Page "Roof" Paragraph 46

Forms of insulation are felt or plastic sheeting, sometimes with a reflective surface, installed directly below the tiles or other material ; synthetic foam batting laid above the ceiling and recycled paper products and other such materials that can be inserted or sprayed into roof cavities.

So called Cool roofs are becoming increasingly popular, and in some cases are mandated by local codes.

Cool roofs are defined as roofs with both high reflectivity and high thermal emittance.