Security window films are a great way to provide low-cost protection for glass windows and doors against a variety of threats and dangers.

Security window films are designed to hold shattered glass together under stress. Originally developed to lessen the damage of flying glass caused by an explosion, security window films have been repurposed to protect against forced entry, severe weather, and even active shooters.

Typical applications for security window films include:

  • Bomb blast mitigation
  • Forced entry prevention
  • Smash and grab crime prevention
  • Protection against windstorm and severe weather damage
  • Glass retention – Protects from falling glass caused by spontaneous glass failure
  • Glass Safety
Picture of 2 men installing security window films
3 men installing Security Window Films

Today, bomb blast mitigation and forced entry protection is the most common use of security window films.

How effective a particular security window film application will be is determined by four factors –

  1. The thickness of the film
  2. The type of glass
  3. The material and construction of the window frame
  4. Whether or not the film is attached or “anchored” to the frame.

Security Film Construction

Security window films are constructed of PET polyester and come in thicknesses ranging from 4mils in thickness up to roughly 24mil, with 8mil being the most common. They are typically clear, although tinted versions are available. The film is secured to the glass with a strong “pressure sensitive” (PS) adhesive.

As a rule, thicker films are stronger than thinner films. Thicker films have higher break strength, tear strength, and puncture strength. This is especially true for forced entry protection – thicker films provide a high level of protection than thinner films. This improved protection is reflected in longer delay times to penetrate the film.

Close up of a man installing security window films
Security Window FIlm Picture #4

Glass Type and How it works with Security Window Film

There are three common type of glass – annealed, tempered and laminated. For residential and commercial construction annealed glass and tempered glass is by far the most common. As far as security window film is concerned the biggest difference between the types of glass is how they break when struck by an object or force.

Annealed glass breaks into relatively large pieces, which helps hold the glass into the frame even without an anchoring system. Tempered glass breaks into small pieces. Security film applied to tempered glass can be easily broken out of the window frame unless it is properly anchored to the window frame.

Window Framing Systems

There are a wide variety of framing systems used to hold the window glass in place. Residential window frames tend to be made of vinyl or wood. From a security standpoint these are relatively weak materials and do not stand-up to a determined attack by an intruder. Commercial framing is typically made on aluminum and is much stronger.

The window framing system should also be wide enough to allow a window film anchoring system to be installed. Most residential window framing systems do not provide sufficient area for a proper anchoring system.

Security Window FIlm Picture #5
Security Window FIlm Picture #6

Window Film Attachment Systems

Window film attachment systems, also called anchoring systems, are designed to bond the applied security film to the window or door frame. When properly applied they transform the window, security film and window framing into a solid reinforced system. 

Attachment systems can massively improve the performance of security film applied to your glass. They hold the glass in the frame under repeated attack and massively increases the time it takes to get through a window with security film installed.

While there are a variety of window film attachment systems available the most common is the “Wet Glaze” anchoring system. Wet Glaze uses a structural sealant (typically DOW 995) to anchor the film to the frame.

Security window film versus Security Screens

Security window film does offer increased protection for glass windows and doors. It does hold shattered glass together and, when properly installed, offers a basic level of protection against intruders, severe weather, and glass hazards. Another advantage is that it is very affordable compared to other glazing security systems.

When you need a fast, effective, and affordable system to protect your glass doors and windows professionally installed security film is a good choice.


For higher levels of protection security window screens are the better choice. They give you all the benefits of security window film without the downsides. Our Crim Safe security screens are custom made to the exact size of your window opening, provide improved delay times and every window screen is secured to the structure of your building.

If you’d like more information on which option is best for your situation, contact Holdfast Security Screens. On of our technical experts will evaluate your needs, walk you through the options and help you decide which solution is best for you.