Common Deck Terms & Definitions

Composite Decking: Decking made of composite materials, or composite decking, is created by the infusion of plastic wood and fibers. The combination of these and other chemicals forms a decking profile which requires less maintenance and generally has a shorter life span than natural wood.

Expansion and Contraction: When put in a warm setting, or when heated, deck boards will expand. When in a cool environment, deck boards will contract. When spacing deck boards, this disparity needs to be taken into account.

Deck Fasteners: Deck term for screws, nails, bolts, and other devices that connect decking materials together.

Grade: The grade of a piece of a lumber designation which indicates the amount of general flaws and/or knots found in a piece of wood decking.

Inset: A specific area of the deck boards that has been cut out to make room for decorative items and certain and landscape elements like trees, or bushes.

Janka Hardness: A test measuring the hardness of wood. This test measures the force required to push a ball bearing made of solid steel into the wood to a depth of half the ball’s diameter. The more force it takes the push the steel ball into the wood, the higher the janka rating.

Joist: This system of sub-deck structural elements is to be built and completed underneath the deck boards. A joist is meant to adequately support your deck, these horizontal frame members are usually built with 2 x 6 or 2 x 8 lumber.

Linear Feet: The total length of lumber that you need for your deck. For example, eight 12-foot-long 2x4s would result in 144 lineal feet.

Net Dimensions: After a piece of decking with nominal dimensions of 2"x4" has been finished by either sanding or planing, the decking's actual, or net dimensions will be determined (1 1/2" x 3 1/2").

Nominal Dimensions: This is the name given to a pre-finished piece of decking and lumber, in general. For example, 2x4 is the label for a pre-finished / rough-cut piece of decking that has a size of roughly 2"x4".

Post Cap: This piece of decking material is meant to be to cover and protect a deck post's wood grain. There can be many variations of post caps and many are decorative.

Decking PartsJanka hardness test