A deck collapsed last week at a frat house in Blacksburg, Virginia, home of Virginia Tech. Virginia Tech is well known to deck builders as the test facility that showed the weaknesses in common railing and ledger attachment details. Although 30 students were on the deck at the time of the collapse, no one was reported injured.
A local building official blamed the collapse on excess occupancy, but I find that hard to believe. According to Wikipedia, the average male college student weighs in at 170 lbs. Thirty of them weigh 5100 lbs. Assuming a 40 psf design live load, any deck of 128 square feet or more should be able to handle that no problem. On a 128 square foot deck - which would measure a little larger than 10 x 12 - 30 deck users would only get 4.26 square feet apiece - A little more than 2 feet x 2 feet. That's Monday morning Manhattan subway close, not frat party close. I'm thinking there was something wrong with the deck.
In looking at the video in the link below, it appears that the ledger is still attached to the house. What I don't see anywhere are joist hangers. Makes you wonder, doesn't it?
http://www2.wsls.com/news/2012/oct/26/6/blacksburg-deck-collapses-students-it-ar-2313957/
