Before starting any home improvement project you should always think safety first. Thus you should wear proper clothing and gear for the job at hand. Starting with outside the house, search for places for air and water to enter your home from the outside. Do this by searching the exterior of the house from the roof to the foundation. The object is to prevent air and water from entering the house during the winter season.
First check the gutters for proper pitch and alignment. If they need cleaning after all leaves have fallen follow the recommendations of the article “Gutter Clearing.” While someone else is present check the roof for loose or missing shingles and flashing. If any is out of place replace or reseal it. You also should look at your chimney cap to see if it is in its proper place to prevent precipitation by the weather, besides nesting birds. If you are not sure about climbing up on the roof you could have it inspected by a professional. This will save you headaches and money in the long run. Also while you or the pro are on the ladder scan the eaves and soffit for holes possibly made by squirrels who intend on moving in for the winter. Before repairing any surface thoroughly clean it before hand. Seal all holes that are discovered. When using caulking use outdoor caulking, this is water proof and formulated for outdoor use.
The siding, if it is present, should be snug against the exterior walls of the house. There should be thin sheets of insulation behind the siding and against the walls. If the insulation is missing or damaged the purpose of the siding, to reflect and insulate, is virtually nonexistent. Use the outdoor caulking around the outer edges of the aluminum siding to seal it more efficiently. Check brick walls to see if they need tuck pointing. This should be done because air can seep in or out through such spaces.
Now observe the entire foundation of the house for standing water and spots or damage. Depending on your particular situation you could seal minor gaps of about one quarter inch space with tar. Make sure all downspouts drain water away from the foundation of the house. Also the soil at your foundation has to be angled downward and away from the house. Dryer openings, air conditioners and swimming pools should be covered. Swimming pools should also be drained and cleaned before winter. Kitchen vents can also be closed and covered. Next clean and install storm windows of doors and existing windows.
From the outside seal all perimeters and seams of doors with weather stripping and windows with caulking. Only seal the upper windows of double hung windows. The lower windows will be treated from inside the house. Do this when the temperature is optimum as is noted on the caulking tube. Make sure you use caulk around all door and window molding as well. Washing the windows just before the weather becomes too cold will allow more sun through during winter.
Now turn your attention toward the inside of the house. Clean all surfaces before weather-proofing them. Starting at the top again inspect the attic or crawl space for holes or gaps that allow light and thus air into the home. Seal gaps larger than one quarter inch with foam insulation. The kind sold by the can is all you need. Take note though that the foam takes some practice to apply it sufficiently without wasting it. This is because the foam continues to exude from the nozzle a minute or two after the pressing of the nozzle has stopped. So with this in mind stop pressing the nozzle some time before you finish a bead of foam. The foam will continue to expand a little while after you apply it some do not apply it liberally. Applying the foam conservatively is best. Also never apply the foam into gaps or holes around doors or windows. This is to be avoided because the foam will most likely expand and distort the present alignment of the parts causing them not to open and close properly or at all. Make sure your attic or crawl space has insulation and of the recommended R value. The R value is the rate at which a material reflects heat. Also make sure that the insulation is installed correctly. Fiberglass insulation should have a vapor barrier that should be against the underside of the roof when the insulation was or is to be put in place.
Next when you weather-proof down stairs insulate the bottom windows of double hung windows with weather-stripping where the windows slide along a channel. Close all, but one, storm windows. Remember to wash them. Also seal the gap where upper and lower windows meet when they are closed. It may be practical to leave one window in the house with its screen down and its storm window partly up to allow for fresh air during winter. Now install weather-stripping around the perimeter of all doors that lead directly to outdoors, this will include front and back doors on the main and basement floors and balconies. Added warmth can be provided from thick fabric wall hangings or tapestry. Carpet also increases the warmth of a home, but try environmentally safe floor coverings. Put up floor length draperies to help keep warmth in and the cold out.
If all of this your home will be much more warm this year than the last. One more word of advice, after the weather turns cold reassess your work and take note of what needs correcting. Redo what can be done and redo what cannot be done, during the winter, next spring. Until then, happy weatherizing to you.