Enter your Deck Length, Width, Board Size, Joist Spacing, Decking Angle, Waste Factor, and Perimeter Length into the Composite Decking Calculator to find your Total Deck Area, how many Decking Boards you need, Linear Feet Required, and total Fasteners Needed.
Total Deck Area
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Decking Boards Needed
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Boards with Waste Factor
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Linear Feet Required
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Fasteners/Screws Needed
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Trim Boards for Perimeter
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The number of boards depends on your deck size, board width, and layout angle. For a 12x16 ft deck with 5.5" wide boards laid perpendicular, you'll need approximately 35-40 boards including waste factor.
The most popular sizes are 5/4" x 6" and 2" x 6" for width, with lengths typically 12', 16', or 20'. The 5/4" x 6" size offers the best balance of coverage and structural integrity for most residential decks.
Include 5-15% waste factor depending on your deck's complexity. Simple rectangular decks need 5-10%, while decks with angles, curves, or complex cuts should use 10-15% to account for material waste during installation.
You'll need hidden fasteners or deck screws (about 350-400 per 100 sq ft), trim boards for finishing edges, and potentially additional structural lumber for joists if building new framing.
Measure the length and width at the longest points, including any overhangs. For irregular shapes, break the deck into rectangles and calculate each section separately, then add the totals together.
90° (perpendicular) installation is easier, uses less material, and provides standard coverage. 45° (diagonal) creates a more premium look but requires 15-20% more material and more complex cuts at the edges.
Plan for 3.5-4 fasteners per square foot when using hidden fastening systems, or about 350-400 fasteners per 100 square feet of decking area.
16" on center is the most common spacing for composite boards. Some thinner boards may require 12" spacing, while thicker boards can span up to 24". Check your specific product requirements before installation.