Anyone here familiar with radiant barrier insulation

[RU482]

We're experiencing our first warm sunny days of the season. Our 80 yr old house just isn't up to snuff when it comes to attic ventilation or insulation. In fact, I think there is only about 3.5in of blown in fiberglass in the ceiling.

So, I started doing some research, and the first things that pop up are radiant barriers. Basically a foil laminated thin insulator that you buy in rolls and tak to the underside of your rafters. They claim it blocks 97% of the radiated heat.

here is an example vendor

Just curious if anyone has used this material, and what you r experiences are

thanks

 

[flamingelephant]

The stuff works ok where insulation isn't a practical option, but you would likely benefit from just adding more fibreglass or cellulose blow in and adequate ventilation. The foil stuff is good for retaining radiant heat, but not that good at conductive/convective heat transfer prevention. Its technical R-value is like 3-4.... 3.5" of more insulation would be about R12. The foil is also very expensive per square foot compared to insulation.
So, add more insulation and ventilate your attic to 1 square foot of ventilation for every 300 square feet of home (with 1/3 of the ventilation being either from the soffits or low in the attic or 1/3 being exhaust venting for the top of the roof or top of the gables)
PM for more info if needed