The old Navy blimp hanger (current airplane museum) in Tillamook Oregon bills itself as the largest wooden building in the world:
Length: 1,072 feet
Height: 192 feet
(over 15 stories)
Width: 296 feet
Area: Over 7 acres
(enough to play six football games)
Doors: 120 ft. high,
6 sections each weighing 30 tons.
220 ft. wide opening. The sections roll on railroad tracks
Catwalks: 2 catwalks, each 137 ft. above the hangar deck
http://www.tillamookair.com/
I don't know if they're telling the truth or not but it is indeed a very big and very cool building.