In this case, it’s not likely that an interior designer’s specification was at fault (the building was quite old and early reports suggest the wall was deteriorating), yet this highlights the potential liability interior designers could face.
In a scenario like this one, the specifying designer would be responsible for documenting these conditions. This includes accounting for the size and weight of the mirror, pre-existing wall condition, and any special mounting requirements.
It is the interior designer’s duty to document and communicate this information. They must coordinate with the contractor and vendor, and inform them of any conditions that could affect the installation. The designer’s specification should require the mirror be mounted on proper structural support or blocking. The specification would also require hardware sufficient to support the weight.
In California and other parts of the country prone to earthquakes, the designer could be subject to even more stringent requirements.