Is the R-value of 15.32 realistic?

Only with a proper air space on the reflective side, as in a rafter or furring-strip install. Stapled flat against a surface, the foam's own R-value is roughly 1 to 2, so treat 15.32 as a best case.

Can I use it on a garage door?

Yes. It is a common garage door application: cut panels to size and glue or tape them to the door's interior. Keep the door's moving parts and springs clear.

Does it work as a vapor barrier?

SmartSHIELD lists it as a vapor retarder. Foil-faced rolls block vapor when seams are taped, but foil also traps moisture, so face the barrier toward the warm, humid side and tape all joints.

How much area does one roll cover?

A 24-inch by 50-foot roll covers 100 square feet. Measure your rafters or door panels and add about 10 percent for cuts and overlaps.

SmartSHIELD rates it Class A and Class 1. Check your local code, since exposed foam in some occupancies needs a thermal barrier over it.

SmartSHIELD -5mm 24”X50ft Reflective Insulation Roll

Q: Where is the SmartSHIELD -5mm 24”X50ft Reflective Insulation Roll cheapest?

At Amazon, for $84.95, as of our latest check.

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Our take on the SmartSHIELD -5mm 24”X50ft Reflective Insulation Roll

SmartSHIELD's reflective insulation is a foam-core radiant barrier sold in a 24-inch by 50-foot roll. The foil faces reflect radiant heat while the closed-cell foam adds a small conductive barrier, and the roll also works as a vapor retarder and sound dampener. SmartSHIELD rates it Class A/Class 1 for fire and claims an R-value up to 15.32, though that figure depends on installation and air space. At $84.95 at Amazon as of November 4, 2026, it is the only new price listed, so there is no recent range to compare against.