Weather-stripping is used to seal air leaks at any opening in the house that moves -- doors, windows, and traps. If you need to be convinced of the necessity of doing a good job of weather-stripping, check out Air Barriers in the search tab above -- or look at your last heating bill.
Much of the weather-stripping on store shelves is useless
There are a variety of weather-stripping products available at hardware stores, and some of it is rather useless. If a weather-stripping material won't last more than a year it's probably working poorly for most of the winter anyway, and you're wasting your time and money. I don't discuss every kind of weather-stripping and every application, but rather give some guidelines to help you make choices at the store.
The effect of climate on the quality of weather-stripping
One of the discouraging things for me was to discover that the choice you have at the store is dependent upon the climate you live in. The same companies make different qualities of weather-stripping. They stock the good stuff in the colder cities and the cheap stuff in Vancouver, Toronto and Montreal. Actually I am sure they would rather sell the better stuff and make more money, but apparently homeowners in milder climates just don't take weather-stripping seriously.
So it becomes a vicious circle: you don't buy it, you can't get it; you can't get it, you don't know it exists; you don't use it, you don't know what you are missing. So if you are going to be traveling through a colder part of the country, stock up on weather-stripping.
The secret source: glass repair shops
The good news is that quality weatherstripping, in a far wider variety than at the renovation centres, is usually available from glass repair businesses. They have to fix windows, so they stock the quality weatherstripping replacement pieces. Take a piece of your old weatherstripping with you, or bring in the window if possible to get the best match or substitute. Simply look up "Glass Repair" in the Yellow Pages.
For much more about weather-stripping, follow this link.