"Flaws in construction" rather than overloading caused a chain reaction that led to the collapse of a multi-level deck, injuring 32 Trinity College students last month. That was the conclusion of a report issued by Cirrus Structural Engineering following their investigation of the accident at the 90-year-old home, which was purchased by Trinity College in 2011.
According to the report, the home's second- and third-floor decks were remodeled sometime between 1990 and 2003. Instead of being supported by a new ledger bolted directly to the framing, the new second-floor deck was supported by a ledger that was simply nailed to the original porch ledger, which in turn had been nailed to the sheathing when the home was built in 1929. Not only was this ledger assembly structurally inadequate, it also wasn't flashed, leading to fastener corrosion and a further reduction in load-bearing capacity. As the nailed connection failed, movement of the second-floor porch was transferred to the upper deck, which collapsed first. Witnesses say there were four people standing on the third-floor deck and 7 to 10 people standing on the second-floor deck at the time of the collapse.