Dry rot fruiting body

What is dry rot and how to get rid of it?

23 October 2018

Put simply dry rot is a fungus that eats wood. Otherwise known as True Dry Rot Fungus (Serpula Lacrymans) it can truly have a devastating effect on a property if not caught and treated in its early stages. Dry rot spores are considered as omnipresent and no environment is considered to be totally free from them. The spores will germinate and grow on timber that has a moisture content of between 20% and 30%. The ideal breeding grounds for an fungal attack are timber combined with dampness and a lack of ventilation. The fine fungal thread (hypha) digests the cellulose and hemicellulose fraction of the woodturning the wood brown and ultimately reducing the timber to a dry and crumbly state. Dry rot does not attack the structural lignin of the wood.

Dry rot can take hold in all types of property. It shows no preference towards historic or modern as long as the perfect environment for growth exists. It can grow within the cracks and cavities of the walls feeding off debris and wood hidden behind the plaster.

The hypha remain as a brittle matrix which cracks into cubes and differential stresses. Cuboidal cracking which is also characteristic of many wet rots and does not automatically indicate the presence of dry rot. Fungal hyphae may clump together into a variety of structures known as mycelia which takes various forms depending on the surrounding conditions. They may fill a humus cavity as a cotton wool-like mass or grow across the surface of the timber as a grey/white skin.

Mycelium growth

Active dry rot (Serpula lacrymans) has a fresh white or greyish appearance. Some hyphae grouped together to form conducting strands. Their main function is the conduction of nutrients through inert non-nutrient material i.e. brickwork, to permit eventual colonisation of the timbers. The relatively impervious outer layer, together with an unusually alkaline tolerance, allows them to survive in the mortar layers of the masonry and walls in an infested area may be full of dry rot strands.

Hyphae tracking through masonry

The dry rot fungus may tolerate relatively lower moisture content and, through this and other facets of its biology, it is potentially capable of considerable destruction within a building.

How to get rid of dry rot

At Timberwise we have over 50 years experience in successfully identifying and treating dry rot in buildings.

To get rid of dry rot our timber surveyors and trained technicians will do the following:

  • By carrying out an extensive survey our surveyor will identify the type, nature and extent of the outbreak of dry rot.
  • Find the root cause of the outbreak by finding and removing the source of moisture which is fundamental for dry rot to grow.
  • The surveyor will provide a report of the findings along with a proposal for getting rid of the dry rot along with a full specification of the work required.
  • When the work on removing the rot commences our technicians will remove any wood or plaster works that are contaminated with dry rot and replace with treated timber and fresh plaster.
  • All works come with the Timberwise 20 year guarantee for peace of mind that you are rid of dry rot for good.

A recent example of an outbreak of true dry rot was found by our experts in a church in Liverpool. The outbreak was discovered in the rafters and a load bearing truss timber within the timber structure at ceiling level. On this occasion our dry rot specialist recommended a mass irrigation sterilisation treatment to the walls in excess of 150mm thick including a surface application to the exposed masonry in the vicinity. In areas where there was severe fungal decay sections of of the timbers were removed and replaced with closely matched timbers that were pre-treated with a fungicidal paste and damp proof membrane.

Prep for irrigation for Dry Rot

Do you need help with dry rot?

Depending on the severity of the dry rot outbreak there are many ways in which true dry rot can be treated. If you suspect that you may have a potential dry rot outbreak don’t panic! Simply speak to one of our dry rot specialists about the best way to treat the issue and prevent the fungal decay from returning. Contact an expert on 0800 288 8660 or complete our on-line survey request form to arrange a surveyor to visit your property to assist you further.

Originally published 28th October 2011, updated 23rd July 2019.