Lowes Deck Calculator

Understanding Your Deck Material Needs

Building a deck is a rewarding home improvement project. To ensure you purchase the right amount of materials and avoid costly trips back to the store, a proper calculation is essential. This calculator helps estimate the number of decking boards, joists, and railing components you'll need for your project, based on common construction practices.

How the Calculator Works:

This calculator breaks down the material estimation into several key components:

• Decking Boards: The calculation determines the total linear feet of decking required. It accounts for the surface area of your deck (width x length) and the width of your chosen decking boards. A waste factor is included to account for cuts, mistakes, and unusable board sections.
• Joists: Joists are the structural beams that support the decking. They are typically spaced 16 inches on center (OC). This calculator estimates the number of joists needed by dividing the deck's width (or length, depending on orientation) by the joist spacing and adding one for the end. It also calculates the total linear feet of joist material.
• Ledger Board: If your deck attaches to your house, a ledger board is required. The calculator uses the provided length to estimate the material needed for this structural element.
• Railing: For decks above a certain height, railing is a safety requirement. The calculator uses the total linear feet of railing needed to estimate material requirements.

Key Factors and Assumptions:

• Decking Board Width: Standard nominal "6-inch" deck boards are actually about 5.5 inches wide. The calculator uses this actual width by default.
• Joist Spacing: 16 inches on center is a common standard for joist spacing in deck construction. Some applications might use 12 or 24 inches.
• Waste Factor: A 10% waste factor is a good starting point. You might increase this for complex shapes or if you're less experienced with cuts.
• Board Lengths: This calculator provides total linear feet or board counts. You'll need to factor in standard lumber lengths (e.g., 8ft, 10ft, 12ft) when purchasing to minimize waste.
• Overhangs: This calculation assumes minimal or no significant overhang beyond the joist and rim joist.
• Stairs/Stair Stringers: Stair construction is not directly included in this simplified calculator. You will need to estimate stringer materials separately.

Example Calculation:

Let's say you're building a deck that is 12 feet wide and 16 feet long, with joists spaced 16 inches on center. You plan to use standard 5.5-inch wide decking boards and want to include a 10% waste factor. Your deck attaches to the house along a 12-foot ledger board and requires 30 linear feet of railing.

• Decking Area: 12 ft * 16 ft = 192 sq ft
• Linear Feet of Decking: (192 sq ft * 12 inches/ft) / 5.5 inches/board = ~418 linear feet
• Total Decking Needed (with 10% waste): 418 * 1.10 = ~460 linear feet. (This would translate to roughly 37 boards if using 12ft lengths: 460 / 12 = 38.3, rounded up).
• Number of Joists: (16 ft * 12 inches/ft) / 16 inches spacing = 12 spaces. Add 1 for the end = 13 joists.
• Total Joist Material: 13 joists * 16 ft length = 208 linear feet.
• Ledger Board: 12 linear feet.
• Railing: 30 linear feet.

Always double-check your measurements and consult with building codes in your area before starting your project.