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By: Frank Woeste

Deck collapses caused by failure of a nailed deck-ledger-connection to the structure or house have been followed since 2002, when researchers at Virginia Tech began to investigate and test critical structural elements of a residential/multi-family deck. After several years of tracking deck collapses, it became apparent that the primary cause of deck collapses was the connection of the deck ledger to the house made with nails only. In fact, I believe 90% of all deck collapses result from the failure of the deck ledger-to house connection, and of the 90% most are caused by nailed-only ledgers.

The focus of this article is existing decks with a “nailed-only” ledger connection. As will be demonstrated, a homeowner, home inspector, property manager, or other professional can quickly determine if the deck is dangerous—nails only in a deck ledger constitutes a “dangerous deck.”

Background For decades, the residential codes have specified an occupant deck load of 40 pounds-per-square foot (psf), which translates into about one average-size person locating a space of 2-ft. by 2-ft. In addition, every edition of the International Residential Code (IRC) since 2000 has required that decks be positively anchored to the structure to resist both vertical and lateral loads. Assuming a deck that is 14-ft by 28-ft, the code design load would anticipate the deck could be safely occupied by 98 people. However, until 2007, the IRC did not prescriptively specify how contractors should fasten or connect the deck ledger to the house.

 

 

 

 

 

 

 

 

Frank Woeste, P.E., is Professor
Emeritus, Virginia Tech University
and a wood construction consultant.
He can be contacted by e-mail: fwoeste@vt.edu

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