Deck Building Guide

Gap Spacing

A 5mm gap between boards allows drainage and expansion. Green or wet timber needs a 3–5mm gap at installation — it will shrink as it dries. Pre-dried or composite decking can use 3mm. Never butt boards tight — they will cup and heave.

Board Direction

Running boards along the length of a deck (parallel to the house) is most common and has less waste. A diagonal pattern uses 15–20% more material but looks striking. Always plan the pattern before cutting.

Composite vs Timber

Composite decking costs more upfront but needs no staining, sealing, or annual treatment. Over 10 years, total cost of ownership can be lower than pressure-treated timber. Always check manufacturer's installation gap requirements — they vary.

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