Why insulate your attic?
Attic insulation can reduce energy costs; however, the money you will save depends on your and your family's personal habits. It also depends on the type of property you own and other factors; such as the windows and doors and the type of heating you have. In general, you can save up to 50 percent of energy costs when properly insulated.
If you posses an unfinished attic and only use it for storage, you may opt to solely insulate the floors, directly above the rooms you inhabit. However, if your attic already has insulation, then you may want to insulate over the old insulation that has compressed over the years and no longer as affective as it once was.
Insulating your attic by rolling batts throughout is a generally simple project that is affordable and easy to perform. Onces insulation has been installed, you want to make sure you try not to store anything on top of it as it will compress the insulation making it less efficient.
How to install attic insulation?
Batt or roll insulation:
1) Lay unfaced batts or rolls between joists. Cut them only when necessary. Butt pieces together tightly. A one inch gap can reduce R-value by 20%.
2) Slide insulation under wiring (if possible), take care not to disturb connections. Cut to fit snugly around cross braces.
3) For second layer, install perpendicular to the first layer.