Garden Decking Calculator
Calculate the materials for a practical garden decking build using standard joist and post spacing.
Decking materials for a 4.2m by 2.4m deck
For a deck measuring 4.2 metres by 2.4 metres, this estimate recommends 38 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 area10.08 m²
- Deck boards38 boards (3.6m lengths)
- Joists7 joists / 29.40 lm
- Noggins12 pieces (150mm timber)
- Posts8 posts
- Structural bolts16 bolts
- Decking screws262 screws
- Weed membrane11.09 m²
- Sub-base1.01 m³ / 1.81 tonnes
Results - Garden Decking Calculator
- Deck area10.08 m²
- Deck boards38 boards (3.6m lengths)
- Joists7 joists / 29.40 lm
- Noggins12 pieces (150mm timber)
- Posts8 posts
- Structural bolts16 bolts
- Decking screws262 screws
- Weed membrane11.09 m²
- Sub-base1.01 m³ / 1.81 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.
Popular sizes
These decking presets cover the board-and-joist sizes people actually price up for garden platforms, seating areas and raised decks.
Garden decking searches usually revolve around standard entertainment areas, hot tub surrounds and raised seating platforms. Pages such as 2.4m × 1.8m, 3m × 1.8m, 2.4m × 2.4m, 3.6m × 1.8m create direct landing pages for board counts, joists, posts, screws and ground preparation materials.