Radiant barriers work by reflecting the heat coming through your roof on sunny summer days. Unlike fiberglass or cellulose insulation, radiant barriers do little to prevent the conduction of heat or cold through the air and have no R-value.
While not a substitute for traditional attic insulation, radiant barriers may reduce your air conditioning bill by 5% to 10% (according to the U.S. Department of Energy) if you live in a hot climate. Radiant barriers have little or no effect on winter cold air or heating bills.
Check out the basics of attics to learn how to keep your attic in tip-top shape.
Types of Radiant Barriers
There are several options for radiant barrier materials and installation methods — the ones you choose will depend on your climate and project scope.
Available radiant barrier types include:
- Reflective metal roofing
- Radiant roof sheathing
- Metal (aluminum) foil
Reflective metal roofing incorporates a radiant barrier into the roofing material, providing a clean exterior look without visible foil. It can be more expensive than traditional asphalt shingles or other common roofing materials.
Radiant roof sheathing has a reflective foil facing adhered to one side of structural roof deck material, combining the radiant barrier with roof decking. Radiant sheathing costs more than plain foil but can be easier to install during new construction.
Aluminum foil is the most common and cost-effective radiant barrier material. It’s available in rolls from home improvement stores for DIY projects. Make sure to use foil-backed tape to seal seams between sections.
Foil radiant barriers can be applied on top of rafters in new construction before installing the roof sheathing or on the underside of rafters on houses with an existing roof.
Installation Considerations
Proper installation is essential to get the full benefit of a radiant barrier. The reflective side must face down toward the attic space. Make sure to overlap and tape seams to prevent gaps.
For maximum effect, the radiant barrier should cover rafters, joists, and other framing in the attic space and completely cover gable ends and knee walls in the attic. Hot spots can develop if areas are left uncovered.
Don’t install a radiant foil barrier on top of attic insulation since condensation can form under it — even with perforated foil — resulting in moisture buildup. This moisture can reduce insulation effectiveness and cause damage like mold or rot.
Costs of Radiant Barriers
If you’re considering adding a radiant barrier, you’ll need to know the material and installation costs involved.
The material cost for a basic double-sided aluminum foil radiant barrier runs from $0.20 to $0.40 per square foot, so a typical 1,200-square-foot attic would require $240 to $480 worth of foil. Labor costs depend on difficulty of access to the attic and how complex it is to cover all attic framing. Expect professional installation fees of $200 to $600.
Radiant sheathing costs more per square foot than foil, ranging from $1.20 to over $2.00 per square foot. A reflective metal roof can cost $350 to $1,000 more than a typical asphalt shingle roof.
The most economical option is adding a radiant barrier when redoing an existing roof or during new construction. Installing under an existing roof is more complex and usually costs more in labor.
Effectiveness in Different Climates
While radiant barriers work well at reducing summer cooling costs in hot southern climates, they provide little benefit in northern areas with milder summers.
The Department of Energy estimates a radiant barrier can save 5% to 10% on cooling costs in the southern half of the United States. However, savings may be lower based on attic configuration, your insulation’s R-value, duct location, and other factors.
Radiant barriers have almost no impact on winter heating costs and energy savings, regardless of climate. They may not be cost-effective for homes that already have adequate attic insulation.
Additional Tips
- Make sure you have proper attic ventilation along with a radiant barrier. Good airflow allows heat buildup to escape to maximize the barrier’s effectiveness.
- Having a radiant barrier installed by trained professionals ensures proper placement.
- Do energy efficiency upgrades like air sealing and adding extra insulation before installing a radiant barrier. Your barrier will have the most significant impact combined with other improvements.
- Combining a radiant barrier with R-30 to R-60 attic insulation can help keep your attic cooler and reduce cooling costs in hot climates. Getting adequate attic insulation is vital.
So, Is Installing a Radiant Barrier Worth It?
When properly installed, radiant barriers can provide moderate cooling cost savings in hot southern climates, but depending on attic configuration, ductwork placement, and other factors, savings may be less than expected. Radiant barriers are not an effective retrofit for attics with adequate insulation in moderate northern climates.
If you choose to install a radiant barrier, get quotes from multiple contractors in your area. The ideal time to install is during new construction or a roof replacement project. This allows easier access for professional installation. Be sure to air-seal and upgrade attic insulation before deciding whether to invest in a barrier to maximize value.
Consider the costs and your climate before installing a radiant barrier — in an existing home with R-30 insulation, it may not pay for itself in energy savings.
FAQs About Radiant Barriers
How does a radiant barrier work?
Radiant barriers reflect infrared radiation (heat) rather than absorbing it. This reduces heat transfer into your home and lowers your air conditioning costs. They’re not effective at preventing conductive heat transfer through materials.
Does a radiant barrier act as insulation?
No. Radiant barriers have an R-value of zero and provide no insulation value. Insulation works by trapping air to resist conductive heat flow. Radiant barriers simply reflect radiant heat.
Do radiant barriers help with heating costs in cold climates?
No. Radiant barriers only redirect radiant heat, so they don’t give you any winter heating efficiency benefit. Their impact is only on summer cooling costs.
Can you install a radiant barrier on top of the existing attic insulation?
It’s not recommended. Condensation can form between the foil and insulation, reducing effectiveness. Radiant barriers should be installed above the attic floor with insulation on top.
How long do foil radiant barriers last?
Properly installed foil radiant barriers can last 20 years or longer. Ensure seams are taped and edges are secured so wind doesn’t rip the foil.
