Wood Decay Fungi & Wood rot, its a Big Problem…

 Wood Decay – It’s a Big Problem…

Wood decay fungi – aka wood rot

Wood rot or wood decay is the most common defect found in Sydney properties and is mostly underestimated by homebuyers, property owners and property professionals. Wood decay causes significantly more damage (in dollar value) than termites and can have far reaching structural consequences, particularly in external timber structures, such as steps, handrails and decks/verandahs. It is important for the homebuyer to have a clear picture of any wood decay in the building or grounds and be aware of any conditions that are conducive to wood decay. Wood decay, or wood rot is caused by fungi – organisms that live on other organic matter such as wood. The very fine spores of these fungi are abundant in the air and under favorable conditions; the right temperature and dampness levels, and in the presence of oxygen the fungi will attack wood. There are several broad groups of wood decay fungi.

Brown Rot

  • Attacks the cellulose (the bulk material of wood) and leaves chemically degraded lignin (the glue that binds the cells together) – the brown colour
  • Can delete up to 65% of the weight of the timber.
  • Tends to spread from cell to cell fast.
  • Affected wood appears in better condition than it is.
  • Can be on the surface of the timber or inside the wood.
  • In the advanced stage, timber often forms into cube like appearance.

White Rot

  • Attacks lignin and cellulose and leaves timber white in colour.
  • Can delete up to 100% of Timber weight
  • Cells decompose from the centre outwards and completely destroys the cell before moving onto the next cell.
  • Can be on the surface or inside the wood.
  • In the advanced stage, the timber has a stringy appearance.

Soft Rot

  • Generally wood is a darkish colour.
  • Usually found on the expanded surface of the wood and extending inwards.
  • In eth advanced stage the damaged wood is very soft and cheesy when wet and is very brittle with shrinkage checks when dry.


Moulds are a type of fungi. Their activity is confined mainly to the surface of the wood. They feed on the contents of the cells and because they do not breakdown the cell walls, they have little of no effect on the strength of the timber. When the timber dries the mould cannot continue. Moulds are unsightly but not a danger to the building. Moulds are indicators of high moisture content in the air. This is often an indicator of more systematic damp related problems such as faulty roof plumbing or poor site drainage.