The balcony in California that collapsed in 2015 killing six students - five of whom were Irish - was built using unstable materials, a new report suggests.
The technical report from the California Contractors State Licensing Board (CSLB) concluded that the balcony in Berkeley ought to have been able to take the load of 13 students who were on it on the night of June 16th, 2015.
The tragedy at the Library Gardens apartment complex ended in the deaths of Dublin students Olivia Burke, Eoghan Culligan, Lorcán Miller, Nick Schuster and Eimear Walsh, all aged 21, and Ms Burke's cousin Ashley Donohoe (22), who was from Rohnert Park, California.
A report by consultant architect Robert Perry identified the cause of Unit 405's balcony collapse as dry rot damage, which occurred along the top of the cantilever balcony deck joists.
His analysis identified water damage between the joists and the flooring of the balcony, which was made of oriented strand board (OSB).
Mr Perry found that when the balcony was constructed, a protective membrane was not put on the OSB to protect it from water damage.
He explained that OSB is a more water absorbent material than plywood, which was supposed to have been used in the construction of the balcony.
This was especially relevant as Berkeley receives an average of 645mm of rain every year most of it during the wintertime.
Mr Perry noted that during the construction of the apartment complex between October 2005 and August 2006, almost 1,000mm of rain fell, but there was “no mention of framing protection from inclement weather” in construction logs.
Last month the CSLB revoked the contractor’s licence of Segue Construction, which built the apartment complex.
The regulator said the company’s subcontractors “wilfully departed from or disregarded the specifications” of the balconies at the Library Garden’s complex when constructing them, using incorrect materials and failing to install necessary support joists.
It found that the “design and load analysis of the balcony established that if the balcony has been built as designed, the imposed load of the 13 students was well within the design limits of the balcony structure”, and would not have collapsed.
The California contractor licensing board alleged the company “wilfully departed from accepted trade standards for good and workmanlike construction in the building of the Berkeley apartment complex”.
Segue Construction entered into the contract to build the 176-unit Library Gardens apartment complex on January 20th, 2005, completing the job two years later.
The construction firm had hired various subcontractors to work on the project. Subcontractors hired to provide carpentry and waterproofing work failed to build the balconies to the required standard and specification, it was found.