To insulate a window for winter, clean the frame, stick double-sided tape around it, press a sheet of clear plastic film onto the tape and shrink it tight with a hair dryer. A kit costs roughly $20 to $50, and each window takes about 15 minutes, according to Family Handyman.
With the first cold nights arriving across much of the country, October is a good time to do it. The film adds a sealed layer of air against the glass and helps block drafts around old windows. Energy Trust, an Oregon energy-efficiency group, notes the method works best on single-pane windows that stay closed all season.
The film is a seasonal fix, not a replacement for caulking, weatherstripping or new windows. It comes off in spring. Pick a mild, dry day to work, since tape sticks best to clean, dry surfaces.
The job needs a few basic supplies. You will need a window insulation kit (film and double-sided tape), a hair dryer, scissors, a tape measure, a clean rag or microfibre cloth and isopropyl alcohol.
One safety note applies before you start. This is an indoor job on windows you can reach from the floor. Do not climb ladders or lean out of upper-storey windows to apply film. If a window is hard to reach, leave it or call a professional.
Step 1: Measure the window
Measure the height and width of each window from the outside edge of the trim, Family Handyman said. Most kits include one large sheet that you cut into several smaller coverings, so add up your measurements and check the kit covers them all before you buy.
Step 2: Clean the frame
Dust the frame with a dry microfibre cloth, then wipe the area where the tape will sit with isopropyl alcohol on a clean rag. Energy Trust advises cleaning the whole window and frame to remove dust, dirt and grease, then drying it completely. Tape needs a clean, dry surface to hold.
Step 3: Apply the double-sided tape
Stick the tape to the top, bottom and both sides of the window casing, pressing it down firmly. Leave the paper backing on for now. Some kits come with adhesive already applied to the top edge, so follow the instructions on your package.
Step 4: Cut and attach the film
Cut the film a little larger than the window. Family Handyman suggests adding two inches to the width, while Energy Trust says the sheet should extend two to five inches past the frame. Either way, leave extra material to trim later.
Start at the top left corner. Peel back about six inches of tape backing and let about an inch of film overlap the tape. Press the film across the top, then work down each side and across the bottom, peeling the backing as you go and keeping the film tight.
Step 5: Shrink the film
Set the hair dryer to high heat. Energy Trust recommends holding it about six inches from the plastic and moving it back and forth across the film. Family Handyman says to go around the taped edges first to help the film stick, then shrink the wrinkles across the whole sheet.
Keep the dryer moving rather than holding it in one spot.
Step 6: Trim the edges
Once the film is tight and smooth, cut away the excess around the perimeter with scissors or a utility knife. Run a finger along the tape to check there are no gaps, and press down any loose spots.
Repeat the process on each window. The film works best on windows you plan to keep closed all winter, so start with the draftiest ones.
Do not cover a window that serves as an emergency exit, such as a basement bedroom window. Check your local fire code or ask your fire department if you are unsure.
In spring, peel the film off slowly and remove any tape residue. Check the package instructions for how to do so without damaging paint or trim.
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Sources: Family Handyman, Energy Trust.
