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Wood Rot

Wood used in construction must be protected for excessive water if it is to remain free from decay and the organisms that can feed on wet wood. 

Where buildings have defects, are poorly maintained, are subject to inundation or affected by condensation, water can lead to wood rot. 

Where timbers become affected by rots, action should be taken quickly in order to limit damage, prevent spread and save valuable constitution elements before structural failure and collapse of timbers and the maisonry they may support fails and collapses.

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Wet rot - fungal growth - PCA

Common Forms of Fungal Decay in wood & timber

The wood destroying fungi most associated with wood rot in buildings are often divided in two: Wet Rots and Dry Rots. Though this is really a very misleading way of considering things, we will attempt to understand why this is the case. 

Dry rot

Dry rot (Serpula lacrymans) can occur in buildings where timbers built into walls and floors have become wet and have lain undisturbed. Dry rot can spread relatively quickly in the right conditions and can even grow over maisonry in order to colonse susceptible wood that may be close by. 

Wet rots

Wet rots do not have to be any wetter than dry rots to grow. The term is often used to try and describe any number of fungi that are seen in buildings that are not Serpula lacrymans. These could include common names such as cellar fungus and mine fungus are used to describe the characteristics and habitats for these frequently encountered rots. Although they can be as destructive as dry rot, their extent of decay is usually limited to the areas that are regularly wet or where they are built into masonry. Wet rots are typically not described as spreading, though they will colonise and destroy any wood that is sufficiently wet. . 

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Controlling wood rot & decay

The control and eradication of timber decaying fungi is always focused on elimination of free water. Without water the fungi can not grow, and if the fungi is unable to grow, the wood will dry out and become stable. 

It is however, important to recognise that the elimination of water from a structure is often difficult, complicated and slow. Timber/wood affected by rot & decay may well be compromised, leading to loss of strength, mass, integrity. This may result in localised or widespread structural failures. 

It is essential that where timber decay has occurred then a specialist is engaged to investigate the cause of the water ingress, the nature and extent of the decay organisms, explore and then draw together a plan for the permanent eradication of the rot as well as it’s causes. 

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Treatment and repair

The control and eradication of wood rot & decay must always start with an understanding of the cause. Until water ingress is arrested and the conditions that lead to the outbreak of rots is addressed, a long term remey that preserves the timber and the building integrity can not be assured. 

Repairs, replacements and reinforcing rotten & decayed timbers will be necessary to address the damaging effects of rots. Structural drying, re-engineerings and detail alterations may also help return the building to a moisture safe condition. The use of chemical fungicides can be effective in protecting vulnerable timber in the short term, but these should only be used as part of an overall strategy of control that has the elimination of water as its principal means of long term eradication. . 

Want to learn more about wood rot

For those interested in learning more about wood rot, there is a variety of PCA training options for surveying professionals as well as technical/trade professionals. 

Use the search tool below to find available wood rot related training courses or simply go to our training & qualifications section.  Alternatively, if you want to chat to someone, contract our training team on 01480 400 000 or contact them online.

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