What this covers
A radiant barrier is a sheet of reflective foil fastened under the roof, usually to the underside of the rafters or the roof deck, facing an air space. It reflects radiant heat from a sun-heated roof instead of letting it soak into the attic. It works best in hot climates and in attics with ducts or equipment. The installer staples the foil smoothly across the rafters with the reflective side facing the air gap, keeps it clear of the soffit and ridge vents, and works around electrical and HVAC equipment. It is not a substitute for insulation on the attic floor; the two work together.
When to call
- A very hot attic in summer, especially with ducts or an air handler in it.
- Upstairs rooms that stay warm long after the sun goes down.
- A roof replacement or attic project where the rafters are easy to reach.
What to expect
- AssessThe installer checks the attic ventilation, framing and existing insulation.
- PlanThe foil layout and attachment method are chosen for the rafters or deck.
- InstallFoil is stapled across the rafters with the shiny side facing an air gap and vents left clear.
- CheckSeams, edges and clearances around vents and equipment are checked.
Get a certified company
Look up a certified company by ZIP code. Every company's license, insurance and trades are verified before it is listed, and placement is never paid.
Questions people ask
Is a radiant barrier the same as insulation?
No. Insulation slows heat moving through materials; a radiant barrier reflects radiant heat from the roof. Most houses that use one still need attic floor insulation.
Does it help in cold climates?
It mainly reduces summer heat gain, so it does the most in hot, sunny climates. In cold climates, air sealing and insulation usually come first.
Does dust affect it?
Dust on the reflective surface reduces how well it works. That is one reason foil is usually fastened to the rafters facing down rather than laid on top of the insulation.
Related: Attic insulation · Roof ventilation · Ductwork installation and repair · All insulation and energy
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