Should I Use Plastic Window Film Inside or Outside?

Plastic window film is one of many energy-efficient means to help with both keeping a house cool in summer and warmer in winter. Most heat loss occurs around the windows. The air-tight gap, created by the use of fitted plastic, prevents drafts and condensation. However, the film cannot generally be used on most aluminum-framed windows because the gap between the frame and the glass is too small to work effectively.

Using Plastic Window Film

Plastic window film can be an inexpensive alternative to double-glazing windows. The film, which looks similar to cling film, is applied on the inside of the window. Putting the film on the outside would only expose it to weathering elements, so by putting it inside, it's better protected. Before putting up the plastic film, first take down any curtains, drapes or blinds so you can more easily reach the inside of the windows. Then clean the glass and frame, drying it thoroughly before applying the tape and film.

To help position the film, use double-sided tape. The tape should make a continuous square or rectangle around the window frame. Once the tape is securely in place, allow it to settle until the adhesive sets. Leave on the tape backing until you are ready to put on the plastic film.

The plastic will be cut and adhered to the window via the tape. You'll want a small overhang or excess all the way around to make sure you don't end up with gaps. Once the tape backing has been removed, smooth the plastic across the window. A good strategy is to adhere the plastic film across the top, anchoring it at the corners first. Next, smooth it across the top then work down the sides. Smooth it across the bottom last.

A hair dryer, set on high speed, is used to shrink the film against the window. A good strategy to ensure the film goes on tight and smoothly is to begin at one of the corners, then continue moving slowly across the film from there, making sure there are no wrinkles. If you touch the dryer to the film, the film may melt, requiring you to scrape off the mess and start over. Once finished, use a sharp pair of scissors or a razor to trim off the excess film.

The plastic window film, when properly installed, should help reduce heat loss through drafts. Because windows are a major source of heat loss, you might also wish to have heavy, lined drapes for the windows.