Energy Star Attic Insulation 2 - Installation
Laying fiberglass rolls is an easy DIY job. If you have any type of insulation between the rafters, install the second layer over and perpendicular to the first. The second layer of roll insulation should be unfaced, with no vapor retarder. This will help cover the tops of the joists themselves and reduce heat loss or gain through the frame. Also, when laying down additional insulation, work from the perimeter toward the attic opening.
Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from can lights, unless they are rated ICAT (Insulated-Contact-Air-Tight). If you are using loose fill insulation, use sheet metal to create barriers around light fixtures or vents. If using fiberglass, wire mesh can be used to create a barrier.