Winterizing your windows

Last week, I went over to help winterize a friend's apartment. We started by sealing some drafts under the sink and installing a new threshold on the front door. Then came the windows.

In any home, windows are a major heat loser. Paul Fisette did a really good job of explaining windows and heat loss in an article on the Fine Homebuilding website, so I'll let you enjoy his piece rather than writing yet another explanation. Suffice to say, an insulated wall is always a better heat trap than even the best window. But we like sunlight, so what do we do?

Sensible homeowners with a bit of cash will get new windows. They pay themselves off in only a few years, thanks to savings on heating bills. But tenants can't do that.

Seal the leaks
Start by spraying a minimally expanding foam insulation into any big gaps around the window frame. It will expand to fill the space, but not so much that it'll buckle the window frame, as a regular expanding foam insulation might.

Then go outside and caulk any gaps or cracks around the window. Remove any old caulking and clean the area first. There are a few tips on caulking in the first post in my winterizing series.

Shrink-wrap the windows
Plastic film is a good way for tenants to cut heat loss through windows. Heat-shrinking films are cheap enough to pay for themselves in one winter, and will likely make a room more comfortable. Small kits start at about $5 at most hardware stores and will do one or two windows. Bigger kits exist for patio doors. The best option is to buy a roll of the film, which will likely cost $10-25, depending on the size, and will come with a few rolls of two-sided tape. It will do quite a few windows (we've done four so far and have plenty left).

How to properly install plastic film on windows
1. Clean the frames
Start by choosing an area on the frame that will allow a continuous cover. It may be on the metal or vinyl window frame, or even onto the wooden trim around it, depending on how the window was installed. I've done both with success.

Then clean the frame. Any dust will prevent the tape from sticking properly. Also, make sure you remove any toys or vases from the window sill. You'll feel mighty silly if you seal them in. I know. I've done it.

2. Heat it and tape it
Not all kits suggest heating the frame first, but it does seem to help. Use a blow dryer to warm the frame where you'll apply the tape.

Then start applying the tape. I suggest going across the top first, then down the sides and across the bottom. Start at one end, with the tape edge butting up to the tape or frame edge above it, then work your way across (or down), smoothing it with your finger and avoiding any ripples. Let the tape rest for a little while (some kits suggest 15 minutes, but I've done fine with less time).

Don't peel the backing off the tape until you're ready to put the plastic up.

3. Hang it
Rough cut a piece of plastic. Unroll enough that it will easily cover the window with a good inch or two on every side. On the rolls, the film is often folded in two, so unfold it before trying to hang it.

Next, peel off the backing on the tape. This should be easy to do, getting it started with a thumbnail or the tip of your knife.

Start by pressing one of the top corners into place. Then stretch the film across to the other top corner. Work your way down one side, then the other, gently pressing the film into place. As you go, try to get it taut, but don't worry about making it wrinkle free at this stage. Do avoid any major sagging or wrinkles on the taped edges themselves. After you've gone across the bottom, run your thumbs across the tape, all the way around the frame to ensure a good seal.

4. Heat-shrink your window
Starting in a top corner, use a hair dryer to shrink the film. You'll see the change. Work your way around the edges, until they're smooth. Then move toward the middle. You're done when the film is taut and smooth all over. If you've done a good job, then the film should barely be noticeable.

5. Cut to fit
Using a sharp knife, such as an Olfa knife, slice off the excess film. Go all the way around, and make sure the plastic is cut through. You don't want to have to tug at the ends to get them off, as this could undo your good work up to this point.

Handy Tip: I inevitably nick the plastic with my knife. This is bad. if it's off in a corner, or on a window that you don't tend to look out, the solution is easy. Cut off a piece of the two-sided tape and use it to cover the hole (as long as it's a tiny one). Heat it, wait a while, then come back and peel off the backing. It's a minimally visible repair that, in my experience, will hold for at least one year.

Now you've got a cozier home, and probably a lower heating bill as a result. Congratulations!