Decking boards for a 3m x 3m deck: 20 boards

A 3m x 3m deck covers 9 m². With the UK standard — 125mm-wide deck boards in 3.6m lengths — you need:

Material	Quantity
Deck boards (125mm x 3.6m)	20 boards
Decking screws (approx.)	270
Joists at 400mm centres (4x2 C16)	9 runs x 3m

Add 5-10% extra boards for cuts, wastage and future repairs. For a shaped or multi-level deck, the numbers change — the planner computes exact counts from your drawn shape, including pedestals and a full cut list.

Related sizes

• 4m x 3m
• 5m x 3m
• 4m x 4m
• 5m x 4m
• 6m x 4m
• 5m x 5m
• 6m x 6m
• 3.6m x 3.6m
• 8m x 4m
• 2.4m x 2.4m
• 3m x 2m
• 4m x 2m
• 5m x 2m
• 6m x 3m
• 7m x 4m
• 8m x 5m
• Joist spacing rules for UK decks
• Board spacing: the gaps that stop rot
• How many screws per m²
• Composite vs timber: real costs
• How many sleepers for a raised bed

Buy the materials

Composite decking boards Low maintenance, 25yr+ life Pressure-treated timber deck boards Classic, cheaper upfront Stainless decking screws Countersunk, anti-corrosion

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