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Glass Breakage Investigation

Property type: Corporate Office Building

Location:  Lehi, UT

Client: Property Management Company

Incident description: The building was built in 2012. Three glass panes broke during 2013 and 2014. Then in 2015, 6 panes broke. This prompted the Property Management Company to reach out to Façade Consultants for guidance.

Injuries: None

Documents reviewed by Façade Consultants (FC): Site photos, Architectural drawing sheets, product brochures.

Site investigation by Façade Consultants: FC visited the site in 2016, four years after construction. FC took note of the various types of curtainwall and window conditions, some aspects of system weakness, surrounding geography and weather conditions, and catalogued prior instances of glass breakage.

These were the different glazing types:

  • Window wall at first floor – butt glazed at 4 sides – mullions toward interior
  • Unitized curtainwall at three floors of office – butt glazed at 4 sides – mullions toward interior and vertical fins at exterior
  • Unitized curtainwall at large activity room, butt glazed at 4 sides – mullions toward exterior
  • Field glazed, tall curtainwall at common area/food service, butt glazed at 4 sides – mullions toward interior, glass attached to mullions with patch fittings and dead load supports
Different glazing types.

Summary of Glass Breakage Cataloging Excercise

The glass breakage did not present a strong pattern. The strongest patterns were a) most glass was tempered, b) the first floor experienced most breaks and c) and most breaks occurred in 2015, when the building was three years old.

Broken Glass Evidence Available for Examination

There were only a few pictures and glass shards available for examination. For example:

This photo supplied by the client clearly shows tempered glass that has broken but in large part has stayed in place. This can happen at times. It affords the opportunity to closely examine the fracture origin for clues regarding the cause of breakage. Unfortunately there are no good images of the fracture origin and the Client did not know of the importance of preserving the fracture origin, so valuable evidence was lost.
This piece of heat strengthened glass yielded not much information about breakage causation.
Section of still-assembled tempered glass. From this we can see that the glass was well tempered, however the fracture origin was not within the sample, so the cause of the break could not be discerned.

The Local Weather

During the site inspection, FC noticed strong and variable winds at the site. A check of the local data confirmed this: During the inspection the wind came out of the north at about 6mph. One hour later the wind came from the south at 29mph. An examination of the local geography revealed that the site (and Lehi in general) is in a constriction between two parallel mountain ranges. Constrictions in air flow tend to accelerate the wind.

Arrangement of the Oquirrh and Wasatch mountain ranges creates a funnel, or constriction where winds will accelerate, right at the site.

The Building Amplifies the Wind

Rather than designing a building that might mitigate the effects of the wind, building designers went the other way. Dramatic architectural features such as overhangs, a tunnel, lots of corners and decorative fins stand right in the path of the wind, taking a beating daily.

Ornamental curtainwall fins are beautiful, but will buffeting of the wind eventually affect the glass?
Rubber gasket between ornamental fin and glass has come out. We found two such conditions. It is known that gaskets can shrink over time. Between the wind activity and potential gasket shrinkage, it is believed that more of this will occur. Whether the wind’s action on the glass can eventually cause more breakage is unknown.

Opinion of Façade Consultants: The absence of fracture origins has limited FC’s ability to provide a positive diagnosis of the causes of glass breakage. We have only background information and some theories. In the event of future breaks, better procedures need to be implemented. FC produced a 2-page questionnaire and instructions in the event of future breaks and recommends that the protocol be employed if more glass breakage occurs.

Disposition: Pending

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