The insulation layer around the house should completely surround the living spaces in the house. Take a look at the illustration at left. The pink lines indicate where the insulation should be placed. The amount of insulation will vary depending on the location of the house as well as the part of the house being insulated. The general rule of thumb for mild climates is R-11 in the walls and floors and R-19 in the attic. In moderate climates the optimum insulation will be R-19 in the walls and floors and R-30 in the attic. For cold climate living you will want R-19 in walls and under floors and a heavy blanket of R-38 to R-49 in the attic. As shown in the illustration, you will want to leave airspace above attic insulation to prevent damaging moisture being trapped.
Even new houses can often use another layer of insulation in the attic. Pink layers of fiberglass, purchased in batts or rolls are laid over existing insulation. Be careful of performing this operation, as there is often no flooring in the attic. You can lay 1-inch plywood where you intend to step to protect yourself from falling through the thin drywall. Don't forget to make sure the insulation stays away from recessed lights (at least 3 inches) and metal flues. When handling fiberglass, be sure to wear a face mask and gloves. Remember not to lay craft-faced (paper-backed) insulation in the attic. Exposed paper is considered a fire hazard.
There is also a new technology for attic insulation called a radiant barrier. Layers of a radiant film are separated by a nylon mesh. When laid down in the attic over your old insulation, it acts as a barrier to escaping heat. The great thing is, it will also act to reflect heat from the living part of the house in the summer.
Insulation in walls, if not adequate now, can be a major undertaking. Older homes, especially in the Pacific Northwest, were not well-insulated. Many were built with only a 1-inch sheathing over the frame. Professional contractors can blow in insulation by drilling holes in the siding (between studs), blowing in insulation, and then plugging the holes. If you wish to do this job yourself, you will need to rent a special pneumatic pump. Insulation can be purchased at lumber yards.
Next on your list of winter preps should be to have a plan for what you would do in a winter emergency.