Enerflex Radiant Barrier roll is installed by stap-ling to the rafters. Best for new construction and covering the gable end walls and other vertical surfaces. Enerflex Radiant Barrier reduces heat transfer by thermal radiation across the air space between your roof and the attic floor, where insulation is typically installed. On a hot day, heat from the sun is absorbed by the roof shingles and warms up the sheathing below which radiates heat toward the attic floor and conventional insulation. All materials emit radiant heat to varying degrees based on their surface temperature. By installing Enerflex Radiant Barrier, up to 96% of this radiant energy will be reflected back toward the roof. Each roll is 48" W. x 12' L.