When it is time to insulate the home, start with the attic. To insulate the attic, first measure the size and spacing of the roof rafters. Consider adding batt insulation by first trimming the insulation to the measured sizes, and applying to the underside of the roof by pressing it into the cavities. For the amount and type of insulation needed, use the Home Energy Saver tool on the U.S. Department of Energy's website.
Before insulating an old home, without tearing down any walls, determine what type of current insulation exists and the thickness of any current insulation. To insulate the walls of an old home, first remove two courses of siding, one a quarter way up from the wall and a second just below the ceiling, from each story of the home. Find a wall stud, and mark the center between two studs, which is considered the middle of the stud bay. Many homes have sheathing underneath the siding. Drill a hole big enough to fit a hose nozzle using a spade bit drill in this sheathing.
Be certain that you are in the middle of an empty stud bay; and, measure 16 inches on each side all along the wall, which marks the center of each stud bay. Drill one hole on the top of the course of siding and one on the bottom of each stud bay center. Using a hopper filled with insulation, fill the lower drilled hole with insulation. When the machine starts to whine, that wall portion is full. Repeat with the hole drilled on top, and continue down the wall to fill all the stud bays. Cover the holes with adhesive backed flashing tape, and nail the siding back onto the walls.