Construction & Trade
Decking Calculator
Calculate decking boards, joists, fixings, and cost for a new deck based on dimensions and board size.
How this calculator works
Calculates the number of boards (deck width / (board width + gap)), each at the deck length. Calculates joists (deck length / joist spacing + 1) each at the deck width. Adds waste factor, then estimates fixings (approximately 20-25 screws per m²). Totals all material costs.
Common: 90mm (merbau), 138mm (composite). Include gap.
450mm for hardwood, 400mm for composite, 600mm for softwood
Merbau ~$10-15/lm. Composite ~$15-25/lm. Treated pine ~$5-8/lm.
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FAQ
Frequently asked questions
How much does a deck cost in Australia?
DIY materials for a 15m² merbau deck cost approximately $2,500-$4,000. Professionally built: $350-$600/m² for hardwood, $300-$500/m² for composite, $200-$350/m² for treated pine. These prices include subframe, boards, and basic stairs.
Do I need a permit to build a deck?
In most Australian states, decks under 1m high and under a certain area (10m² in some states, 20m² in others) are exempt from building approval. Anything higher or larger usually needs a building permit. Always check with your local council.
What is the best decking timber in Australia?
Merbau is the most popular for its durability, colour, and value. Spotted gum and ironbark are premium Australian hardwoods. Treated pine is budget-friendly. Composite decking (like Modwood) is low-maintenance but costs more upfront.
How long does merbau decking last?
Properly maintained merbau decking lasts 25-40 years. Oil it every 12-18 months with a quality decking oil. It will bleed tannins (red staining) for the first few months — this is normal and washes away over time.
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