Millions of decks are built each year but over half of existing decks may be unsafe, as deck failures and collapses increase in summer and can occur when occupied or under snow loads. While deck failures do not correlate with whether a permit was obtained or who built the deck, they do correlate with age. Most collapses happen when the house and deck ledger board separate, though rail failures cause more injuries than full collapses. Proper deck inspections rely on the inspector's professional judgment and should start by inspecting the areas below the deck.