Timber Movement

Wood is hygroscopic, which means its moisture content (MC) will fluctuate based on the relative humidity (RH)of the surrounding air. As humidity increases, the MC increases, and the wood expands, and as the humidity decreases, MC decreases, and the wood shrinks - this is an unchangeable fact however movement can be accurately predicted and allowed for! Mortlock Timber offers a range of low movement species and can offer advice on allowing for timber movement.

The cell structure of wood has been likened to a number of drinking straws that are glued together. With regard to this, water in wood resides both within the “straws” (called free water) and in the walls of the “straws” (bound water).  If timber is under high exposure the straws fill with water which causes the timber to expand rapidly - hence the reason why it’s important to seal the timber and the end grain correctly and cap off wall cavities during construction to prevent pre-longed water exposure to the back of cladding boards.

Pacific Teak is a naturally stable hardwood which offers very low shrinkage. This means when exposed to the harsh Australian climate it stays dimensionally stable - perfect for exterior timber applications such as cladding and decking. Burnt Ash is a thermally modified species which means it under goes a thermal modification process that seals the cell structure or "drinking straws" - this greatly reduces movement and increases durability.

Pacific Teak Timber Battens & External Wall Cladding

Pacific Teak Timber Battens & External Wall Cladding

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References: Wood Solutions

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