Deck Building Material Estimator
Use this calculator to estimate the primary materials needed for your deck project, including deck boards, joists, support posts, and concrete for footings. This tool helps you plan your material purchases more accurately.
Understanding Your Deck Building Materials
Building a deck is a rewarding project that enhances your outdoor living space. Accurate material estimation is crucial for staying on budget and avoiding delays. This calculator helps you get a head start on planning by estimating key structural and surface components.
Deck Boards
Deck boards form the walking surface of your deck. They are typically made from treated lumber, composite materials, or exotic hardwoods. When calculating, it's important to use the actual width of the board, not the nominal size (e.g., a "6-inch" board is often 5.5 inches wide). The calculator determines the total linear feet required, assuming boards run along the length of the deck, and then provides an approximate number of standard-length boards (like 12-footers) you might need.
Example: For a 16-foot long, 12-foot wide deck using 5.5-inch wide boards, you'd need approximately 26 boards across the 12-foot width. Each board would be 16 feet long, totaling 416 linear feet of decking.
Joists
Joists are the horizontal framing members that support the deck boards and transfer the load to the beams and posts. They are typically spaced 12 or 16 inches on center, depending on local building codes and the type of decking material used. Closer spacing provides a stiffer deck. Our calculator assumes joists run perpendicular to the deck boards, spanning the width of the deck, and includes an extra joist for the rim joist at the end.
Example: For a 16-foot long deck with joists spaced 16 inches on center, you would need about 13 joists. If your deck is 12 feet wide, each joist would be 12 feet long, totaling 156 linear feet of joists.
Support Posts
Support posts are the vertical members that transfer the deck's weight to the footings. Their spacing is critical for structural integrity and is determined by the size of your beams and local building codes. Common spacing ranges from 6 to 10 feet on center. This calculator estimates the total number of posts needed by assuming a grid pattern across the entire deck area, providing a robust support structure.
Example: A 16-foot by 12-foot deck with posts spaced 8 feet on center would require 3 posts along the 16-foot side (at 0, 8, and 16 feet) and 2 posts along the 12-foot side (at 0 and 12 feet). This results in a total of 3 x 2 = 6 posts.
Concrete Footings
Footings are the concrete bases that support the posts, distributing the deck's weight over a larger area of soil to prevent settling. The diameter and depth of footings are determined by local frost line requirements and soil conditions. The calculator estimates the total cubic yards of concrete needed based on the number of posts and the specified footing dimensions.
Example: If you have 6 posts, and each footing is 10 inches in diameter and 24 inches deep, the calculator will sum the volume of these cylindrical footings and convert it to cubic yards, which is how concrete is typically ordered.
Remember, this calculator provides estimates. Always consult local building codes, a structural engineer, or a qualified contractor for precise plans and material lists tailored to your specific project and location.