Is It Better To Put Plastic On The Inside Or Outside Of Windows?

Is It Better To Put Plastic On The Inside Or Outside Of Windows?

Applying plastic film to windows is a cost-effective way to enhance insulation, reduce energy costs, and protect against the elements. The decision to apply plastic film on the inside or outside of the window depends on several factors, including the primary purpose of the film, the type of window, and environmental conditions. Let’s delve into the advantages and considerations of both approaches to help you determine the best option for your needs.

Applying Plastic Film Inside Windows

  • Solar Heat Reduction – For climates where cooling is a priority, applying reflective or sun-control plastic film on the exterior can help reduce solar heat gain, keeping interiors cooler and reducing air conditioning costs.
  • Direct Protection – Exterior film can offer direct protection for the window glass, shielding it from scratches and minor impacts.


  • Environmental Wear – Films applied outside are exposed to environmental conditions that can degrade the material over time, requiring more frequent replacement.
  • Installation Challenges – Exterior applications can be more challenging, especially for windows on upper floors, and may require special equipment or professional assistance.

Best Practices and Recommendations

  • Purpose and Climate – Consider the primary goal of applying plastic film. For thermal insulation and energy savings in colder climates, interior application is generally preferred. For solar control in warmer climates, exterior films designed for sun protection might be beneficial.
  • Film Type – Ensure the plastic film is suitable for your intended application. Some films are specifically designed for exterior use and are more durable against weather conditions.
  • Professional Advice – When in doubt, consulting with a professional can provide insights into the best type of film for your windows and whether interior or exterior applications would be more effective for your specific situation.

Whether to apply plastic film to the inside or outside of windows largely depends on your objectives, such as improving insulation or reducing solar heat, as well as practical considerations like ease of installation and durability against weather. By carefully weighing the advantages and considerations of each approach, you can choose the placement that best meets your needs, enhancing the comfort, protection, and energy efficiency of your space.