From the installers: All About Roofing in Surprise, Arizona - Time Lapse Footage of Roofers Installing RoofingFoil™ by AtticFoil Radiant Barrier for Tile Roof in Paradise Valley, Arizona.

From the installers: In this episode we install [Roofingfoil™] radiant barrier underlayment. This is a Miami-Dade approved underlayment that also reflects radiant heat. It will require battens to be nailed down to create an air space between the metal roofing and the radiant barrier. So far in very unofficial testing, this drops the temperature on the underside of the sheathing from around 112 deg F down to around 102 deg F with an ambient temp average of 94 deg F.

From the installers: In this episode we install the garage roof panels. It was great to get the underlayment and battens covered. On average it [is] about a 20 degree drop in the underside of the sheathing. For ambient air temps around 96 the underside of the sheathing was around 120 degrees and with the radiant barrier this dropped to around 100 degrees. Adding the metal panels with a 5/8 in air gap still shows temps around 100 degrees regardless of the amount of sun we get in a day.