There are several types of timber decay or wood rotting fungi. These are divided into categories such as "Brown or White" rots, as well as "Dry or Wet" rots. There is, however, only one Dry Rot (Serpula lacrymans). This rot is by far the most destructive fungus found in buildings. It is often referred to as "the cancer of wood". This disease has the ability to hide in behind walls undetected causing horrific damage for years on end before it becomes obvious to the untrained eye.
Once the fruiting body reaches maturity (Fig 2a) it will produce millions of spores by the hour! Airborne spores are ever present, but the conditions must be just right for the germination process to begin. The spores appear as a rusty brown dust to the naked eye (Fig 2b). Buildings known to have had an outbreak of dry rot are more prone to re-infestation as these spores can lie dormant but be ready for action and completely undetected for years. Therefore, in a case like this, the property owner should be vigilant with a regular maintenance routine and frequent inspections.
If the conditions are right for the spores to become active, they start by growing into what is referred to as "Hyphea" or a fine cotton wool like substance. If there is plenty of food around such as organic material like wood, the Hyphea will accelerate its growth and begin clumping together and form what is known as Mycelium which looks like thick strands of wool. (Fig 2c) It is this Mycelium that actually attacks the wood where it basically taps into the cells of the wood and sucks all the goodness out leaving the wood cracked into cubes and split as seen in (Fig 2c) You will note in this photograph that the inner section of the piece of timber is devastated by the dry rot whilst the outer surface is left looking sound!
Treatment - Well, this again is a topic for great debate. What it basically boils down to is how much responsibility any contractor or individual is prepared to take and how much the customer is prepared to pay for it! This industry is renown for its "gut it out and pump it full of poison" attitude. Not only is this destructive, costly, stressful and often unnecessary, but it contaminates our precious environment and doesn’t always work. (Fig 2d) shows a new joist end, which is a pre-treated piece of timber wrapped in a dpc felt and built into a wall that had been saturated with a fungicidal solution. This is a result after only 4 years! There are “Alternative” measures that can be applied!