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The Guide to Radiant Barrier Roof Decks

Date: September 7, 2022

As a highly reflective material, radiant barriers either reflect or emit very little heat from the surface opposite the heat source, providing a permanent means of controlling radiant heat. Attic insulation and radiant barrier composite decking products are utilized in conjunction with each other as part of a home's overall energy efficiency plan.

You'll feel the heat radiate out of your ceiling and into your home when conduction takes over the radiant heat and conducts it through the insulation. To keep a radiant barrier from conducting heat, it must be separated from the heated surface by an air gap.

Radiant energy is unique in this debate because it is more sensitive to temperature differences than other heat flows. Radiant barriers decrease heat transfer by reflecting or releasing very little heat from their surface.

How radiant barriers work

A thermometer showing high temperatures
Heat transfer Method
RadiationRadiation transmission requires a vacuum or a transparent medium, which may be either a solid or a liquid.
ConvectionThis happens through air circulation in the house, i.e., open windows and other air spaces.
ConductionOccurs through the contact of different surfaces such as the components of your roof.
Heat cycle in a house

You need to know how a house loses and gains heat to know the function of a radiant barrier and if it is good for your home. The heat transfer rate between hot and cold areas depends on the temperature differential between the two areas.

Heat can be gained or lost by a house through different methods. All these depend on the media of heat transfer, but radiant heat does not require any media.

  • Conduction refers to the transfer of heat from one item to another through contact. A house's elements are always in contact as they are all fastened together and can therefore lose or absorb heat this way.
  • Convection occurs when heat moves through a fluid or gas. Convection causes the attic to be warmer than the lower house as warm air rises above the cold air.
  • Radiation transmits heat directly from one object to another with or without a medium such as air or glass. It's not reliant on fluid flow or even contacts; an example is the heat from the sun felt on your skin.

A radiant barrier, which is a thin layer of reflective material that functions as a mirror to reflect heat back into your home, can be used to make your home cooler in the winter and warmer in the summer.

A variety of studies have shown radiant barriers to have a significant influence on heating and cooling expenditures. Installing radiant barriers in the attic of a house is a common way to limit summer heat gain and save energy bills.

The barriers are made of a reflective substance that reflects it away instead of collecting heat. On the other hand, thermal insulation materials perform a better job of reducing heat transfer.

Attic temperatures can rise by as much as 30 degrees Fahrenheit thanks to conduction in the roofing materials. When a radiant barrier is installed, there is less heat transfer between the roof and other attic surfaces.

Convectional heat flow is slowed by conventional insulation materials but to a lower extent. By limiting radiant heat gain, radiant barriers and reflective insulation systems do their job.

Radiant barriers are most effective when they are positioned perpendicular to the path of the incoming radiation. The advantages of a radiant barrier are increased when the temperature differential between the two sides of the radiant barrier material is greater.

Attics with cooling air ducts are a good place to put radiant barriers in hot areas since they work better there than in cold climates. Using radiant barriers in a warm, sunny region can cut cooling expenses by 5-10%.

Types of Radiant Barriers

Radiant barriers can serve as the face material for thermal insulation in various configurations.

Aluminum foil is applied to one or both sides of a variety of substrate materials, including kraft paper, plastic films, cardboard, oriented strand board, and air infiltration. Fiber-reinforced materials are used to make goods that are more durable and easier to handle.

Take a look at these several options for residential roofing radiation barriers.

  • Sheathing

Aluminum foil is laminated to plywood to create a radiant barrier sheathing installed with the foil side facing the attic. This sort of radiant barrier is typically built as part of a larger project, such as a new building or a roof replacement.

  • Foil

A foil radiation barrier is put between the rafters of your attic, whereby a tiny gap separates the insulation and the attic's roof. This gap is important, as we discussed above, to avoid heat transfer through conduction.

Air is a poor conductor of heat, and the air gap serves to reduce significant heat transfer through conduction which is faster in metals. If other forms of insulation are installed, they also reduce heat transfer through conduction as they are poor thermal conductors.

  • Chips

Infused with silver, radiant barrier chips are blown on top of the current insulation layer into the attic. This is suitable for attics with a low pitch or that are otherwise difficult to reach for other methods.

  • Metal Roofing

Aluminum and zinc-coated metal roofing sheets that are stamped to look like traditional roofing shingles or tile are available for residential use. Radiant barrier plywood sheathing is commonly used in conjunction with this sort of roofing material.

Installation of radiant barriers

Using a licensed installer or following the right DIY steps is the best way to ensure that a radiant barrier is properly installed. For self-installation, be sure to read and follow all manufacturer instructions and safety precautions, as well as any applicable building or fire codes in your area.

When building a new home, radiant barriers are easier to add; however, if your old home has an open attic, you can still do so yourself. There are also installation instructions provided by the reflective insulation manufacturers that you should follow.

  • Installing radiant barriers can take some time, so plan to undertake it over the weekend with the help of a few friends or family members. Here are some suggestions to assist you in speeding up the radiant barrier installation and cutting down on the amount of manual effort required for the job.
  • When installing a foil-type barrier, there should be at least an inch of air space between the foil barrier's bottom edge and the roof's bottom edge. It is also possible to use oriented strand board or foil-faced plywood.
  • The attic may have exposed floor joists that could cause injury. Care should be taken.
  • You should begin your work in the early morning when the temperature in your attic is at its lowest. Make sure you always have a good supply of water on hand and drink it frequently, even if you don't feel thirsty.
  • Radiant barriers should not be installed directly on top of attic floor insulation because the foil is vulnerable to dust accumulation and may trap moisture in fiber insulation. Radiant barrier foil is often installed between the rafters of a new home's roof to prevent dust from settling on its reflective surfaces (double-faced radiant barriers are available).
  • Workers and households should be aware that reflective foil conducts electricity; thus, they should not come into touch with exposed electrical wiring.
  • To save time and energy, bring the radiant barrier and all your tools up to the attic.
  • DIYers should not expect to do a major project in a single day. Be patient and stagger the installation over a few days, preferably when it's not too hot outside.
  • If your attic is dim, you should bring a flashlight or another light source.
  • Having them in sight can help prevent accidents as you work with dangerous tools. The best place to establish a workstation is at a central location.
  1. Declutter the attic

The first step to installing a radiant barrier in an attic is to declutter it. Because attics are commonly used for storing things, you'll have to put in some effort to make it into a workplace for your creative endeavor.

Determine the length on one side of the roof and begin installation about 3 inches below the roof's apex. Install it to about 3 inches off the floor, then follow the roof's angle to the next step.

This method will make it easier to measure the radiant barrier and ensure that you're not wasting any of the material.

2. The radiant barrier can now be cut.

The first piece of the radiant barrier should be cut to the desired length with a utility knife.

Avoid stepping on or bunching up the radiant barrier when working with it, as these small bundles might diminish the sheet's length.

3. Keep the Top Stapled

Staple the radiant barrier to the rafters at a distance of 3 inches from the roof, as determined by the measurement you took earlier.

Staple your way through the attic.

4. To secure the bottom, use a staple gun.

Once the radiant barrier has been stapled to the top of the rafters, it should be slowly lowered to the bottom of the rafter to match the angle of the home. The bottom of the radiation barrier should be nailed down.

If the radiant barrier is cut too short or you run out, simply overlap the material by about 2 inches and staple it into the rafters. For best effects, consider adding a second coat.

Keep going until you find the wall plate by repeating these procedures (the vertical walls of the attic are typically located at the front and back of the home). To finish, go back and do it again on the other side.

You don't have to affix the material to the walls if you want to keep your house cool.

Installing on the Floor:

Instead of putting the material on the roof, put it down on the ground. However, this implies that you will no longer be able to use your attic as either a living or storage space.

All you have to do is a staple down the material after it has been laid over the insulation and floor joists. Make sure to remove any areas where ductwork or vents are present.

A radiant barrier may not be able to be properly installed in some attics due to the lack of space. In these circumstances, a radiant barrier should be installed on the roof and floor.

The radiation barrier should be installed about halfway down the roof—or, if you like, as low as possible. When you reach the point where the roof and floor meet, you'll begin laying the flooring section, starting at the end of the radiant barrier on the roof.

The pros and cons of radiant barrier

When compared to traditional insulation, radiant barrier insulation has some unique characteristics. New insulation methods like radiant barriers can significantly reduce utility costs for homeowners.

Insulation from the radiation barrier is not dependent on density like it is with fiberglass or cellulose. Instead, it's constructed from a reflective foil-like material that can either keep heat out or let it in.

The benefits and drawbacks of a radiant barrier are debatable. They include:

The pros of radiant barriers

  • It Prevents Radiant Heat
Thermometer and sun for The Guide to Radiant Barrier Roof Decks

Radiant heat, also known as radiant energy, is produced when the sun's rays strike a surface, such as a house. Most of the heat entering your house comes from these sources.

The term "radiant barrier insulation" describes this material's ability to block out radiant heat. The radiant heat that can penetrate other forms of insulation is blocked by radiant barrier insulation.

Similarly, insulation materials like fiberglass and cellulose inhibit heat transfer by conduction and convection.

  • It doesn't degrade with time.

It's possible that moisture, mold, and pests can swiftly damage other types of insulation. Insulation provided by radiant barriers does not degrade over time: radiant barrier insulation avoids the problem altogether.

  • They work well in hot climates.

Radiant barrier insulation is highly recommended for those who reside in warmer climates.

It improves the efficiency of your air conditioner, keeping your home comfortable even on the hottest days.

  • It doesn't attract mold.

In contrast to cellulose, this insulation is resistant to mold growth.

Radiant barrier insulation is resistant to mold and moisture, but cellulose and fiberglass are not.

  • They are not affected by humidity.

A radiant barrier's ability to deflect radiant heat means it can withstand high temperatures and humidity without damage.

Some radiant barriers feature perforations to let air through and keep moisture out.

Radiant barriers are useful for regulating heat since their performance is unaffected by humidity, unlike standard mass insulations.

  • They do not emit harmful substances.

Handling traditional insulation can irritate the skin, eyes, and lungs. Radiation shields don't give off lung-damaging particles (like fiberglass).

When dealing with insulation, it's best to play it safe and wear protective gear, including clothes, gloves, goggles, and a face mask, just in case.

  • They add the R-value of a roof.

Insulation goods and materials can be ranked by their R-value. The R-value of your roof is something you should consider if you want to ensure warm air stays in during the winter and cool air stays out during the summer.

Materials with higher R-values insulate better because they allow less air to pass through from the outside to the inside. An increase in thermal efficiency is achieved through radiant barriers, which increase the R-value.

Up to 97% of radiant heat can be deflected by reflective insulation. Insulation-like thermal resistance materials are typically positioned in the middle of a double-sided radiant barrier.

The R-value of conventional insulation degrades over time (the ability to stop or slow heat transfer from warm to cold). Radiant barriers, in contrast to more conventional insulation, never "settle," meaning their quality and/or R-value remain constant over time.

  • They complement existing insulation.

If you already have insulation in your attic or crawl space, a Radiant Barrier can be added on top of it. Additionally, radiant barriers can increase the R-value of insulation by varying amounts.

  • They are rodent and bird-proof.

Rodents and birds won't bother with radiant barriers because they usually contain inorganic materials.

  • They are versatile and can be used to insulate various parts of a home.

If you need to insulate ducts, hot water tanks, or pipelines, go no further than radiant barriers.

For surfaces to cool off, radiant heat must be reflected off of them.

The cons of radiant barriers

  • It is prone to dust and dirt build-up

Radiant barrier insulation is not susceptible to mold growth; however, it is susceptible to dust and dirt buildup. The buildup of dust, while not necessarily harmful, can diminish the effectiveness of radiant barrier insulation.

  • It loses some of its effectiveness in colder climates.

Radiant barrier insulation is a good choice for warmer climates because to its efficiency and effectiveness, but it may not be as useful in colder regions. Using thermal insulation in conjunction with radiant barrier insulation or thermal insulation on its own may be the best course of action if you reside in a cold climate or experience periods of abrupt cold weather.

In colder climates, radiant barriers might be more expensive than thermal insulation.

  • The problem with conductive heat gain is not addressed.

Radiant barrier insulation is great at blocking the sun's rays, but it will not be as good at blocking the heat from the air or the ground.

Because of this, installing thermal insulation in your home, especially in the attic, could be a good idea.

Frequently Asked Questions

Do you need insulation with radiant barriers?

You should still use mass insulation in addition to a radiant barrier. In addition to the radiant heat benefits, it also helps limit the passage of heat via conduction and convection, thus increasing the thermal efficiency of mass insulation.

Is DIY Radiant Barrier Installation Possible?

The project isn't that difficult to complete on your alone, but you'll need a lot of help to get it done—so you might need to call a few friends.
Having a local attic insulation company come out and conduct the job will save you a lot of time and effort.

About Mikku & Sons
Mikku and Sons red repair track with its logo painted on its side- roofing company track wraps
Our roofing company was founded in 2001 by Michael Riutta, who is still part of the ownership and management team. Between Michael, his two sons and co-owners, Devin and Joshua, and our crew members, we have many years of experience to handle any type of roof repair or roof installation solutions you may need.