Dry Rot Control

Introduction to Dry Rot (Serpula lacrymans)

There are two types of wood rot – brown rots and white rots.

Brown rots feed on the cellulose and lignin content of the wood cell structure and white rots feed on the lignin content only. This results in different degrees of attacks to timbers.

Dry Rot (Serpula lacrymans) is a brown rot. The fundamental difference between Dry Rot and all the other wood rots is that it has the ability to seek out new timber to attack through inorganic ‘barriers’, such as brick walls, underneath concrete etc.

The fungus is also able to control the moisture levels in any new timber it finds. So if the moisture content in a new piece of timber is too low the fungus can transfer moisture from its source to allow the fungus to thrive. Correspondingly if a piece of timber is too wet (i.e. there is not enough free oxygen inside the cells of the timber) the fungus will extract moisture from the timber to allow it to ‘consume’ it.

We need 4 ‘ingredients’ for a wood rot to start in a building. These are: -

• Timber – which is the food source (rather obviously)
• Fungal spores
• Water
• Oxygen

Removing any one of these ingredients from the equation will prevents dry rot from occurring.
We can’t remove every piece of timber from our properties.
Spores unfortunately are almost everywhere and are virtually invisible to the naked eye.
Oxygen is also a difficult one to control!
This leaves one ingredient that we can effectively control – water.

Unfortunately a lot of the timber we place in buildings is in areas where it is susceptible to moisture ingress. Such as suspended ground floors, roofs and areas where we use water, such as bathrooms and kitchens.
A lot of timber that is susceptible to dry rot is covered up or embedded in walls, such as wooden lintels over doorways, door frames, floor joist ends built into walls etc.
Any timbers that come in prolonged contact with water will eventually rot.

An outbreak of dry rot will always starts in or around wet timbers, but can continue to grow with a restricted moisture supply, spreading extensively through masonry to attack any timbers it meets. Severe structural damage to timbers in buildings can result, and specialist treatments are always required.

Assessment of Dry Rot

The first stage of dealing with any outbreak of dry rot is to carry out a inspection of the affected area in the property.
Initially to make sure it is actually Dry Rot!

The most important task is to identify the source of moisture for the outbreak and stop / control it.
Then we need to determine the full extent of the outbreak. This in itself can be a very difficult task and can usually only be done after you start stripping out the affected areas.

Once we know the full extent we can recommend a course of action, including the following:-

• Steps to control the moisture or water ingress
• The full extent of repairs & reinstatement works necessary
• The extent and type of chemical treatments necessary.

Remove Dry Rot

Contact a PPS member now to eradicate your Dry Rot!