Deck Floor Spaces Between Planks

Nail Spacing

• Deck boards that are 2 inches thick should have about a 1/8 inch space between them, according to the Ace Hardware Corporation. The company indicates that builders usually set a 16d nail between the planks as they assemble deck floors to achieve the correct spacing. The "d" in 16d nails stands for penny, and builders and hardware suppliers often refer to them as 16 penny nails. The 16d nail is 3 1/2 inches long, so it will be easy to see between deck planks as you're spacing them.

Wet vs. Dry Planks

• The "Hometime" home improvement website recommends using 16d nails to space deck planks if the planks are mostly dry. The site indicates that you can assemble a deck floor without spacing the planks when the planks are wet. Wood expands when it absorbs moisture. Therefore, adequate spacing would likely occur naturally as wet deck boards dry and shrink back to their original width.

Pressure-Treated Lumber

• You could use lath strips to create even spacing between deck boards instead of 16d nails, according to "Ask the Builder" columnist and builder Tim Carter. Lath strips are thin pieces of wood that are sometimes nailed to wall studs to support the application of plaster. However, Carter recommends not adding spaces between planks if you're using pressure-treated lumber to build your deck. He reports that lumber that’s 3 1/2 inches wide can shrink as much as 3/16 inch as a deck is exposed to the elements. The shrinkage could create spaces between planks that are too wide if you also spaced them upon installation.

Considerations

• The type of material used to build your deck ultimately determines how much space should be between the planks. For example, Carter indicates that it's important to ask your lumber supplier if cedar decking is kiln-dried or air-dried. He warns do-it-yourselfers not to leave space between air-dried cedar planks because they will shrink significantly. Redwood is more stable and can be spaced upon installation using 16d nails or lath strips, according to Carter.