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Wet & Dry Rot Treatments

Wet & Dry Rot Treatments

Dry Rot is the most serious form of fungal decay in a building. The decay is caused by a certain species of fungi called Serpula lacrymans, also known as True Dry Rot, that digests parts of the wood which gives the wood strength and stiffness.

Dry Rot is very destructive. It has the ability to pass through inert material to spread to other timbers. The mature fruiting bodies of wood-destroying fungi that develop during an attack produce millions of microscopic spores which are widely dispersed by air currents. Falling on untreated timber they will germinate to form a mass of hyphal threads called mycelium.

Dry Rot affects timbers which are exposed to damp conditions and where there is a general lack of ventilation. Externally exposed timber, timber in contact with wet soil or masonry, or timber subject to a damp atmosphere can all suffer from fungal attack.

Typical indications of dry rot being present include shrinking , darkening and cracks appearing in the timber. Under humid conditions a white fluffy ‘cotton wool’ mycelium develops. Under less humid conditions, a grey/ mushroom coloured skin with patches of yellow often develops. Fruiting bodies are soft, fleshy pancakes with an orange surface. Rust red coloured spore dust are frequently seen around fruiting bodies. The active decay often produces a musty, damp odour.

What is Wet Rot?

The two categories of wet rot - Brown Rots and White Rots - which can both be destructive to timber. Generally brown rots cause cuboidal cracking and shrinking of the timber whilst white rots tend to reduce the timber to a stringy, fibrous texture.

The decay of the timber is typically confined to the area where it has become and remains wet. The high moisture content allows the fungus to establish and develop. Typical causes are gutter leaks, roofing defects, plumbing leaks etc. Damp, Poorly ventilated environments are susceptible to outbreaks of wet rot.

The surveyors at Ambient Preservation will identify the type of fungal infestation and ensure that the correct treatment is specified.

Although wet rot is far easier to control than dry rot, and does not travel through masonry, it is still important to combat it as early as possible. If left untreated it can cause severe damage to your property.

Like dry rot, wet rot is caused by fungi. Unlike dry rot, the fungus which causes wet rot is not aggressive and will die when all moisture is removed from its environment. This fungus needs at least 35% of moisture content and inadequate ventilation to flourish.

However, all wet rot treatments are the same: they depend on the exclusion of moisture and the removal and replacement of infected timbers.

Chemical treatments are not usually required, however, they are provided as a protection to new timbers, or where the fungal growth has been particularly heavy; they can also be used to test the extent of wet rot damage and determine if a rotted but still serviceable timber should remain in place.

The Source:

  • Wet rot is caused by high moisture content and most commonly occurs in very damp areas or areas with poor ventilation.
  • The first signs would usually be rotting of skirting boards and floorboards.

Action to be taken:

  • As with all kinds of rot, the first step of wet rot treatment would be to determine the source of the moisture.
  • Timbers severely infected with fungal growth need to be removed & replaced, while those which are still serviceable may be retained and treated
  • In severe cases of wet rot, chenical damp proofing of affected walls may be necessary