extra hard to keep you warm and toasty inside.

Final Thoughts

It's simple: do not paint your radiant barriers so that you can optimize their effectivity in reflecting heat. Paint will only reduce their reflectivity and therefore, their ability to block much of the heat coming from the sun.

If you want to read about foil insulation, you may visit the following links:

Can You Paint Foil Insulation [And How To]

What Is The Best Attic Insulation For Texas?

 

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