During a storm, glazing is one of the first parts of a building exposed to risk: differential pressure, flying debris, branches and hail. The question of which protection to install comes up frequently, with two approaches often presented as alternatives: exterior protection on one side and safety film applied to existing glazing on the other. These solutions address different mechanisms and are not mutually exclusive.
What safety film actually does in high winds and impacts
Safety film is a polyester adhesive applied directly to the inside face of the glazing. Its primary role is fragment retention: if the glass breaks, the film holds the fragments together and limits their dispersal into the room. This mechanism reduces the risk of injury to occupants, but it does not make the glazing impact-proof or inherently resistant to wind.
Film performance depends on several factors:
- Film thickness: this varies across product ranges and intended applications. The specification must reflect the site conditions and the conclusions of the site assessment.
- Perimeter anchorage: a film simply applied to the glazing surface may detach under extreme wind pressure, particularly around the edges. Mechanical perimeter anchorage can help improve the integrity of the assembly, depending on the installation conditions and glazing type.
- Type of glazing substrate: toughened glass breaks into small fragments, while laminated glass remains cohesive even without film. The glazing type determines the film's value and performance.
What shutters and exterior protection do
Exterior protection—including hinged shutters, roller shutters and hurricane shutters—works through a different mechanism: it reduces the glazing's direct exposure to wind forces and flying debris. When properly specified, anchored to the load-bearing structure and certified to the applicable standards, it creates a physical barrier against impacts.
The main limitation of shutters is deployment: they must be put in place before the weather event, require regular maintenance and are effective only if properly closed when the storm hits. Installing them on older buildings or façades with complex architectural features may also be difficult or impossible.
Complementary solutions, not competing ones
Safety film and shutters do not address the same risk scenarios. Shutters protect intact glazing from pressure and flying debris. Film takes over if the glazing breaks despite the exterior protection, or in buildings without shutters.
The suitability of a combined approach—exterior protection plus retention film—depends on the site assessment and the applicable framework, including regulatory zoning, design wind speeds, the building classification and the project owner's requirements. This choice cannot be generalised and must be assessed on a case-by-case basis.
Practical decision criteria
Before selecting a solution, assess several parameters:
- Exposure level: geographical area, façade orientation and height, and weather history
- Existing glazing type: single glazing, double glazing, laminated or toughened glass—each configuration requires a different recommendation
- Occupancy: in public-access buildings, hotels and other occupied premises, retaining glass fragments is a priority safety criterion
- Architectural constraints: whether exterior protection can be installed
- Installation lead time: film installation time varies according to the glazed area, glazing type, accessibility and site conditions
For commercial projects, validation by a design office or approved installer remains essential. The performance stated in product data sheets relates to standardised test conditions and cannot be extrapolated without assessing the specific context.
What safety film cannot do
The limits of a film solution must be clearly understood. Even when anchored around the perimeter, safety film does not turn ordinary glazing into impact-resistant glazing as defined by EN 356. Anti-burglary or impact certification applies to a glass-and-film assembly tested in a laboratory under a defined protocol. Adding film to untested existing glazing does not automatically give it a certified classification.
For projects requiring certified protection against extreme winds or hurricane pressures, the selected solution must be defined by the specifications and the applicable standards. Purpose-designed laminated glazing may meet these requirements, subject to the findings of the risk assessment.
For more information about installation, read the complete guide to installing safety film on glazing and explore the Solar Screen range of safety films for glazing.