Can I just roll the material out on the roof before reshingling?
This will not provide a radiant barrier. Remember, to be a radiant barrier, the aluminum foil must be installed facing an airspace. If there is no airspace, the foil acts as a conductor and quickly passes heat by conduction from a hot surface to a cooler one. If your re-roofing job requires decking replacement, however, it is a good time to consider a radiant barrier, especially the foil-faced roof sheathing materials on the market.
