Decking Calculator
Estimate decking boards from deck dimensions, board width, gap, and allowance.
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About Decking Calculator
Decking Calculator estimates total timber decking boards, joist lengths, and cut waste allowances needed to build a garden deck.
How to use Decking Calculator
- Enter deck length and width in metres.
- Select board width and board expansion gap width in millimetres.
- Specify waste allowance percentage (typically 10%).
- Click Calculate to estimate total board length and board counts.
Examples
Deck: 4m x 3m, Board Width: 120mm, Gap: 5mm, 10% waste Result: 106 metres total board length required (approx 36 boards at 3m length).
FAQ
Why are expansion gaps necessary between decking boards?
Timber decking boards expand when wet; expansion gaps prevent boards from cupping or warping against neighboring boards.
What joist spacing is recommended for timber decking?
Standard domestic timber decking requires joist centers spaced no wider than 400mm apart.