Once again we are approaching winter. In many parts of the country flooding rains have occurred and in some areas snow already has fallen.

This is the time of the year when we begin to think about what we can do to cut costs and get the best bang for our heating buck. If you are like most Americans you already have insulated your attic and exterior walls. If you have not, it is time to do so. If you are a real smart consumer you also have insulated your floors. But, there still is more. Insulation alone will not do the trick. Another step, called infiltration control, should be undertaken.

Infiltration control refers to the containing of air leaks through penetrations in ceilings, walls and floors. It is critically important to a proper insulation job.

If you have a water faucet on an outside wall, chances are that it is connected to a pipe that supplies a plumbing fixture on the other side of the wall. Look outside the window in the kitchen, laundry or bath to see if this is the case. If the pipe protrudes from a wall cavity rather than from the rim of the floor, that pipe is in a prime location for an air leak. That's the opening on the outside. The hole on the inside normally will be at the wall behind a plumbing fixture (toilet, sink shower, etc.). The biggest air leaks usually can be found under cabinets. The holes in those places often are big.

Another place where infiltration occurs is in the attic where pipes in walls travel up through the roof. When this condition exists, air travels from the attic down into the wall cavity and out through the first hole it finds usually a wall switch or a plug. Plumbers and electricians are notorious for giving themselves plenty of room to work during the construction process. It is not uncommon to see a two-and-a-half-inch hole surrounding an inch-and-a-half pipe. Or a one-inch hole surrounding a three-eighths-inch wire. Actually, these are more than points of infiltration. They are small wind tunnels.

A heat-register inlet can be a the culprit if it is not sealed to the ceiling, wall or floor at its outside perimeter. More easily identifiable points of infiltration are gaps in exterior siding and window and door frames.

Years ago we often stuffed insulation into the gaps that air flowed through. That was because caulking wouldn't hold up in areas where there were very big gaps. We also used tin plates at the bottoms and back of cabinets where pipe penetrations were surrounded by large, gaping holes. We would cut a hole in the center of the plate that closely fit the size of the pipe. The overall size of the plate had to be large enough to cover the gap, with enough left over for fastening with screws or nails.

Caulking is still our recommendation for small gaps and tight joints. But for the big ones, all you'll need is a can of expanding foam sealant. No more tin plates or insulation that has a tendency to fall out. Simply spray on a little bit and right before your very eyes the sealant grows and grows and grows.

As with everything, foam has drawbacks. First, it is sticky beyond belief and almost impossible to clean up. Also, expandable foam sealant can cause things to bulge, bend and even break. So, be careful and patient. For example: when trying to fill the gap between a door frame and the house frame, one could easily cause the frame of the door to bulge by spraying too much sealant into the gap. Use a little at a time until you get used to the power that results when foam begins to expand. And last but not least, stick with one brand of foam sealant so that you can get used to the expansion. They all expand differently.