The upgrade to NBS may not legally require that glazing be upgraded, but many building owners and facilities managers are now realising a moral obligation or duty of care to protect building occupants (and also persons outside of the building envelope) in the case of multi-story buildings.
Excerpts from Dr. T. C. Hutchinson’s (University of California – San Diego) 2009 Study on Seismic Effects.
Even a moderate amount of film (2 mil) suppresses damage to the window system and greatly assists with retaining the glass itself, thereby reducing the potential for the safety hazard of glass fallout.
When there is no film applied to the glass, the effects of extensive cracking cause on average 74% of the glass to fallout (range of 20%). With only minimal film application (2mil), less than 1% of glass is observed to fall from the specimen. Increased film thickness (4 and 2-ply 8 mil) increases the level of containment further to less than 0.75% glass fallout.
These numbers mirror our own in-house testing for glass retention, and in the Christchurch earthquake, buildings with glazing retrofitted with GlassProtech Safety and Security film performed as expected, even when the buildings had major structural failures. In some cases entire window frames were destroyed and shaken from the building, yet the glazing was retained by the film.