Part II: Conservation FirstChapter 3. Seal, Insulate, and Cover

Bubble-Wrap and Film Window Tricks

Temporary plastic layers for a winter, including where they help and where they look worse than they work.

Difficulty: Beginner
Cost: Under $20

published

Plastic on a window is a one-winter experiment. It can cut the draft and add a thin air layer. It will not match a sealed acrylic storm panel, and it will not match a quilt at night. It is worth doing when the sash is awful, the budget is a few dollars, and you are willing to take it off in the spring.

Two versions get confused. Bubble wrap clings to the glass. The bubbles are a small trapped layer right on the pane, the view becomes a shower door, and the gain is modest. Shrink film sticks to the stop, stands off the glass, and makes a still air gap across the whole sash. The film version usually works better and looks better if you get it taut. Both are interior. Neither replaces exterior shade in summer.

Difficulty

Level: Beginner
Time: An hour for several windows
Skills: Washing glass and using a hair dryer without roasting the trim

Cost estimate

Under $20

A film kit covering several windows, or a roll of large-bubble wrap and tape, usually lands here. Large custom windows can use the whole budget on one opening.

Materials

Item	Qty	Notes
Shrink-film kit	1	Double-sided tape and a film you tighten with a dryer. Prefer this over wrap when you can.
Large-bubble wrap	Optional	For a basement pane where the view does not matter. Bubbles toward the glass.
Scissors and a dryer	1	Low heat. The tape and the film, not the glass, are what you are warming.

Shrink film

Wash the stop. The tape will not hold on dust and grease. Apply the tape to the face of the stop or the trim, in a closed rectangle, not to the glass. Press the film on, leaving it loose. Warm it with a dryer until it tightens. Stop when it is clear and flat. More heat melts a hole and can soften vinyl trim.

The gap should be real, on the order of the depth of the stop, not a film glued to the pane. A hole or an untaped side leaves the draft in place. Keep the film out of the path of curtains that will snag it, and away from any heater.

You cannot open the sash until spring unless you remove the film. Do not put it on a window you need for ventilation or for egress. A bedroom exit is not a film project.

Bubble wrap

Cut the wrap larger than the glass and wet the glass with plain water. Press the bubbles against the glass so the flat side faces the room. The water holds it for a season in many houses. Tape the edges if it curls. It will look cloudy. That is the trade for a basement or a north pane you do not look through.

The thermal benefit is a set of small air pockets plus a reduction in the air washing the glass. Treat it as a comfort patch. Do not enter it in a payback spreadsheet as if it were a new window. Take it off in spring so the sash can dry and so you are not baking plastic against the glass in July.

Film on the stop makes a gap across the sash. Wrap on the glass is a smaller, cloudier layer.

Where this is the wrong tool

A window you open, a window that is your exit, a south window whose winter sun you want undistorted, and any sash that is already wet and rotten. Fix the rot and consider a real storm panel. Plastic over a failed sash hides the failure.

Condensation can increase on the outer pane if the film is the tightest layer. Look in the first cold week. If the stool is soaked, take the film off and weatherstrip the sash instead.

Skip egress and skip sashes you must open
Film is for fixed winter use.
Prefer film on the stop
Tape a closed rectangle, then shrink it taut. Stop before you scorch the trim.
Use wrap only where the view is already lost
Bubbles to the glass, water to hold it, off again in spring.
Check for water, then remove it when heating season ends
A summer of plastic is uglier and less useful than a winter of plastic.

Difficulty

Cost estimate

Materials

Shrink film

Bubble wrap

Where this is the wrong tool

Skip egress and skip sashes you must open

Prefer film on the stop

Use wrap only where the view is already lost

Check for water, then remove it when heating season ends

Further reading