Echter Hausschwamm, scientifically known as Serpula lacrymans, is a highly destructive wood-decay fungus. It is commonly referred to as “true dry rot” due to the dry, brittle appearance of the wood it degrades. Despite this common name, the fungus actually requires a specific level of moisture to initiate and sustain its growth, making proper moisture management a primary concern for homeowners.
Understanding Echter Hausschwamm
Serpula lacrymans is a brown rot fungus, meaning it primarily breaks down cellulose and hemicellulose in wood, leaving behind the lignin, which gives the decayed wood its characteristic dark, cuboidal appearance. The fungus prefers a moisture content in wood between 30% and 40% for optimal fruiting body formation, though mycelial growth can occur with a moisture content as low as 20%. It thrives in environments with high relative humidity and poor ventilation, often found in concealed spaces within buildings.
The fungus typically grows best at temperatures around 20-22°C but can survive in a wider range from 3°C to 26°C. Its appearance varies through its life cycle. Initially, it may manifest as a silky, white, cotton-like mycelium, which can develop into thicker, greyish strands known as rhizomorphs. These rhizomorphs allow the fungus to spread over non-nutrient surfaces like masonry and behind plaster to find new timber sources, transporting water and nutrients over distances.
Mature fruiting bodies of Serpula lacrymans are typically plate-like, fleshy, and have an ochre-yellow to rusty-red surface with a white, cottony margin. These fruiting bodies release rusty-red spores, which can spread widely and initiate new infestations.
The Destructive Impact
Echter Hausschwamm causes significant damage to timber and structural elements by degrading the wood’s cellulose and hemicellulose components. This degradation leads to a distinctive cuboidal cracking pattern. This process rapidly diminishes the wood’s strength, making it brittle and unable to support loads, which can severely compromise the structural integrity of a building.
The fungus is particularly aggressive and can spread extensively and quickly compared to other wood-destroying fungi. It causes hidden damage within walls, under floors, and in roof spaces. The extensive nature of the damage can lead to substantial repair costs and a significant reduction in property value.
Preventing Infestation
Preventing an Echter Hausschwamm infestation involves controlling moisture levels within a building. Promptly addressing any leaks from roofs, plumbing, or external sources is important to keep timber dry. Ensure proper drainage around the building’s foundation to prevent water from accumulating and seeping into structural elements.
Improving ventilation in areas prone to dampness, such as basements, crawl spaces, and attics, helps to reduce humidity and prevent moisture buildup. Installing vents or using dehumidifiers in these areas can maintain a drier environment. Using treated timber in construction, especially in areas susceptible to moisture exposure, provides added protection against fungal growth. Regular inspections of a property allow for early detection of moisture problems or signs of fungal growth.
Addressing an Existing Problem
If Echter Hausschwamm is suspected or discovered, professional assessment and remediation are necessary due to its aggressive nature and ability to spread. Specialists can accurately identify the fungus and determine the full extent of the infestation. The remediation process begins with identifying and eliminating the moisture source that allowed the fungus to thrive.
All infected timber and surrounding materials, including plaster and masonry that may contain fungal strands, are removed from the affected area. This removal extends beyond visibly damaged wood to ensure all fungal elements are eradicated. Following removal, fungicidal treatments are applied to the remaining structural elements and surrounding masonry to prevent re-infection. Post-remediation monitoring is then conducted to confirm the effectiveness of the treatment.