I set out to replace the boards on our backyard deck this summer, and initially tried removing the old boards with a three-foot crowbar. The main problem was getting it between the deck board and the joist, so I could start prying. This required a hammer to drive it under the board. Then with a lot of effort, time and hammering I eventually removed one board. Clearly not the way to do the entire deck.
After some searching I discovered the Duckbill Deck Wrecker. This thing is a monster. It sits on the joist and has two legs that straddle the joist and slip under the board you’re removing. With almost 4 1/2 feet of leverage it’s easy to pry up the board, progressing along its length every one or two joists. You stand on the old section of deck and push the handle of the Duckbill up, thus prying up the old board in front of you. As far as other tools go, Mayhew’s Cats Paw functions with a similar design, though without the rotating head. The Cats Paw has a little less leverage and costs a little more.
The first, outermost, board(s) must be removed some other way to expose enough joist so that the Duckbill can fit under a board. As you make your way closer to the house — putting down new boards as you take old ones up — eventually there isn’t room to stand behind the Duckbill. At this point you remove the Duckbill head (it’s pinned to the shaft and can be rotated 180°), turn it around and now you are standing on the new decking and pulling the handle of the Duckbill to remove the last few old boards.
I’m sure I will find some other uses for this thing, but even if it’s only good for decks, it was well worth the money.