A Wood Deck Dictionary

“A deck is essentially an outdoor floor supported by a frame, posts, and footings secured in the ground; assembled in stages; and built from the ground up. The following terms define all of the important components of a typical deck.”
Source: woodmagazine.com

If you’re planning to build, update, or design a wood deck, understanding the key deck construction terms can make a big difference. Knowing the terminology lets you communicate to clearly avoid costly mistakes and make smarter choices along the way. This guide includes an easy-to-follow deck diagram that shows all the essential parts that make up a deck, notes on lumber sizing and a decking dictionary explaining each component and its role in the deck structure.

Pressure-treated Southern Yellow Pine is the ideal wood for the job and can be used for every component listed below. Its strength, versatility, and natural beauty make it a top choice for builders and DIYers alike, whether you’re constructing joists, beams, posts, or railings. Unlike composite materials, which can be costly and less adaptable, Southern Yellow Pine delivers reliable performance and a classic wood look that enhances any outdoor space. Best of all, it’s the most cost-effective option on the market, giving you lasting quality without breaking the budget.

Understanding lumber sizes is key to speaking the language of deck building. Terms like 2×4 or 4×6 refer to nominal lumber dimensions, read as “two by four” or “four by six”, and are used throughout construction plans and material lists. These numbers refer to the lumber’s size before it’s planed smooth, so the actual dimensions are slightly smaller.

To help you get started, we listed and explained the most common deck building terms below. Whether you’re working with a contractor or taking on a DIY project, knowing the lingo for wood decking components will give you the confidence to plan and build a strong, safe, and beautiful outdoor space.

Decking Dictionary of Common Construction Terms*

Baluster
A baluster is a vertical post that supports the handrail of a staircase or guardrail of a deck, balcony, or porch. They are spaced evenly to provide safety and prevent people from falling through openings. A group of balusters is often referred to as a balustrade.

Beams or Girders
Beams or girders are large horizontal framing members, typically made from 4×6, 6×8, or doubled/tripled 2×10 lumber, that span between posts and support the joists above. They’re essential for distributing the deck’s weight and providing a stable structure.

Bridging
Bridging refers to short boards installed between joists to add lateral support and prevent twisting or warping. This reinforcement improves the overall strength and stability of the deck frame.

Decking
Decking is the surface layer of a deck, the boards you walk on. Typically made from 2×6 or 5/4 lumber, decking boards are fastened to the joists and form the visible, usable platform of the deck.

Footings
Footings are below-ground concrete supports that hold up the deck’s vertical posts. They anchor the structure to the ground and help prevent shifting, especially important in regions where freezing and thawing soil can cause movement. In those areas, concrete is typically poured into a cylindrical hole or above-grade form. Be sure to check with your local building department for the required footing depth in your area.

Joists
Joists are horizontal framing boards, typically made from 2×6, 2×8 or 2×10 lumber, installed on top of beams or flush with the ledger. They support the decking and form the main structure of the deck floor. A header joist connects the ends of interior joists, while rim joists or end joists run along the outside edges, perpendicular to the ledger, framing the outer perimeter of the deck.

Joist Hangers
Joist hangers are metal brackets that secure joists to other framing members, like ledgers or rim joists, without the need to notch the lumber. They ensure a strong connection and proper load transfer.

Ledger
A ledger is a horizontal board (usually 2×8 or 2×10 lumber) that is fastened directly to the house. It supports one side of the deck and acts as an anchor point for the joists.

Piers
Piers are precast concrete bases, often pyramid-shaped, that rest on footings or the ground. In areas without frost concerns, they can sit directly on the soil to support the vertical posts.

Post Anchors
Post anchors are metal connectors that attach deck posts to footings or piers. They lift the base of the post slightly above the surface, helping prevent moisture damage and rot.

Posts
Posts are vertical support members, typically made from 4×4 or 6×6 timbers, that connect the deck to the ground. They transfer the weight of the deck to the footings or piers and can also serve as railing supports.

Rails
Rails are the horizontal components of a deck railing system. They run between posts and serve as both safety barriers and handholds, especially on stairs or elevated decks.

Railing
A railing is the complete system that surrounds a deck for safety and design. It typically includes posts, top and bottom rails, cap rails, and balusters (or spindles). Balusters are spaced to prevent falls, no more than 4 inches apart for child safety.

Risers
Risers are the vertical boards between stair treads. While optional on outdoor steps, they give a finished look and help prevent debris buildup between steps.

Spindle
A spindle is a vertical, slender, and often decorative support element used in railings for stairs, decks, or balconies.

Stringers
Stringers are diagonal framing boards, often cut from 2×12 lumber, that support stair treads. They are typically spaced 12 to 16 inches apart and form the sides of the stair system. Check your local building code for approved spacing.

Treads
Treads are the horizontal boards you step on when using a staircase. They attach to the stringers and form the walking surface of the stairs.

* Portions of the above glossary were adapted and expanded from the decking dictionary originally published by Wood Magazine at woodmagazine.com.

Before you start building, here is a friendly reminder.

All structural components, including posts, footings, beams, and connectors, must meet local building codes and requirements. Always consult your local building authority or a licensed professional before beginning construction to ensure your deck is safe and compliant.