Installing insulation batts and rolls in attics is quite easy, but doing it right is very important. Here are some rules of thumb –

• New Construction Insulation -  the vapor barrier facing should be installed with the facing placed down toward the ceiling gypsum board, except in hot humid climates where unfaced batts should be used.
• Older Homes Insulation – when reinsulating over existing insulation, it is recommended that unfaced batts be used. If there is not any insulation in your attic, fit the insulation between the joists. If the existing insulation is near or above the top of the joists, it is a good idea to place the new batts perpendicular to the old ones because that will help to cover the tops of the joists themselves and reduce heat loss or gain through the frame. Also, be sure to insulate the trap or access door. Although the area of the door is small, an uninsulated attic door will reduce energy savings substantially.