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How to Add Reflective Mylar to the Windows to Keep Heat In

Gabriel Dockery

Mylar is a type of polyester film developed and trademarked by DuPont, and is available with a variety of coatings. Mylar with a metalized coating is useful as a window cover that helps keep heat in or out because of its reflective properties. Mylar film is strong, but can be tricky to work with. Mylar is inexpensive and commonly comes in sizes measuring several feet in each direction, for convenient application on any size window.

Install reflective Mylar on windows to increase heating efficiency.
  1. Measure the dimensions of the glass pane in the window.

  2. Cut the Mylar sheeting to the dimensions of the measured window pane, using scissors.

  3. Apply double-sided tape to the outside edges of the window pane.

  4. Slowly attach the top side of the cut Mylar sheet to the top side of window's double-sided tape. Proceed slowly to ensure no air is trapped, causing bubbles under the film. Place the "shiniest" side of the Mylar sheet so that it's facing in toward the room.

  5. Attach the Mylar to the sides and bottom of the window's taped edges.

  6. Repeat this process for other panes within the window.