Deck boards and screws for a rectangular deck.
AdvertisementA 16x12 ft deck with 5.5 in boards needs 29 boards of 16 ft, including 10% extra.
Boards run along the deck's length. We divide the deck's width by one board plus its gap to get the number of rows, multiply by the length, add 10% for cuts, and divide by the board length. Screws are two per board at every joist.
About 1/8 in for kiln-dried or composite boards. Wet pressure-treated boards can go tight together because they shrink as they dry.
16 in on center for most wood and composite decking; 12 in for diagonal layouts or thinner composite boards. Check the manufacturer's span rating.
About 29 boards of 12 ft, using 5.5 in boards with a 1/8 in gap: 26 rows plus 10% extra for cuts.
Across the joists, at a right angle. Boards laid at 45 degrees look good but need joists closer together, usually 12 in apart.