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Wet rot
Wet rot fungus is a type of wood decay that occurs when timber is exposed to excessive moisture, typically above 20-30%. Unlike dry rot, wet rot remains confined to damp areas and does not spread extensively. The most common species responsible is Coniophora puteana, also known as the cellar fungus. It thrives in persistently damp conditions caused by leaks, rising damp, or poor ventilation. Wet rot weakens timber by breaking down its cellulose, causing it to become soft, spongy, and discoloured. Affected wood may crack along the grain and appear darker than surrounding areas. In some cases, a musty smell and fungal growth, such as black or brown spore patches, may be visible. Addressing the underlying moisture problem and replacing damaged wood with treated timber is essential to preventing further decay. And increasing the ventilation where appropriate.
Dry rot is caused by a type of wood-decaying fungus Serpula lacrymans, which thrives in damp, poorly ventilated conditions. It occurs when moisture levels in timber exceed around 20%, often due to leaks, rising damp/penetrating damp or condensation. The fungus breaks down the cellulose and hemicellulose in the wood, weakening its structure and causing it to become brittle and crumbly. Unlike wet rot, which requires continuous moisture, dry rot can spread beyond the initial damp area by producing spores that travel through the air and infect other parts of the building. If left untreated, dry rot can cause severe structural damage, compromising the integrity of floors, walls, and ceilings.
Remedial treatments for dry rot involve eliminating the source of moisture, removing affected materials, and treating the area to prevent recurrence. First, the underlying cause of dampness, such as leaks, poor ventilation, or rising damp/penetrating dampness, must be identified and fixed to stop further fungal growth. Infected timber should be removed and replaced with pre-treated, rot-resistant wood. Surrounding masonry and structural elements should be treated with fungicidal solutions to kill any remaining spores. Improved ventilation and moisture control, such as installing air bricks, dehumidifiers or mechanical ventilation to help prevent future outbreaks. In severe cases, chemical treatments or specialist fungicidal gels may be applied to deeply penetrate and protect the wood and surrounding areas.
