Adding insulation to your attic floor is an effective way of reducing heat loss and energy consumption. It is advisable to have as much as 12 inches of insulation in an attic floor which equates to an R-38. This is an easy Saturday afternoon project that you can accomplish with a few tools and some personal protection like a face mask and gloves. Remove all the old insulation and install two new R-19 layers perpendicular to each other. Be sure not to block any air vents from the soffit and install air baffles to allow you to move the insulation up to the roof line. You will need to have 1 square foot of ventilation for every 150 square feet of roof area with this insulation thickness. This can be accomplished with soffit vents as well as roof louvers or a ridge vent.