Garden Decking Calculator

Calculate the materials for a practical garden decking build using standard joist and post spacing.

Decking materials for a 3.6m by 1.8m deck

For a deck measuring 3.6 metres by 1.8 metres, this estimate recommends 15 boards (3.6m lengths) plus joists at 400mm centres, 150mm noggins, posts, screws, weed membrane and sub-base using the default UK assumptions shown below.

  • Deck area6.48 m²
  • Deck boards15 boards (3.6m lengths)
  • Joists6 joists / 21.60 lm
  • Noggins5 pieces (150mm timber)
  • Posts6 posts
  • Structural bolts12 bolts
  • Decking screws172 screws
  • Weed membrane7.13 m²
  • Sub-base0.65 m³ / 1.17 tonnes

Results - Garden Decking Calculator

  • Deck area6.48 m²
  • Deck boards15 boards (3.6m lengths)
  • Joists6 joists / 21.60 lm
  • Noggins5 pieces (150mm timber)
  • Posts6 posts
  • Structural bolts12 bolts
  • Decking screws172 screws
  • Weed membrane7.13 m²
  • Sub-base0.65 m³ / 1.17 tonnes

Garden decking notes

This is the garden-decking variant of the main decking estimator, useful for landscaping-led searches while keeping the same practical build assumptions.

Disclaimer

Material quantities shown are estimates for guidance only. Although typical UK wastage and compaction allowances have been included, actual requirements may vary depending on site conditions, installation methods, and material differences. Please confirm quantities with your installer or supplier before ordering. We accept no liability for inaccuracies, financial loss, or delays arising from the use of these estimates.