The difference between 4mil, 8mil, and 14mil security film is thickness, which directly determines how much force the filmed glass can withstand before an intruder gets through. 4mil provides basic shatter protection and slows entry by 15 to 30 seconds. 8mil is the standard for residential security and can delay entry by 1 to 3 minutes. 14mil is commercial-grade and can resist sustained attack for 3 to 5 minutes or more.
As a security film installer in the GTA, we install all three thicknesses depending on the property and the level of risk. Here is exactly what each one does and when to use it.
4mil Security Film
4mil is the entry-level security film. It holds glass together after impact, preventing shards from flying and creating a basic barrier. An intruder hitting a 4mil filmed window will crack the glass but find it still hanging in place instead of falling out. With sustained effort, they can push through relatively quickly.
Best for: Interior glass partitions, glass doors in offices, childproofing, storm debris protection, and properties where the primary concern is flying glass rather than forced entry.
Cost: $10 to $14 per square foot installed.
8mil Security Film
8mil is the most popular thickness for residential security in the GTA. It provides substantially more resistance than 4mil. An intruder hitting an 8mil filmed window will find that repeated strikes do not create a usable opening. The glass cracks but the thick film absorbs the energy and holds the panel together.
Best for: Residential homes concerned about break-ins, ground-floor windows, patio doors, basement windows, and small commercial storefronts.
Cost: $14 to $18 per square foot installed.
14mil Security Film
14mil is the heaviest option and is used where maximum protection is required. This film can resist sustained attack from blunt objects, providing the longest delay time of any film option. It is extremely difficult to breach quickly and is often paired with structural sealant (DOWSIL 995) for a complete anchored glazing system.
Best for: Commercial storefronts with high smash-and-grab risk, jewellery stores, cannabis dispensaries, banks, government buildings, schools, and residential properties in high-risk areas.
Cost: $18 to $22 per square foot installed.
Does Thickness Affect Visibility?
No. All three thicknesses are available in clear options that are virtually invisible once installed. You cannot tell the difference between 4mil and 14mil by looking at the glass. The only difference is performance under impact.
The Perimeter Seal Factor
Regardless of thickness, security film performs best when anchored to the window frame with structural sealant. Without anchoring, filmed glass can potentially be pushed out of the frame as one piece. With anchoring, the entire system holds together under attack. At Proferred Film Solutions, we recommend and install perimeter seals on all security film projects using DOWSIL 995 structural sealant.
Which Thickness Is Right for You?
For most GTA homeowners, 8mil is the right choice. It provides strong residential security at a reasonable price point. If you are a commercial property owner or have specific high-risk concerns, 14mil with a perimeter seal gives you the maximum protection available.
Call (833) 725-3456 for a free assessment. We will evaluate your property and recommend the right thickness for your situation.