What Is a Radiant Barrier?

Radiant barriers are different than insulation in that they don’t slow down heat transfer; they stop it completely. Radiant Barrier Houston help mitigate energy costs, and a radiant barrier keeps your home cool without using your air conditioner as often.


When installing radiant barriers in a new home, they should be draped with the foil side between the rafters and trusses before the roof sheathing is applied. This application is called the rafter/truss installation.

What is a Radiant Barrier?

Radiant barriers are a type of insulation installed in the attic, primarily to reduce summer heat gain and cut cooling costs. They differ from conventional thermal insulation in that they primarily reflect radiant energy rather than absorb and retain it. All materials give off thermal radiation, and radiant barriers are designed to prevent it from passing through the roof deck and into the living space below.

Radiated barriers are not a replacement for conventional insulation, but they do significantly lower a home’s energy bills. They are typically supplemented with thermal insulation that slows down the transfer of heat through conduction and convection.

The radiant barrier’s effectiveness depends on its reflective properties, and the higher its reflectivity rating, the more energy it will reflect. Per Department of Energy regulations, a product classified as a radiant barrier must have a reflectivity rating of 90% or more and an emissivity rating of 10% or less. RadiantGUARD products have a reflectivity of 95%-97% and an emissivity of 3-5%, which is far better than the DOE minimum requirements for radiant barriers.

Another important characteristic of radiant barriers is moisture resistance. The presence of water vapor in an attic can cause significant damage to a structure and lead to mold growth, especially in cold climates. The moisture problem is mitigated by the use of perforated radiant barriers, which have small holes throughout the material to allow for air movement, and by regularly inspecting the attic to ensure that no condensation or water leaking has developed.

Radiant barriers also have a fire rating that is determined by ASTM E84 and the optional ASTM E2599 testing method. They must meet this standard to be considered compliant with the National Building Code.

Types of Radiant Barriers

Radiant barriers are available in a number of different forms. They are typically aluminum foil laminated to a substrate material like kraft paper, plastic films, cardboard or oriented strand board. Some are fiber-reinforced to increase strength and durability. Radiant barriers can be combined with thermal insulation materials in reflective insulation systems to act as the thermal insulation’s facing material.

When radiant barriers are used in conjunction with traditional attic insulation, they reduce summer heat gain and cut air conditioning bills by reducing the amount of energy needed to cool the house. They work by reflecting radiant heat instead of absorbing it, as conventional thermal insulation does. They don’t reduce heat conduction, however, because they are not as thick as the materials that insulators use to prevent conductive heat transfer.

A radiant barrier installed in a ventilated attic space alone will save five to ten percent of annual cooling costs in homes in warmer climate zones. The savings will be greater if the attic is already well-insulated, but even well-insulated homes can benefit from a radiant barrier.

The best radiant barriers have low emissivity ratings, meaning that they reflect heat instead of absorbing it. These barriers are typically manufactured from foil, but they can also be made of a variety of other material types such as coated fiberglass, cotton or cellulose. Radiant barriers are safe for use in the home because they don’t emit harmful chemicals or particulates. They are easy to install and can be a DIY project for the competent homeowner.

When installing radiant barriers, it is important to follow safety guidelines and use caution to avoid a serious accident or injury. Be sure to wear a long-sleeved shirt, pants, gloves and eye protection when working with tools. It’s also important to take frequent breaks and pace yourself, so you don’t become fatigued and make mistakes that could hurt your health or result in a poor-quality installation.

How Do Radiant Barriers Work?

Radiant barriers reflect up to 96% of radiant heat, reducing your energy costs and making your home more comfortable. They work by reflecting heat from the sun back to the air, helping your home retain its warmth in winter and keep it cooler in summer. The effectiveness of a radiant barrier depends on its emissivity, which is measured with a rating system from 0 to 1. Typically, a clean, unperforated radiant barrier has an emissivity of 0.03 to 0.05.

The emissivity of a radiant barrier is determined by the material and coating used to make it, as well as how the foil is installed. Radiant barriers are designed to be installed in vented attics of homes in warm climates, where cooling costs are higher. They can reduce cooling bills by 5% to 10%, depending on the climate zone and whether or not cooling ducts are located in the attic.

In addition to their ability to reflect radiant heat, radiant barriers help limit the transfer of heat from the roof to living spaces in a home through convection and conductive paths. They can be installed in combination with traditional attic insulation to create a nearly impenetrable envelope of insulating protection.

A significant amount of heat transfer into a home happens through the attic, where a roof’s shingles absorb solar radiation. By lining the attic with a radiant barrier, thermal resistance is greatly reduced, thereby lowering energy costs and increasing comfort.

Unlike insulation, radiant barriers are not harmed by humidity, which can lower the R-value of many insulating products. Also, unlike cellulose and fiberglass insulation, radiant barriers do not contain harmful chemicals that may irritate the eyes and skin. They are non-toxic and made of materials that are safe for use in homes with children or pets.

How Do Radiant Barriers Install?

Radiant barriers are installed in attics to prevent radiant energy from reaching air ducts and ceiling surfaces. They reflect heat rather than absorbing it, so your home feels cooler without using expensive energy to air condition it. Because of this, radiant barrier installations are often able to cut your cooling costs by five to ten percent. Radiant barriers also help reduce energy bills in cold climates by optimizing heating.

Several ways of installing radiant barriers exist, and the method used can depend on whether you are remodeling an existing home or building a new one. Certified attic specialists typically hang radiant barrier foil between the roof rafters during new construction and leave a two-inch strip of open space at the roof peak for ventilation. This method allows the attic to remain cool and provides for year-round energy savings.

Homeowners can also lay radiant barrier on the attic floor if they prefer not to install it between the rafters. This method can be susceptible to dust accumulation and requires careful planning to ensure that the air ducts are not covered. If you choose to do this, be sure that the ductwork is properly insulated and not leaking and that kitchen and bathroom vents and recessed light fixtures are not covered.

Another option is to drape the radiant barrier directly over existing attic insulation and staple it to the joists or rafters, or between the joists and the roof deck. Before starting to staple, be sure the attic is dry and that no moisture is seeping through any joints or around electrical junction boxes. As with any attic work, be sure to take proper safety precautions and use a partner whenever possible.

Which Radiant Barrier is Right for My Home?

The answer to this question depends on the specifics of each build. While there are some general recommendations, the best radiant barrier method for your build will vary based on climate, attic ventilation, construction stage, and the location of ducts and HVAC equipment in the attic. We have several different radiant barriers that you can choose from, each with its own benefits depending on your build.

Radiant barriers prevent radiant heat from passing through the attic to other parts of the house, and they redirect that heat into the attic space. This keeps the attic cooler, and it reduces cooling costs and comfort issues.

However, it’s important to note that radiant barriers do not replace insulation. They are designed to work in tandem with insulation, and they should always be installed under the attic floor and above any existing attic insulation. This is because the foil on radiant barriers will not function properly if it comes into contact with bare wiring, or if it becomes tangled in attic floor insulation.

Additionally, the airflow in an attic must be well-ventilated to keep attics cool and avoid a “hot spot.” If your attic isn’t well ventilated, or it has too many holes, radiant barriers will not effectively block heat flow from the roof to the living spaces of your home.

When used in conjunction with a properly sized attic, radiant barriers can lower attic temperatures by as much as 30 degrees and significantly reduce cooling costs. This means that your air conditioning system will have to run less, which will cut down on energy costs and extend the life of your unit. LP TechShield radiant barriers complement our portfolio of products that are proven to Defend Your Build, including LP Sheathing and Premium Sub-Flooring, as well as air and water barriers.