What is dry rot?
Dry rot, also called brown rot, is the common name for the decay of wood caused by the presence of a fungus Serpula lacrymans, the spores are common and germinate in wood with a moisture content of around 30 per cent, within an active temperature range between 18 and 32 degrees Celsius. Dry rot can proliferate in enclosed damp locations, under floor boards, around skirting boards and in ceiling joists.
When the fungal growth reaches an advanced stage it sends out strands (mycelium) that can travel through masonry to attack other wood sources. The fungus cannot attack or damage the masonry but it is able to absorb moisture from it and use it as a bridge to reach unaffected timber. Early detection is fundamental to preserving your premises, as this extremely damaging fungus is capable of destroying the structural integrity of any wood in a building if left untreated.
How to Identify Dry Rot:
Look for timber that is sunken or shrunken.
Examine the underside of floor boards, joists and roof timbers for traces of the fungus. In early stages, dry rot resembles white cotton sheeting, and when exposed to light may have a silkier appearance. Advanced dry rot will produce a mushroom odour and can produce an orange and brown spreading ring like growth on the timber exterior surfaces.
Check wood with damp and musty smell, look for a white growth on the wood, this is important if water damage is suspected. Examine any dust around the rotted area, dry rot dust has a red hue.
Look carefully at any area with wide, soft and fleshy wide spores, these may have an orange and green surface. Search for thick grey strands, these can be up to three millimeters in diameter, growing inside the cracked section of timber. Strands can be found alone without other symptoms of dry rot. The effect of this fungal attack can make the wood brittle and crack easily and can grow over other damp wood, possibly leading to dry rot.
Examine neighbouring timbers for extended spore activity. Dry wood that has been attacked internally by dry rot may have dark stains or pale stains. The affected wood may appear very dry or even cracked and fully damaged timber will easily break apart.
To check for dry rot use a sharp implement, like a small screwdriver to probe the middle of the affected area. If it goes through the wood easily, dry rot may be present. If the wood seems solid and dry, you may not have any major problems with the timber. However, you should look for cracks and rips in the wood that are susceptible to water damage.
If you suspect dry rot or are you are unsure if dry rot is present, it is advisable to call in some expert help.