Heatshield-R20  applied to underside of roof decking will reduce heat gain in your building & will lower the surface temperature of insulation making it more efficient in controlling heat gain. This is probable the best single area to use Heatshield-R20. Great USE for those left over paints When completed it should have an even appearance with very minimal shadowing of the roof decking we recommend that all rafters be coated and the upright supports coated about 1 foot down from roof decking,  as these all conduct and hold heat.Attics are very dry and absorbent and in most cases require two coats.