Frequently asked questions
How many deck boards do I need?
Rows = deck width ÷ (board width + gap), then divide the deck length by the board length for boards per row. A standard 1/4 in gap (5–6 mm) is included; the calculator adds 10% for cuts.
What joist spacing for decking?
16 in on center is standard for 5/4 wood decking perpendicular to joists. Composite boards and diagonal layouts usually require 12 in — check the board manufacturer's span chart.
How many screws per deck board?
Two screws at every board-joist intersection. A 12 ft board over joists at 16 in gets about 20 screws; the calculator counts intersections exactly.
About this calculation
This calculator uses the dimensions, waste allowance and material sizes entered above. MaterialCalc is developed by Igors Beļavskis, a construction contractor in Latvia. Results are planning estimates; confirm product coverage, local rules and site conditions before ordering.
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