Where should a radiant heat barrier be installed in the attic?

The radiant heat barrier should be installed on the rafters within the attic space. This placement is effective because it reflects radiant heat away from the living space below, reducing cooling costs in warmer months. By positioning the barrier on the rafters, it intercepts heat from the roof that would radiate down into the attic and then into the home. This arrangement maximizes the barrier's effectiveness.

In contrast, when a radiant barrier is installed on the ceiling, it would be too far down the thermal envelope to prevent heat buildup effectively. If placed between joists or on the attic floor, it would primarily address conductive heat transfer rather than reflecting radiant energy from the roof, which is the intended purpose of a radiant barrier. Thus, locating the barrier on the rafters is the optimal solution for enhancing energy efficiency in a structure.